CICR colloquium
SCOSTEP/PRESTOオンラインセミナーシリーズ
SCOSTEPオンライン能力開発講義シリーズ
CICR Colloquium年別リスト
令和5年度（2023年度）
令和4年度（2022年度）
令和2年度（2020年度）
令和元年度（2019年度）
平成30年度（2018年度）
平成29年度（2017年度）
平成28年度（2016年度）
平成27年度（2015年度）
81st ISEE/CICR colloquium
Speaker: Dr. Krucker, S., University of Applied Sciences Northwestern Switzerland, Switerland and UC Berkeley, USA
ISEE coordinator: Dr. Satoshi Masuda (Division for Integrated Studies)
Date and Time: January 22(Wed), 2025, 14:00-15:30
Place: Research Institutes Building I, 3F lecture room (301)
Title: "Catching Solar Flares with ESA's Solar Orbiter mission"
Abstract: The Solar Orbiter mission provides unique observations of our Sun from as close as 0.29 AU with a set of in-situ and remote sensing instruments. As Solar Orbiter is generally far away from Earth, the ability to send data back to Earth is limited. Direct imaging instruments therefore cannot operate continuously making it difficult to catch flares. In this seminar I report on the latest efforts of catching solar flares with Solar Oribter's remote sensing instruments by carefully planning dedicated campaigns ('Solar Flare Watch'). I mainly focus on extreme UV imaging from EUI in combination with hard X-ray observations from the STIX imaging spectrometer. EUI was operating in a 2-s time cadence mode with very short exposure times of 40 ms to avoid saturation during flares. Several GOES M class flares have been observed so far revealing a very close correlation between EUV and HXR emissions in the impulsive phase of the flare linking precipitating flare electrons with individual thermal sources seen in the chromosphere. These observations highlight the small spatial scales of solar flare ribbons in the chromosphere (<150 km), as well as their short live-time (few seconds). I will highlight the importance of these results for modeling the energy transport from the energy release site in the corona (i.e. 'reconnection site') to the chromosphere, and I will discuss implications for future observations in particular for EUVST onboard SOLAR-C.
80th ISEE/CICR colloquium
Speaker: Dr. Lin, H.-H., National Science and Technology Center for Disaster Reduction, Taiwan
ISEE coordinator: Prof. Nobuhiro Takahashi (Center for Orbital and Suborbital Observations)
Date and Time: October 23, 2024 15:00-16:30
Place: Research Institutes Building I, 6F 617
Title: "Application of Big Data and Visualization Technique on Disaster Warning System"
Abstract: In order to enhance disaster early warning technology, the National Science and Technology Center for Disaster Reduction (NCDR) has developed a website called "WATCH" (Weather Analysis and Taiwan Climate Hybrid monitor system) to provide early warning services. For users, easily understandable information translation products will offer more useful disaster assessment information. Additionally, the annual application of meteorological big data will simplify the communication of disaster scenarios through visualization. In July 2023, the European Commission also proposed the Web 4.0 and virtual world initiative, and these related technology blueprints will be gradually implemented. Under this global trend of visualization development, internet services for disaster prevention and rescue technology should consider implementing an information service environment that integrates virtual and real applications. We are also attempting to use virtual reality technology to develop web-based meteorological reality scenarios, providing users with a more realistic visual experience.
79th ISEE/CICR colloquium
Speaker: Dr. Chen, Y.-C., National Science and Technology Center for Disaster Reduction, Taiwan
ISEE coordinator: Prof. Nobuhiro Takahashi (Center for Orbital and Suborbital Observations)
Date and Time: October 22, 2024 13:30-15:00
Place: Research Institutes Building I, 6F 617
Title: "Applications of Meteorological Satellite Data in Disaster Prevention by NCDR"
Abstract: NCDR utilizes the observational data from three satellites in the application of meteorological satellites for disaster prevention: FORMOSAT-7/COSMIC-2 (F7/C2), Japan's HIMAWARI 8/9, and TRITON. F7/C2 is an operational radio occultation (RO) constellation co-developed by Taiwan and the U.S., consisting of six low Earth orbit satellites used to measure the vertical profiles of atmospheric temperature and humidity. NCDR receives this data in real-time and displays the RO-derived temperature and humidity skew-T plots on the WATCH platform. RO observations over the South China Sea are collected daily and converted into moisture indices to monitor moisture transport brought to Taiwan by the southwest monsoon during the Mei-yu period and summer. F7/C2 RO observations are also assimilated to improve the forecast performance of each member in the NCDR ensemble forecasting system.
HIMAWARI's observations are received in real-time from the Central Weather Administration (CWA) as reprocessed data from its 16 channels. These are immediately used to retrieve various cloud properties. An hourly satellite cloud retrieval dataset dating back to 2016 has been established. NCDR has developed integrated satellite cloud map that combines the advantages of IR and VIS cloud map for display purposes using the cloud retrieval data. HIMAWARI observations and their cloud retrievals are also being utilized by NCDR with artificial intelligence techniques to develop surface global horizontal irradiation estimation and quantitative precipitation estimation.
TRITON is a GNSS-R sea surface wind observation satellite independently designed and developed by Taiwan, successfully launched and deployed in October 2023. NCDR has completed the real-time reception of TRITON sea surface wind observation data and is currently developing GNSS-R sea surface wind technology and products for disaster prevention.
78th ISEE/CICR colloquium
Speaker: Dr. Tsai, C.-C., National Science and Technology Center for Disaster Reduction, Taiwan
ISEE coordinator: Prof. Nobuhiro Takahashi (Center for Orbital and Suborbital Observations)
Date and Time: October 21, 2024 10:30-12:00
Place: Research Institutes Building I, 6F 617
Title: "An Update of Radar-related Research Progress in NCDR"
Abstract: This study provides a comprehensive update on radar-related research advancements at NCDR, building on the progress presented by the authors at ISEE in 2023. The updated progress is structured around five key topics: (1) 3D wind retrieval: initial results have been achieved by integrating MP-PAWR data with the WISSDOM technology; (2) dual-polarization radar QPE: a comprehensive validation of QPE data for the year 2023 has been conducted across various regions of Taiwan, with a particular focus on assessing the performance of QPE during heavy rainfall events; (3) rainfall kinetic energy: the study introduces an algorithm for estimating rainfall kinetic energy using dual-polarization radar, along with associated monitoring products and results from monitoring landslide-prone areas during typhoon events; (4) severe weather monitoring: this section covers radar vertical profile monitoring products and research on early warning signals based on dual-polarization variables, aimed at enhancing severe weather prediction; (5) ExAMP blending scheme: through statistical evaluations across different months in Taiwan, the study demonstrates the differences in very short-term QPF capabilities between ExAMP and standalone WRF models. This update highlights significant progress in radar technology applications for disaster monitoring and prediction, emphasizing the potential for improved early warning systems and disaster risk reduction.
77th ISEE/CICR colloquium
Speaker: Professor P. N. Vinayachandran, Chair, Centre for Atmospheric and Oceanic Sciences, India
ISEE coordinator: Dr. Aiki (Division for Land-Ocean Ecosystem Research)
Date and Time: Thursday, October 17, 2024 15:00-16:00
Place: Research Institutes Building I-717
Title: "Features of the Southern Bay of Bengal from Bay of Bengal Boundary Layer Experiment (BoBBLE)"
Abstract: The southern Bay of Bengal (BoB) is characterized by intriguing features of the ocean-atmosphere system. A field experiment in the southern Bob was conducted to generate high-quality in situ observational datasets of the ocean, air–sea interface, and atmosphere during the summer monsoon of 2016. Ship-board observations were carried out along the 8°N section (between 85.3 and 89°E) and a 10-day time-series at 89°E, 8°N (TSE). The ocean instrumentation included CTD, gliders, VMP, uCTD, ADCP, radiometer, TSG, Argo floats, drifting buoys, and water sampling to measure physical, chemical, and optical parameters. Two AWS, an eddy covariance system, and radiosonde were deployed for measurements of the atmosphere. These measurements provided a comprehensive view of the ocean atmosphere system. In addition, an operation-advection was carried out in order to determine the local and advective terms of the mixed layer temperature evolution using in situ observations alone. The western part of the southern BoB is marked by the intense Summer Monsoon Current (SMC) that flows into the BoB with a cyclonic circulation known as Sri Lanka Dome (SLD) on its western flank. BoBBLE observations characterized both features and assessed the processes controlling SMC variability. These observations captured events of barrier layer (BL) erosion and reformation showing the differential roles of low salinity BoB water and advection by SMC on the mixed layer depth. High salinity water from the Arabian Sea flows into the BoB as a High Salinity Core (HSC) below the upper mixed layer. HSC was composed of relatively warmer and saline Arabian Sea water overlying the cooler and fresh BoB water creating conditions favourable for double-diffusive salt fingering instability. In addition, the HSC is rich in oxygen which is transferred to the BoB waters. Model simulations and Argo profiles show that the HSC spreads into the northern BoB, oxygenating the water en route, and thus offers a new mechanism that prevents the OMZ from tipping to a denitrification regime. A novel techniques was developed for observational experiments to quantify the mixed layer heat budget. Processes controlling mixed layer budget at TSE was determined. Using fluorescence measurements from gliders and CTD, the association between deep chlorophyll maximum and physical processes were also determined. In summary, using multiple in situ platforms, the spatial and temporal evolution of features of the southern BoB were delineated using BoBBLE datasets and underlying processes explored. Future goals include incorporating the observational knowledge gained by the field program into physical process models and to determine the sensitivity of the monsoon system to ocean–atmosphere interactions in the southern BoB.
76th ISEE/CICR colloquium
Speaker: Professor Balan Nanan, Designated Professor of ISEE, Shandong University, China
ISEE coordinator: Dr. Otsuka (Division fo:r Ionospheric and Magnetospheric Research)
Date and Time: July 11, 2024 17:15-18:15
Place: Research Institutes Building II（研究所共同館Ⅱ）, 3F Hall
Title: "Fresh Look at the Intensity and Impulsive Strength of Geomagnetic Storms Having Positive MPO"
Abstract: The geomagnetic storms (unexpected temporal changes in the geomagnetic field) have been studied for over 150 years using data and indices like Dst and SymH. The storms, in general, consist of the initial phase (IP), main phase (MP) and recovery phase (RP). Recently, we notice that the important early decreasing part of the main phase (MP) from the positive main phase onset (MPO) to 0-level of Dst and SymH indices is missed in the treatment of the main phase (MP) in the literature.
We correct and explain this inconsistency in the 1115 storms having positive MPO (out of 1350 storms) in SymH during 1981–2023 by raising the 0-level of SymH to the MPO-level. The correction considers the full range of the main phase, increases the corrected storm intensity (SymHMin*) and impulsive strength (IpsSymH*) by up to −149 nT and −134 nT, respectively, compared to their uncorrected values.
The correction seems important for all aspects of global space weather. For example, the corrected SymHMin* largely changes the conventional storm identification and classification and corrected IpsSymH* clearly identifies all 3 severe space weather (SvSW) events from over 1300 normal space weather (NSW) events with a large separation of 52 nT; it also identifies all 8 minor-system-damage space weather (MSW) events from the NSW events.
The correction is physical meaningful. The decrease of SymH from MPO to (original) 0-level is found mainly due IMF Bz turning southward (or increase in westward ring current) in majority of the cases. Only in a small number of cases, the decrease is mainly due to the sudden decrease in the solar wind dynamic pressure (or decrease in eastward magnetopause current).
75th ISEE/CICR colloquium (face-to-face meeting)
Speaker: Dr. Martha Arbayani Zaidan, Department of Computer Science and Institute for Atmospheric and Earth System Research / Physics, University of Helsinki, Finland
ISEE coordinator: Prof. Michihiro Mochida
Date and Time: June 10 (Mon), 2024, 13:30-15:00
Place: Research Institutes Building II（研究所共同館Ⅱ）, 3F Hall
Title: "AI Technologies for Enhancing Sensor Networks: Accuracy, Reliability, and Autonomy"
Abstract: The deployment of sensor networks has been crucial in providing continuous monitoring of our environment. These networks come in various forms, including permanent research stations, official environmental monitoring stations, and low-cost sensor-based networks. While permanent research stations serve as comprehensive infrastructures for scientific purposes, environmental monitoring stations provide real-time information to decision-makers and relevant stakeholders. Low-cost sensor networks, being easy to deploy and affordable, can be massively deployed to offer better spatial coverage with higher temporal resolution. The widespread use of massive sensor networks brings challenges in generating high-quality data, ensuring reliability, and enabling automatic data processing and analytics. This talk will address these challenges by promoting the use of AI technologies. As a case study, we will demonstrate the automation of new-particle formation (NPF) identification and analysis. NPF events, derived from particle-size distributions measured by aerosol instruments at research stations, have traditionally been identified semi-automatically. Recently, computer vision methods have been employed to detect these events automatically. However, current methods face issues with accuracy and computational time efficiency. We propose a physics-guided machine-learning method to address these challenges. The method combines aerosol physics and machine learning methods to merge both strengths enabling generalization and better performance. Our results show that this method improves accuracy and enhances computational time efficiency. Finally, the talk will also explore the broader role of AI in enhancing the autonomy of sensor networks.
74th ISEE/CICR colloquium (face-to-face meeting)
Speaker: Prof. Irina Panyushkina,Laboratory of Tree-Ring Research, University of Arizona, USA
ISEE coordinator: Prof. Tetsuya Hiyama and Prof. Fusa Miyake
Date and Time: February 6 (Tue), 2024, 13:00-15:00
Place: Research Institute Building I (研究所共同館Ⅰ), 6F Meeting Room (No.617)
Title: "Tracking the impact of Arctic amplification on terrestrial hydrology with tree rings"
Abstract: Arctic climate is uniquely sensitive to changes in climate forcing. Arctic Amplification unfolding over the last 25 years raises many questions about the feedback of terrestrial systems coupled with the Arctic system. My research emphases modeling of pre-instrumental streamflow with tree-ring proxies to understand the response of seasonal hydrology to Arctic Amplification. I will present a tree-ring reconstruction of the Yenisei River discharge for the last 250 years and discuss the impacts of fast-track permafrost thawing and intensified regime of boreal forest fires on the irregularity and unprecedented changes of hydrology across the Yenisei River basin. Additionally, I will touch base on a new web-based tool TRISH, Tree-Ring Integrated System for Hydrology. The tool helps to explore the hydrologic signal in a network of tree-ring chronologies using map server, water balance modeling outputs and R-based software for calibrating complex regression models. The tool is an open-science resource designated for using broadly in Environmental Sciences and for solving practical problems of ecological, economic, or social systems in the Arctic.
73th ISEE/CICR colloquium (hybrid)
Speaker: Prof. Khan-Hyuk Kim, Department of Astronomy & Space Science, Kyung Hee University, South Korea
ISEE coordinator: Prof. Kazuo Shiokawa
Date and Time: November 30 (Thu), 2023, 16:30-18:00
Place: Research Institute Building II (研究所共同館Ⅱ) 3F Hall or Zoom
Title: "Transversely heated low-energy helium ions by EMIC waves in the plasmasphere"
Abstract: The Radiation Belt Storm Probes-A (RBSP-A) spacecraft observed strong ~0.5-Hz helium
(He+) band and weak ~0.8-Hz hydrogen (H+) band EMIC waves on 17 April 2018, at L =
~4.5-5.2, in the dawn sector, near the magnetic equator, and close to the outer edge of
the plasmasphere. We examined low-energy ion fluxes observed by the Helium Oxygen
Proton and Electron (HOPE) instrument onboard RBSP-A during the wave interval and
found that low-energy He+ flux (< 10 eV) enhancements occur nearly simultaneous
with He-band and H-band EMIC wave power enhancements in a direction mostly
perpendicular to the background magnetic field without significant low-energy H+ and
O+ flux variations. We suggest that cold He+ ions (<1 eV) are preferentially and
transversely heated up to 10 eV through the interaction with EMIC waves inside the
plasmasphere. The low-Earth orbit spacecraft observed an isolated spectral enhancement,
which is short-lived and lasting only ~1 min, at ~0.5 Hz and localized precipitations of
energetic protons in the upper ionosphere at subauroral latitudes near the magnetic
field footprint of RBSP-A. Our observations provide clear evidence that EMIC waves play
an important role in the overall dynamics in the inner magnetosphere, contributing to
the loss and energization of magnetospheric particles.
72th ISEE/CICR colloquium (hybrid)
Speaker: Dr. Jyrki Manninen, Sodankyla Geophysical Observatory, University of Oulu, Finland
ISEE coordinator: Assoc. Prof. Claudia Martinez-Calderon
Date and Time: October 26 (Thu), 2023, 16:30-18:00
Place: Research Institute Building II (研究所共同館Ⅱ) 3F Hall or Zoom
Title: "What has happened in the 'VLF field' since summer 2022 in Finland?"
Abstract:
Background
Very low frequency (VLF) waves have been recorded temporarily in Finland since 1970’s. Sometimes there have been gaps of even several years between observations. All recordings were a kind of hobby for Prof. Tauno Turunen who was interested in all different kinds of geophysical phenomena and instrumentation. Finally, in the early 1990’s he made a VLF receiver for signals transmitted from the Russian Activnyij (Intercosmos-24) satellite. Unfortunately, there were no artificial signals received at all, and thus the receiver was used for detecting natural VLF waves. At that time, Jyrki Manninen joined Tauno’s team as a master student. This receiver yielded one master thesis. In 1992, Tauno built a new VLF receiver nick-named VLF100aT. It was the most sensitive VLF receiver in the world, and it is still now, 31 years later. It took more than 10 years to get a digital data recording system for it. Since 2006, this receiver has been at Kannuslehto in Northern Finland (KAN, MLAT=64.9°N, L=5.5). Originally, we had 1 to 3-week campaigns every year.
Just in 2016, when Dr. Shin-Ichiro Oyama installed one Japanese high-speed auroral camera in Sodankylä, and we started to have longer campaigns. Also, the launch of the ERG/Arase satellite in December 2016 motivated us to get more VLF data. Since autumn 2016, we have had winter campaigns from early September to late April to cover observations of optical aurora.
Recent developments
Finally, on 7 September 2021 we started our current campaign which has been running continuously except for some short breaks due to malfunctions with electricity. Only 3 full days have been lost so far. Already before COVID-19, we started some discussions with ISEE about the possibility of installing one PWING receiver in Finland. The instrumentation arrived at Sodankylä Geophysical Observatory in spring 2021. Due to the corona pandemic, we were able to select the place for the receiver just in August 2022. The best place we found was Oulujärvi (OUJ, MLAT=61.6°N, L=4.4). That place already had a magnetometer and proper connections. Installation was made on 10 September 2022 and since then, it has produced VLF data for the PWING network.
Here we present details on the instrument installation and location parameters, as well as some observations from OUJ since October 2022. Observations are also compared to simultaneous KAN observations. A few steps towards wider use of dedicated sferics and PLHR filters will be discussed. Maybe also some ideas to enlarge PWING chain in Finland will be revealed.
71th ISEE/CICR colloquium (hybrid)
Speaker: Dr. Vyacheslav (Slava) Pilipenko, Designated Professor of ISEE / Head of Laboratory, Institute of Physics of the Earth, Moscow, Russia
ISEE coordinator: Prof. Kazuo Shiokawa (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: May 18 (Thu), 2023, 16:30-18:00
Place: Research Research Institutes Building II, 3F Hall
Title: "Electromagnetic Pollution of the Near-Earth Space by ULF-ELF Ground-Based Transmitters"
Abstract: The leakage of the electromagnetic waves into the outer space (“pollution”) from ground
radio-transmitters and lightning discharges is well examined effect in the VLF (several kHz)
range. The feasibility of electromagnetic response in the upper ionosphere to ground
large-scale ULF-ELF transmitters (1-100 Hz) has not been studied yet. Examples of such
mega-transmitters are aerials for submarine communication, installations for global
magnetotelluric sounding with artificial ULF-ELF signals, and unbalanced industrial
50/60 Hz power transmission lines. We model the rate of the ULF-ELF wave energy
leakage into the upper ionosphere from an oscillating grounded linear current with
a finite length suspended above a high-resistive ground. A realistic altitudinal profile
of the plasma parameters has been reconstructed with the use of the IRI ionospheric
model. Numerical modeling predicts that emission from these systems under realistic
driving current intensities can be detected by low-orbiting satellites in the topside
ionosphere. Moreover, the stimulation of artificial Pc1 pulsations (0.5 Hz) by large-scale
decommissioned power lines is possible with driving current >100 A. Analysis of satellite
observations shows that nowadays our planet happens to be in the frequency band
50-150 Hz in an electromagnetic environment produced rather by industrial activity
than by natural magnetospheric processes.
70th ISEE/CICR colloquium (hybrid)
Speaker: Prof. Pekka T. Verronen, Designated Professor of ISEE visiting professor / Finnish Meteorological Institute, Finland
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science)
Date and Time: Apr 13 (Thu), 2023, 13:30-15:00
Place: Research Research Institutes Building II, 3F Hall
Zoom meeting : Please contact miyoshi_@_isee.nagoya-u.ac.jp for Zoom meeting URL
Title: "Ozone impact from solar energetic particles cools the polar stratosphere"
Abstract: Understanding atmospheric impacts of solar energetic
particle precipitation (EPP) remains challenging, from quantification
of the response in ozone, to implications on temperature. Both are
necessary to understand links between EPP and regional climate
variability. Here we use a chemistry-climate model to assess the
importance of EPP on late winter/spring polar stratosphere. In
transient simulations, the impact on NOy, ozone, and temperature is
underestimated when using EPP forcing from the current recommendation
of the Coupled Model Intercomparison Project (CMIP6). The resulting
temperature response is largely masked by overall dynamical
variability. An idealised experiment with EPP forcing that reproduces
observed levels of NOy results in a significant reduction of ozone (up
to 25%), cooling the stratosphere (up to 3 K) during late winter/
spring. Our results unravel the inconsistency regarding the
temperature response to EPP-driven springtime ozone decrease, and
highlight the need for an improved EPP forcing in climate simulations.
69th ISEE/CICR colloquium (hybrid)
Speaker: Prof. Gary P Zank, Center for Space Plasma and Aeronomic Research and Department of Space Science, University of Alabama in Huntsville, USA
ISEE coordinator: Dr. Kazumasa Iwai (Division for Heliospheric Research)
Date and Time: Mar 30 (Thu), 2023, 13:30-15:00
Place: Research Institutes Building II, 3F Hall
Zoom meeting : Please contact k.iwai_@_isee.nagoya-u.ac.jp for Zoom meeting URL
Title: "Heating the Solar Corona and Driving the Solar Wind: Are we nearing a solution?"
Abstract: A primary goal of the NASA Parker Solar Probe Mission and ESA Solar Orbiter Mission is to determine the heating mechanism that accounts for the very high temperature of the plasma in the solar corona. After several years of measurements, we are beginning to gain a far better idea about how the heating process may operate. A survey of the relevant observations will be presented followed by a discussion of how these may relate to theoretical models. Specifically, various heating mechanisms have been suggested but one that is gaining increasing credence is associated with the dissipation of low frequency magnetohyrodynamic (MHD) turbulence. However, the MHD turbulence models come in several flavors. Two basic MHD turbulence transport models have been developed, one in which outwardly propagating Alfven waves experience reflection from the large-scale flow and density gradients associated with the solar corona, and the resulting counterpropagating Alfven waves couple nonlinearly to produce quasi-2D turbulence that dissipates and heats the corona. The second approach eschews a dominant outward flux of Alfven waves but argues instead that quasi-2D turbulence dominates the lower coronal plasma, is generated in the constantly upwelling magnetic carpet, experiencing dissipation as it is advected through the corona, leading to temperatures in the corona that exceed a million degrees. We will review the two theoretical turbulence models, describe the basic modeling that has been done, and compare with Parker Solar Probe and Solar Orbiter observations.
68th ISEE/CICR colloquium (hybrid)
Speaker: Dr. Matthias Förster, GFZ German Research Centre for Geosciences, Germany
ISEE coordinator: Dr. Nozomu Nishitani (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: Feb 27 (Mon), 2023, 13:15-14:15
Place: Research Institutes Building I, 7th floor Meeting Space Room (717)
Zoom meeting : Please contact nisitani_@_isee.nagoya-u.ac.jp for Zoom meeting URL
Title: "Estimation of effective ion masses by Langmuir probes onboard the Swarm satellites"
Abstract: The present default Langmuir Probe (LP) algorithm for estimating the plasma density
relies on three major suppositions: the orbital motion limited (OML) theory is
applicable, the surrounding plasma consists of pure oxygen ions only, and the
along-track ion velocity coincides with the spacecraft orbital speed. These
assumptions are routinely violated, particularly with respect to ion composition
on the nightside and during periods of low solar activity as well as at auroral
and polar latitudes, where ion drifts of magnetospheric origin are dominating.
Both factors are compromising the accuracy of the plasma density measurements.
Further, numerical simulations of the spacecraft's plasma environment and
observational results have shown that plasma shielding effects are not negligible.
Their effect has been taken into account by empirically estimated corrections of
the effective faceplate area and the actual cross section of the LP.
The recently developed novel SLIDEM (Swarm LP Ion Drift and Effective Mass) product
allows to relax some of these assumptions and yields further estimates about the
along-track ion drift and effective ion mass. This is done by additional use of
the ion current to the faceplate at Swarm's front side, where the Thermal Ion
Imager (TII) of the electric field instrument is mounted, together with the
corrected ion admittance of the LP. This approach, in the form of the SLIDEM data
product, allows for more accurate density estimations, together with simultaneously
estimated additional plasma parameters - the effective (or reduced) ion mass and
the along-track ion drift component. Thus it provides new possibilities for upper
ionosphere studies and the space weather responses to external drivers.
67th ISEE/CICR colloquium (hybrid)
Speaker: Prof. Emer. Hermann Opgenoorth, Designated Professor of University of Umea, Sweden
ISEE coordinator: Dr. Nozomu Nishitani (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: Feb 20 (Mon), 2023, 13:30-15:00
Place: Research Institutes Building I, 3rd floor Lecture Room (301)
Zoom meeting : Please contact nisitani_@_isee.nagoya-u.ac.jp for Zoom meeting URL
Title: "On the Origins and characteristics of Three-Dimensional Current Systems in Near-Earth
Space and their Implications for Space Weather"
Abstract: Early studies of “geo-magnetism” dealt with the understanding of
long-term developments and short-term disturbances in the geo-
magnetic field as measured by magnetometers on ground level.
Soon after the IGY the concept of several co-existing and globally
or locally interacting ionospheric current systems (DP1 & 2) was
born. Both systems seemed to respond differently to solar wind
driving conditions and internal magnetospheric processes. Through
continued global international study efforts, like e.g. the International
Magnetospheric Study (IMS) and later the International Solar Terrestrial
Physics program (ISTP) the 2-dimenional geomagnetic “disturbances”,
are now understood as complex signatures of completely different
three-dimensional current systems within and beyond the upper
atmosphere. Ground-based magnetometer networks together with
magnetometers in orbit became a powerful tool to monitor and study
the complicated three-dimensional coupling of the magnetosphere to
the upper atmosphere and its ultimate relation to certain solar wind
drivers of magnetospheric conditions.
The ultimate goal of such measurements today is not only to identify
the energy and activity state of the magnetosphere as such, but also
to study the exact location, strength and spatio-temporal development
of the most powerful short-lived magnetic disturbances that we know,
the so-called magnetospheric substorms and the closely related
intensifications of major magnetic storms.
The fast-growing research and operational field of Space Weather has
stimulated new active research (including advanced model efforts) to
get to the bottom of some of the most effective geo-space plasma
phenomena, and to understand the variability of ionospheric currents,
and their connection to the outer magnetosphere. This is at present one
of the most intriguing scientific problems in the field of Space Weather.
Potentially any conducting infrastructure on the ground can be
detrimentally or catastrophically affected by fast changes in the
magnetic field (dB/dt) via geomagnetically induced currents (GICs).
In parallel, the involved ionospheric current systems can cause further
secondary impacts on space-borne communication and navigations
systems via ionospheric plasma instabilities and atmospheric drag
effects on satellite orbits.
In my presentation I will give a short background to the progress of
space science with the help of magnetometer data, and then highlight
a selection of recent research topics, where global and regional
magnetometer networks (together with a multitude of dedicated space
missions) represent a very important part of the systematic and
coordinated study of the near-Earth plasma environment, the coupled
solar wind - magnetosphere - ionosphere – atmosphere “System
of Systems”.
66th ISEE/CICR colloquium (hybrid)
Speaker: Dr. Pavlo Ponomarenko, Designated Professor of ISEE visiting professor / University of Saskatchewan, Canada
ISEE coordinator: Dr. Nozomu Nishitani (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: Feb 9 (Thu), 2023, 17:15-18:00
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Zoom meeting : Please contact nisitani_@_isee.nagoya-u.ac.jp for Zoom meeting URL
Title: "Towards empirical model of HF propagation at very high latitudes"
Abstract: Conventional forecasting of high-frequency (HF, 3-30 MHz) radio wave
propagation is based on a combination of model ionosphere and model
propagation mechanism, and it proved to be reliable at mid and low
latitudes. However, at very high latitudes this approach becomes
considerably less reliable due to the intrinsically dynamic ionospheric
conditions regularly perturbed by energetic particle precipitations and
strong electric fields. To improve the situation, multi-year data from
SuperDARN radars across high-latitude regions are currently being
used for creating an empirical propagation model directly from the
radar observations. Qualitative identification and quantitative
characterisation of the HF propagation modes is performed based on
an accurate knowledge of the vertical angle of arrival (elevation angle)
of the radar echoes. This information has become available only
recently, facilitated by the development of observation-based
calibration techniques for SuperDARN interferometry. In this talk the
current progress of the empirical model development will be reported,
including a solar-cycle long climatology of HF propagation
characteristics at very high latitudes based on data from the Rankin
Inlet SuperDARN radar.
65th ISEE/CICR colloquium (online)
Speaker: Prof. Rumi Nakamura, Designated Professor of ISEE, Nagoya University / Austrian Academy of Sciences - Space Research Institute, Austria
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science)
Date and Time: Dec 20 (Tue), 2022, 10:00-11:30
Place: Zoom meeting (Please contact miyoshi_@_isee.nagoya-u.ac.jp for Zoom meeting URL)
Title: "In-situ observation of magnetic reconnection:
diffusion region and outflow disturbances"
Abstract: Magnetic reconnection is a fundamental energy conversion process in
space plasma. In the near Earth’s space, magnetic reconnection results
in transport of energy and momentum and mass from the solar wind to
the magnetosphere and drives sporadic and large-scale energy transfer
processes such as substorms and storms. The overall Earthward
magnetic flux transport in the magnetotail is considered to be driven
by two types of magnetic reconnection that takes place in the
magnetotail current sheet: quasi steady reconnection in the distant
tail causing slow background flow and transient magnetic reconnection
near Earth (Earthward of 30 RE) creating high-speed plasma jets that
are frequently associated with substorms. In addition to these
conventional reconnection in the magnetotail current sheet,
reconnection signatures have been reported also in the flow braking
region where thin vertical current sheet can be created as a
consequence of interaction between the fast plasma flows and the
Earth’s dipole field.
Multi-point spacecraft measurements from Cluster and THEMIS enabled
to study magnetic reconnection in terms of large-scale consequence and
ion-scale physics in detail by obtaining the spatial structure using
multi-spacecraft capabilities. The four-point high-time resolution
measurements from Magnetospheric Multicale (MMS) mission enable us for
the first time to resolve the electron dynamics as well as the
geometry of the thin electron-scale current sheet. In particular,
these multi-point measurements allow to monitor also the motion of the
structures such as X-line, current sheets, and separatrix, which are
important for determining the different parameters for reconnection.
In this talk we highlight selected reconnection events in the
near-Earth magnetotail for which the reconnection electric fields are
obtained based on different multi-point analysis methods applied to
in-situ observations of the diffusion region as well as the
observations of remote reconnection site at separatrix region as well
as the outflow regions to discuss the large-scale consequence of the
magnetic reconnection in geospace.
64th ISEE/CICR colloquium (online)
Speaker: Prof. Rangaiah Kariyappa, Designated Professor of ISEE, Nagoya University / Indian Institute of Astrophysics, India
ISEE coordinator: Prof. Kanya Kusano (Division for Integrated Studies)
Date and Time: Jul 7 (Thu), 2022, 09:00-10:30
Place: Zoom meeting (Please contact y-bamba_@_nagoya-u.jp for Zoom meeting URL)
Title: "Solar Spectral Irradiance (SSI) Variability"
Abstract: The Sun is the primary source of energy responsible for governing
both the weather and climate of Earth. The variations in the EUV
& UV and X-ray irradiance are produced by surface manifestation of
solar magnetic activity. Considering the variations in the solar EUV
& UV and X-ray fluxes may cause significant changes in the Earth’s
climate, understanding the physical origin of EUV, UV & X-ray
irradiance changes is an extremely important issue in Solar and Space
Physics. The study of solar irradiance variability measured in
different wavelengths is of great interest and importance in
heliophysics, Earth’s climate, and space weather applications.
In this talk, the important problems in solar irradiance variability
will be addressed. The importance of the spatially resolved and
segmented both intensity and magnetic field images of the Sun
observed in several wavelength bands and how they have been used
to clarify & to understand, particularly, the EUV & UV and X-ray
irradiance variabilities - which are measured the Sun as a Star-
will be discussed. The different contributors to such irradiance
variations are discussed. Further, the role of underlying
photospheric magnetic field in spatial correspondence (or relation)
with the various magnetic emission features in the modulation of
the solar spectral irradiance variations will also be presented.
63rd ISEE/CICR colloquium (online)
Speaker: Prof. Jyrki Manninen, Designated Professor of ISEE, Nagoya University / Sodankyla Geophysical Observatory, University of Oulu, Finland
ISEE coordinator: Dr. Claudia Martinez-Calderon (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: May 12 (Thu), 2022, 16:30-18:00
Place: Zoom meeting (Please contact claudia_@_isee.nagoya-u.ac.jp for Zoom meeting URL)
Title: "VLF bursty-patches – new phenomena?"
Abstract: VLF bursty-patches are a relatively recent type of differently structured very low frequency (VLF) radio waves. Their main characteristic being that they are detected at frequencies above the half and full electron gyrofrequency (fce) in the equatorial plane for the L-shell of observation site. They have been observed sporadically since 1970’s, but the number of observations increased explosively since digital sferics filter was developed at Sodankyla Geophysical Observatory. In this study we used data from the VLF receiver of Kannuslehto, Finland (KAN, MLAT=64.4°N, L=5.5) with an average fce of 6 kHz, where VLF bursty-patches are commonly detected.
Here we present a review of the results of the analysis of these newly discovered VLF bursty-patches at KAN during winters 2006-2022. These emissions have rarely been observed in traditional spectrograms because they are usually hidden by strong impulsive atmospherics (sferics, originating in lightning discharges) in the same frequency range. VLF bursty-patches typically occur as sequences of short right-hand polarized burst-like patches with a separation of ~1-3 min and lasting several hours.
The occurrence of VLF bursty-patches seems to be strongly related to solar activity. Annual occurrence rate varies between 9.5% and 72.5% of observation days. The lowest rate was in 2018 and the highest rate in 2014 (and in 2016).
62nd ISEE/CICR colloquium (online)
Speaker: Prof. C. Z. (Frank) Cheng, Designated Professor of ISEE, Nagoya University / Princeton Plasma Physics Laboratory, Princeton University, USA
ISEE coordinator: Prof. Kanya Kusano (Division for Integrated Studies)
Date and Time: Feb 3 (Wed), 2021, 13:30-15:00
Place: Zoom meeting (Please contact kusano_@_isee.nagoya-u.ac.jp for Zoom meeting URL)
Title: "Physics of Magnetic Reconnection"
Abstract: Magnetic reconnection (MR) plays a crucial role in converting electric and magnetic energy into plasma energy. The theoretical MR physics research has evolved from MHD theory to two-fluid theory to full kinetic plasma theory and simulations. Many new kinetic reconnection phenomena were discovered. For example, the quadrupolar out-of-plane magnetic field is produced due to much faster electron outflow velocity than ion outflow velocity. The parallel electric field is produced around the separatrix regions and accelerates electrons to flow toward the current sheet direction. The decoupling of electron and ion dynamics due to their different orbit meandering widths across the current sheet causes charge separation and produces large electrostatic potential well and bipolar electric field. The magnetic energy is mostly converted to ions. I will first introduce Particle-In-Cell (PIC) simulation results of driven magnetic reconnection. Then, I will introduce an analytic theory of the reconnection current sheet profile structure of electron and ion densities, and electric and magnetic fields during steady state magnetic reconnection. The analytic formula depends on the upstream plasma and magnetic field parameters and the driving electric field. The theory predicts that both the bulk ion and electron temperature gains are proportional to the square of the reconnecting magnetic field, which is consistent with laboratory experimental results and space observations. The analytic formula allows scaling for different upstream conditions of plasma, magnetic field and driving electric field.
61st ISEE/CICR colloquium
Speaker: Dr. Matthias Förster, GFZ German Research Centre for Geosciences, Germany / Max-Planck-Institute for Solar System Research (MPS), Germany
ISEE coordinator: Dr. Nozomu Nishitani (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: Feb 20 (Thu), 2020, 14:30-16:00
Place: Research Institutes Building I (ISEE), 8th floor meeting space (817)
Title: "Symmetries and asymmetries of the Earth's magnetic field and their implications
for the magnetosphere-ionosphere-thermosphere (M-I-T) coupling"
Abstract: Disturbances in the solar wind and interplanetary magnetic field (IMF) affect
the Earth’s high-latitude thermosphere and ionosphere via coupling with the
magnetosphere. Recent observations have shown that the upper thermospheric and
ionospheric response to solar wind/IMF dependent drivers of the M-I-T system
can be very dissimilar in the Northern (NH) and Southern Hemisphere (SH).
Event studies of geomagnetic storms indicate that strong hemispheric asymmetries
can surprisingly occur in the thermosphere and ionosphere, even if the storm
happens to occur close to equinoctial seasonal conditions. Some storms show
striking hemispheric asymmetries in its positive and negative phases, caused
by very particular combinations of their driving mechanisms, and accompanied by
significant longitudinal variations and strong thermospheric composition changes.
Statistical studies of both ground- and satellite-based observations show
hemispheric differences in the average high-latitude electric field patterns,
associated with magnetospheric convection, as well as hemispheric differences
in ion drift and neutral wind circulation patterns. The cross-polar neutral
wind and ion drift velocities are generally larger in the NH than the SH, and
the hemispheric compilation shows a semi-diurnal variation. The vorticity of
the upper thermospheric horizontal wind is also larger in the NH than in the SH,
with larger differences for higher solar activity. In contrast, the spatial
variance of the neutral wind is considerably larger in the SH polar region.
These hemispheric differences can be explained at least to some extent by
asymmetries in the Earth’s magnetic field, both in magnetic flux density and
in the offset between the geographic and invariant magnetic poles.
60th ISEE/CICR colloquium
Speaker: Prof. Dr. Iskhaq Iskandar, University of Sriwijaya, Indonesia
ISEE coordinator: Prof. Joji Ishizaka (Division for Land–Ocean Ecosystem Research)
Date and Time: Feb 6 (Thu), 2020, 15:00-15:45
Place: Research Institutes Building I (ISEE), 8th floor meeting space (817)
Title: Recent Progress on the Study of Satellite-Observed Surface Chlorophyll-a Variability within the Indonesian Waters and Its Relation to Physical Environmental Changes
Abstract: With the availability of the increased amount of remotely sensed data, here we show a recent progress on the study of surface chlorophyll-a (Chl-a) variability within the Indonesian waters to understand the impact of physical environmental changes on low-trophic level marine ecosystems. We focused on two regions of interest, namely the Southeastern Tropical Indian Ocean (SETIO) off Sumatera-Java in the western part of Indonesia, and the Halmahera Sea in the eastern part of Indonesia. The SETIO region experiences significant seasonal and interannual variations in wind forcing. The seasonal reversal of the monsoon winds is shown to generate strong seasonal upwelling along the southern coast of the Lesser Sunda Islands (e.g. Sumatra, Java and Nusa Tenggara Island chain). Moreover, interannual variations associated with the Indian Ocean Dipole (IOD) are shown to cause anomalously strong upwelling off of Sumatra-Java. An empirical orthogonal function (EOF) analysis was applied on the seasonal time series of the satellite observed surface Chl-a concentration, sea surface temperature (SST) and surface winds. Spatial eigenfunctions of the first EOF mode reveal broad areas that exhibit coherent temporal variation in Chl-a, SST and Ekman pumping in the SETIO region. The corresponding principal component time series reveals a robust seasonal variation and relatively weak interannual variation. The second EOF mode exhibited strong interannual variation in Chl-a, appearing mostly off Sumatra-Java, and co-located with 180° out of phase variation in SST and in phase variations in both Ekman pumping and wind-induced mixing. Similarly, the Halmahera Sea region also experiences strong seasonal variation associated with the monsoonal winds. The strengthening of southeasterly wind stress (up to ~0.01 N m-2) during the Southeast Monsoon season (June – August) produces enhanced Chl-a concentrations (up to ~0.59 mg m-3) associated with ocean surface cooling (~28.8°C) in the area of study. On the other hand, the Chl-a bloom completely diminishes during the Northwest Monsoon season (December – February). On an interannual time scale, sea level pressure and wind stress are coherent with ENSO and IOD phases. During El Niño and positive IOD events (La Niña and negative IOD events), both sea level pressure and wind stress greatly increases (decreases) over the Halmahera Sea. These conditions cause an anomaly in southerly (northerly) wind stress, which is favorable to an enhancement (reduction) of the Chl-a concentration in the region. This study demonstrates that sea level pressure and wind stress are the critical factors in determining the magnitude of Chl-a bloom in the Halmahera Sea.
59th ISEE/CICR colloquium
Speaker: Prof. D. Knipp, University of Colorado, Boulder, USA
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science)
Date and Time: Jan 31 (Fri), 2020, 10:30-12:00
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Title: Reconstructing Large Scale Field Aligned Currents from Short Segments
of AMPERE Data
Abstract: The primary modes of Field-aligned current (FAC) variability and their
hemispheric asymmetry are determined from a linear regression analysis
of a multi-year, global data set of Iridium constellation
engineering-grade magnetometer data from the Active Magnetosphere and
Planetary ElectrodynamicsResponse Experiment (AMPERE) program. The
first two modes of variability as determined by Empirical Orthogonal
Function (EOF) analysis are associated with solar-wind coupling; the
third EOF is associated with the ecliptic components of the
interplanetary magnetic field. I will present examples of quiet and
disturbed high-latitude FACs and toroidal magnetic potential patterns
in both hemispheres reconstructed at a 2-min cadence AMPERE data using
an updated optimal interpolation (OI) method. The OI application
shows strong hemispheric asymmetries under various driving conditions.
I will also discuss the use of the OI application to investigate and
distinguish various elements of interplanetary shock response in the
field aligned currents.
58th ISEE/CICR colloquium
Speaker: Prof. Baolin Tan, National Astronomical Observatories of China, China
ISEE coordinator: Dr. Satoshi Masuda (Division for Integrated Studies)
Date and Time: Oct 30 (Wed), 2019, 16:30-17:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Radio precursors of solar flare
Abstract: Solar flares are the most violent explosions in the solar system, which may release huge amount of energy, accelerate great number of energetic non-thermal particles, and eject hot plasma flows, produce strong disturbance in the interplanetary space and greatly impact on the terrestrial environment. It is one of the main key problems of solar physics to understand the origin of solar flares and to predict their occurrence and evolutions. As we know that the main features of solar flares include the variations of magnetic field in the source regions, radiation of energetic non-thermal particles and the motions of hot plasmas, and these features have much more sensitive response in decimeter and centimeter wavelength of radio observations than in other wavelengths. This talk plans to report the primary results of radio precursors of solar flares by analyzing the observation data of the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) and Nobeyama Radio Spectrometers (NoRP). We find that QPPs with periods of several minutes at radio emissions occurred in the precursor phase of many flare events. Such results may help us to understand the triggering mechanism of solar flares.
57th ISEE/CICR colloquium
Speaker: Prof. Samuel Krucker, University of Applied Sciences Northwestern Switzerland, Switzerland / Space Science Laboratory, University of California, Berkeley, USA
ISEE coordinator: Dr. Satoshi Masuda (Division for Integrated Studies)
Date and Time: Oct 23 (Wed), 2019, 16:30-17:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Solar X-ray Observations with NuSTAR
Abstract: Designed with true focusing optics for extremely high sensitivity, NuSTAR is an astrophysical observatory, but unlike virtually every other high-energy astrophysics mission to date, it is capable of being pointed at the Sun. NuSTAR observes the Sun above 2.5 keV with a sensitivity over 200 times better than that of RHESSI, the previously most capable solar mission in this energy range. This talk will review NuSTAR solar observations focusing on the smallest detectable flares and their importance to coronal heating.
56th ISEE/CICR colloquium
Speaker: Prof. Abraham Chian,
Designated Professor of ISEE, Nagoya University / University of Adelaide, Australia / National Institute for Space Research (INPE), Brazil
ISEE coordinator: Prof. Kanya Kusano (Division for Integrated Studies)
Date and Time: Oct 3 (Thu), 2019, 10:00-11:30
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Title: Nonlinear Dynamics of Space-Earth Environment
Abstract: Space-Earth environment provides a unique laboratory for investigating the fundamental nonlinear dynamics of fluids and plasmas such as Lagrangian coherent structures, vortex-vortex interactions, and intermittent turbulence. In this seminar I will give an overview of some recent theoretical and observational studies of coherent structures and turbulence. First, we discuss the detection of Lagrangian coherent structures in numerical simulation of turbulent dynamos and Hinode observation of photospheric turbulence. Second, we present the simultaneous ground and space observations of an erupting coronal loop which show that the type-II solar radio bursts can be emitted from both upstream and downstream of the shock wave front. Third, we present the observational evidence of magnetically reconnected current sheets in the vicinity of a turbulent front magnetic cloud boundary layer, and discuss the relation between current sheets, turbulence, and magnetic reconnections at the leading edge of an interplanetary coronal mass ejection. Fourth, we report the observation of magnetic reconnection at the interface region of two interplanetary magnetic flux ropes. The front and rear boundary layers of three interplanetary magnetic flux ropes are identified by in situ spacecraft measurements. A quantitative analysis of the reconnection condition and the degree of intermittency reveals that rope-rope magnetic reconnection is the most likely site for genesis of interplanetary intermittent turbulence in this event. The dynamic pressure pulse resulting from this reconnection triggers the onset of a geomagnetic storm. Finally, we discuss the application of recent advances in nonlinear dynamics for the study of atmospheric and oceanic turbulence.
55th ISEE/CICR colloquium
Speaker: Dr. Seth Claudepierre,
Aerospace Corporation & UCLA, USA
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science )
Date and Time: Sep 25 (Wed), 2019, 13:30-15:00
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Title: Empirically estimated electron lifetimes in the Earth’s radiation belts
Abstract: Energetic and relativistic electrons in the Earth’s radiation belt
region are often observed to decay exponentially, suggestive of
pitch-angle diffusion in the lowest eigenmode of the diffusion
operator. We use measurements from the MagEIS instrument on NASA’s Van
Allen Probes to study these decays and calculate the decay time
constants over a wide range of energies (30 keV – 4 MeV) and L values
(L = 1.0-6.5) in the inner magnetosphere. Using an automated routine
to identify decay intervals, we build a large database of events, from
which we compute the average decay times for
near-equatorially-mirroring electrons as a function of energy and L.
We find long electron lifetimes (~100 days) in the inner zone over a
wide range of energies, contrasted with very short, energy-dependent
lifetimes (<10 days) in the slot region, in good quantitative
agreement with prior empirical estimates. The general structure of the
observed lifetime profiles as a function of energy and L is
demonstrated to be consistent with quasilinear pitch-angle diffusion
by various scattering mechanisms, in particular plasmaspheric hiss.
These findings are consistent with recent work that has linked
morphological features in radiation belt observations to the action of
plasmaspheric hiss wave-driven pitch-angle diffusion (e.g., the
“reversed” or “bump-on-tail” energy spectrum and the “wave-like” or
“S- shaped” spectrum). The experimental results also indicate a local
minimum in lifetimes in the inner zone at lower energy (<70 keV),
attributed to enhanced scattering via ground-based VLF transmitters,
and a reduction in lifetimes at higher energy (>1 MeV) and L,
attributed to enhanced EMIC wave scattering. In general, we find that
the observed lifetimes at low L (L<3) are much smaller than
theoretical predictions, ~100 days vs ~1000 days, and discuss possible
explanations for the disagreement between theory and observation.
54th ISEE/CICR colloquium
Speaker: Dr. Mariko Oue,
Stony Brook University, USA
ISEE coordinator: Dr. Taro Shinoda (Center for Orbital and Suborbital Observations)
Date and Time: Sep 24 (Tue), 2019, 14:00-15:30
Place: Research Institutes Building I (ISEE), 6th floor meeting space (617)
Title: Ka-band Radar Polarimetric and Doppler Spectrum Measurements
for Snowbands Along the U.S. Northeast Coast
Abstract: In 2017, the School of Marine and Atmospheric Sciences at Stony
Brook University established a radar observatory for cloud and
precipitation studies (https://you.stonybrook.edu/radar/).
The flagship radar of the SBU radar observatory is a very sensitive,
sophisticated, and well-calibrated Ka-band (35-GHz) scanning
fully-polarimetric radar (KASPR) complemented by two profiling radar
systems operating at W-band (94-GHz, ROGER) and Ku-band
(24-GHz, MRRPro) and X-band dual polarization phased array radar.
All radars are capable of recording radar Doppler spectra.
The facility also has a profiling microwave radiometer and lidar
systems (a scanning Doppler lidar and ceilometers) that observe
the cloud properties and boundary layer conditions.
This facility is designed to observe cloud dynamical and
microphysical characteristics and cloud droplets and ice particle
growth processes at a high spatiotemporal resolution. Here,
an initial analysis of ice microphysics in snowbands observed
in the U.S. Northeast coast using KASPR data polarimetric and
Doppler spectra measurements.
After this talk, I will introduce a radar forward simulator
(the Cloud resolving model Radar SIMulator, CR-SIM) that has
been developed by the radar science group at Stony Brook/McGill
Universities. CR-SIM is licensed under the GNU GPL package
and both the software and the user guide are freely available
to scientific community
(https://you.stonybrook.edu/radar/research/radar-simulators/).
53rd ISEE/CICR colloquium
Speaker: Prof. J.-P. St-Maurice,
Visiting Professor of ISEE, Nagoya University / Professor Emeritus of University of Saskatchewan, Canada / Professor Emeritus of University of Western Ontario, Canada
ISEE coordinator: Dr. Nozomu Nishitani (Center for International Collaborative Research / Division for Ionospheric and Magnetospheric Research)
Date and Time: Sep 19 (Thu), 2019, 13:15-14:15
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: "E region phenomena and what they reveal about ionospheric processes"
Abstract: The ionospheric E region covers the 100 to 180 km altitude region. It can be thought of as a boundary layer in the coupling between the magnetosphere and the ionosphere at high latitudes. It is also the region where the wind-generated Solar Quiet (SQ) current system closes through an electrojet at the equator. As a result of the role played by the E region, strong Hall and Pedersen currents often flow below 130 km in both the equatorial and auroral regions. At high latitudes, the E region plays a key role in the energy transfer from the magnetosphere through the precipitation of high energy particles and Joule heating. The E region currents often generate m-scale ionospheric turbulence, which makes it more difficult to characterize the energy deposition rates. The region is constantly probed by coherent and incoherent scatter radars and has been the target of numerous rocket flights while more indirect observations involve instruments like riometers and magnetometers, among others. I will present some examples of unexpected or poorly understood E region phenomena that have caught my interest over the years. These include episodes of highly elevated electron temperatures near 110 km in both high and equatorial latitudes, a major oscillation of the E and F region during the passage of a solar eclipse, a strange instance of a D region that had higher plasma density than the E region during a major proton event, and the so-called '150-km echoes' at low latitudes and '100-km echoes' at higher latitudes. I will also discuss briefly some of the insights gained from careful studies of E region irregularities observed by coherent radars and rocket instrumentation and discuss their impact on our understanding of the larger system.
52nd ISEE/CICR colloquium
Speaker: Dr. K. D. Leka,
Designated Professor of ISEE, Nagoya University / Senior Research Scientist
at NorthWest Research Associates, USA
ISEE coordinator: Prof. Kanya Kusano (Division for Integrated Studies)
Date and Time: Jul 18 (Thu), 2019, 16:30-18:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Results from the ISEE/CICR Workshop, "Benchmarks for
Operational Flare Forecasting" and Future Prospects
Abstract: As the last solar cycle was coming to an end, an opportunity was
presented to critically assess the performance of operational flare
forecasts, meaning specifically those facilities tasked with providing
standardized, daily (or more frequent) forecasts for energetic phenomena
on the Sun. In October/November 2017 an ISEE/CICR International
Workshop was held examine two questions: (1) "How well do operational
flare forecasting methods presently work?" and (2) "What analysis is
needed to quantitatively answer that question?" The first two papers
resulting from the workshop are now accepted for publication, with
contributions from numerous forecasting facilities around the world. I
will present the analysis approaches and methodology that were developed
by the team for comparing forecast performance results, including the
analysis of different method attributes and implementation details, and
how they impact performance. The results themselves are not surprising
-- many methods demonstrate positive skill but there is no method that
performs well by all metrics -- and there are some indications of what
approaches provide better performance. I will finally briefly discuss
current research directions, and the prospects for improving operational
flare forecasting for the next solar cycle.
51st ISEE/CICR colloquium
Speaker: Prof. Stephan Playfer, Designated Professor of ISEE, Nagoya University / University of Edinburgh, UK
ISEE coordinator: Dr. Hiroaki Menjo (Division for Cosmic-Ray Research)
Date and Time: Jul 18 (Thu), 2019, 15:00-16:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Hyper-Kamiokande & the future of neutrino physics
Abstract: It is planned to construct a 260kton water Cherenkov detector
at a site near the current Super-K detector. I will describe the
design of Hyper-K, and the planned timescale for its construction.
This will be the world?s leading neutrino physics facility with
a broad range of physics topics. Measurements of CP violation in
neutrino oscillations will be made using an upgraded J-PARC beam
and a set of near detectors. Hyper-K will also have the world’s
best sensitivity for proton decay. In neutrino astrophysics precise
measurements will be made of atmospheric, solar and supernova neutrinos,
including a search for supernova relic neutrinos. At the end
I will briefly discuss some longer term prospects for neutrino physics.
50th ISEE/CICR colloquium
Speaker: Dr. Kariyappa Rangaiah, Indian Institute of Astrophysics, India
ISEE coordinator: Dr. Shinsuke Imada (Division for Integrated Studies)
Date and Time: Jun 26 (Wed), 2019, 15:00-16:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Coronal & Photospheric Magnetic Features from Spatially Resolved
Images to Understand EUV & UV Solar Irradiance Variability & their
impacts on Earth's Climate and Space Weather
Abstract: Since the radiative output of the Sun is one of the main driving forces
of the terrestrial atmosphere and climate system, the study of solar
energy raises is of increasing interest. Although the long-term change
in total solar irradiance (the solar energy flux integrated over the entire
spectrum) is considered to be one of the major natural forces of the
Earth’s climate system, the study of extreme ultraviolet (EUV) and
ultraviolet (UV) irradiance variability is equally important in solar physics
and in solar terrestial atmosphere. Indeed, EUV irradiance is the main
energy input for the Earth’s upper atmosphere with important effects on
the ionosphere and thermosphere. The solar EUV and UV fluxes thus play
a major role in Solar-Terrestrial relationships. Understanding their
variability is thus an important issue for space weather and climate
applications.? In this seminar, I will discuss about the EUV & UV
solar irradiance variability using spatially resolved full-disk images
obtained from SDO/AIA/HMI, PROBA2/SWAP/LYRA and Hinode/XRT
space missions and highlight the future research at ISEE.
49th ISEE/CICR colloquium
Speaker: Dr. Jing Chen, Nanyang Technological University, Singapore
ISEE coordinator: Prof. Michihiro Mochida (Division for Meteorological and Atmospheric Research)
Date and Time: Jun 14 (Fri), 2019, 11:00-12:00
Place: Research Institutes Building II (ISEE), 4th floor meeting space (409)
Title: "Atmospheric processing promotes the water uptake by organic-rich biomass burning particles in Southeast Asia"
Abstract: Peatland fires in Southeast Asia have been frequently occurring during the last few decades. A huge amount of aerosol particles have been emitted from these combustions, leading to adverse effects on human health and influencing both environment and climate significantly. These regional and global impacts are closely tied to the aerosol water uptake property, which directly changes the particle size and could dramatically alter aerosol physical and chemical characteristics. However, water uptake by Indonesian biomass burning particles has been rarely investigated in the tropical region.
In this talk, I will address the water uptake by various types of Indonesian biomass burning particles and explore the relationships with their chemical compositions through laboratory combustion experiments. To further investigate the influence of these wildfire-induced haze particles on the regional environment, I will show the corresponding water uptake and chemical data obtained from an in-situ haze observation conducted at Singapore in October 2015 during a pervasive wildfire haze episode. These results will deepen our understanding on the water uptake by both freshly emitted biomass burning particles and wildfire-related haze particles originating from Indonesian peatland fires, thus facilitating more reliable evaluations on the climate effects introduced by these biomass burning particles in equatorial Asia.
48th ISEE/CICR colloquium
Speaker: Prof. Satyavir Singh, Visiting Professor, Kyoto University / Prof. at Indian Institute of Geomagnetism, India
Speaker: Prof. Lynn M. Kistler, Designated Professor at ISEE, Nagoya University / University of New Hampshire, USA
Speaker: Dr. Vania Jordanova, Visiting Professor of ISEE, Nagoya University / Los Alamos National Laboratory, USA
Speaker: Prof. Hisao Takahashi, Instituto Nacional de Pesquisas Espaciais (INPE), Brazil
Speaker: Dr. Valentina Zharkova, Northumbria University, UK
Speaker: Dr. Bjorn Stevens, Max-Planck Institute for Meteorology / University of Hamburg, Germany
Speaker: Prof. M.J. Kosch, South African National Space Agency (SANSA), South Africa
Speaker: Dr. Takanobu Yamaguchi, CIRES University of Colorado Boulder / NOAA ESRL, USA
Speaker: Dr. Daqing Yang, Watershed Hydrology and Ecology Research Division, Environment and Climate Change Canada, Canada
Speaker: Prof. A.V. Koustov, Physics and Engineering Physics,
University of Saskatchewan, Canada
Speaker: Dr. Milija Zupanski, Cooperative Institute for Research in the Atmosphere, Colorado State University, USA
Speaker: Prof. Khan-Hyuk Kim, School of Space Research, Kyung Hee University,
Speaker: Prof. Samuel Krucker, Designated Professor of ISEE, Nagoya University / Prof. at University of Applied Sciences Northwestern Switzerland, Switzerland / Senior Fellow at SSL, University of California, Berkeley, USA
Speaker: Prof. Stephen M. Playfer, Designated Professor of ISEE, Nagoya University / University of Edinburgh, UK
Speaker: Prof. ZhongPing Lee, Designated Professor of ISEE, Nagoya University / University of Massachusetts Boston, Boston, USA
Speaker: Dr. Daniel Philip Stern, United States Naval Research Laboratory, USA
Speaker: Prof. Mark Lester, University of Leicester, UK
Speakers: Profs. Joaquim I. Goes and Helga do Rosario Gomes,
Designated Professors at ISEE, Nagoya University / Professors of the Lamont Doherty Earth Observatory, Columbia University, USA
Title: The contrasting influence of two large revers on the biogeography of phytoplankton communities across the river-ocean continuum
Speaker: Prof. C. J. Pan,
Institute of Space Sciences, National Central University, Taiwan
Speaker: Prof. Ioannis A. Daglis,
Designated Professor at ISEE, Nagoya University / Professor at the National & Kapodistrian University of Athens, Greece
Speaker: Prof. Ondrej Santolik,
Institute of Atmospheric Physics, The Czech Academy of Sciences, Czech Republic
Speaker: Prof. Geeta Vichare,
Indian Institute of Geomagnetism, Navi Mumbai, India
Speaker: Dr. Sergey Tyul’bashev, Pushchino radio astronomy observatory, Lebedev Physical Institute, Russia
Speaker: Associate prof. Jeonghoon Lee, Korea University of Technology and Education
Speaker: Prof. Surendra Kumar Dhaka, Department of Physics, Rajdhani College, University of Delhi, India
Speaker: Prof. Bernhard Kliem,
Visiting Professor at ISEE, Nagoya University / Professor at Institute of Physics
and Astronomy, University of Potsdam, Germany
Speaker: Dr. K. D. Leka,
Designated Professor at ISEE, Nagoya University / Senior Research Scientist
at NorthWest Research Associates, USA
Speaker: Prof Cesar La Hoz,
Emeritus Professor of UiT, The Arctic University of Norway
Speaker: Joseph B.H. Baker
Designated Associate Professor at ISEE, Nagoya University /
Associate Professor at Virginia Tech, USA
Speaker: Dr. Martin Connors
Foreign Designated Professor at ISEE, Nagoya University /
Professor of Athabasca University, Canada
Speaker: Pasha Ponomarenko
Designated Associate Professor at ISEE, Nagoya University /
Professional Research Associate
Institute of Space and Atmospheric Studies
University of Saskatchewan, Canada
Speaker: Keun-Ok Lee
LATMOS/IPSL, UPMC Univ. Paris 06, Sorbonne Universit´es, UVSQ, CNRS, Paris, France Taiwan)
Speaker: C. Z. (Frank) Cheng
(National Cheng Kung University, Taiwan)
Speaker:Jeongwoo Lee
(Foreign Designated Associate Professor of ISEE, Nagoya University / Seoul National University)
Speaker:Prof. Syun-Ichi Akasofu
(International Arctic Research Center (IARC),
University of Alaska Fairbanks (UAF))
Speaker: Dr. Antti E. Kero
Visiting Associate Professor of ISEE, Nagoya University
Sodankyla Geophysical Observatory, University of Oulu, Finland
Speaker:Jozsef Kota(The University of Arizona, LPl,Tucson, Arizona, USA)
Speaker: Prof. Balan Nanan
Visiting Professor of ISEE, Nagoya University /
University of Sheffield, UK
Speaker: Prof. Hisao Takahashi
Visiting Professor of ISEE, Nagoya University /
Instituto Nacional de Pesquisas Espaciais (INPE), Brasil
Speaker: Prof. Rene A. Ong
(University of California, Los Angeles)
Speaker: Prof. Jorge L. Chau Head of the Radar Department, Leibniz Institute of Atmospheric Physics (IAP), Germany
Speaker: Dr. Michael M. Bell (Assistant Professor at University of Hawai`i at Manoa,Associate Professor at Colorado State University (since Fall 2016))
Speaker: Takanobu Yamaguchi (Research Scientist II, CIRES UC Boulder/NOAA ESRL, USA)
Speaker: Dr. J. Michael Ruohoniemi
(Virginia Tech, USA)
Speaker: Dr. Andrew W. Yau (University of Calgary, Canada) Speaker: Dr. Barry Gardiner
(INRA-ISPA, Villenave d'Ornon, France)
Speaker: Prof. Hung-Chi Kuo
(Department of Atmospheric Sciences, National Taiwan University) Speaker: Syun-Ichi Akasofu (Professor of Physics Emeritus, University of Alaska, Fairbanks)
ISEE coordinator: Dr. Masahito Nosé (Division for Ionospheric and Magnetospheric Research)
Date and Time: Jun 18 (Tue), 2019, 14:00-15:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: "Kinetic Alfvén waves in space
plasmas"
Abstract:
The acceleration of charged particles in space plasmas is related to the presence of parallel electric fields. The large parallel electric fields can be generated by solitons/weak double layers or acceleration by lower-hybrid waves. Kinetic Alfven waves (KAWs) have also been proposed to accelerate charged particles. Kinetic Alfvén waves are obliquely propagating low-frequency waves. At large wave numbers, Alfvénic oscillations become dispersive and develop electrostatic character and parallel electric fields to the background magnetic field. There are two types of dispersive Alfven waves: 1. kinetic and 2. inertial. Kinetic Alfvén waves exist when the local Alfvén speed is less than the electron thermal speed (VA <47th ISEE/CICR colloquium
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science )
Date and Time: Apr 23 (Tue), 2019, 16:30-18:00
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Title: “The Development of the Storm-Time Ring Current, and Its Effects on
Wave Generation”
Abstract:
During geomagnetic storms, the plasma sheet becomes enhanced with
O+-rich plasma from the ionosphere. This plasma is then convected
into the inner magnetosphere by an enhanced electric field, creating
the storm-time ring current. Using a combination of satellites,
including Van Allen Probes, Arase, and MMS, we have performed a series
of studies that address how the plasma sheet becomes populated, how
the transport of this population into the inner magnetosphere can lead
to oxygen dominace in the ring current, and what effects the
storm-time ring current has on wave generation. We show that both cusp
outflow and night-side auroral outflow enter the plasma sheet during
the main phase of geomagnetic storms. The relative importance of the
sources to the ring current depends on whether they become
incorporated into the hot isotropic plasma (>5 keV) that dominates the
ring current pressure, and indications are that the cusp source is
able to do this more effectively. Using a superposed epoch analysis,
we show that the ring current during the main phase is asymmetric,
with most of the ions drifting around the dusk side, while the
electrons drift around the dawn side. The O+ pressure peaks at lower
radial distances than H+ pressure during the main phase, and the O+
pressure can be dominant at lower distances. Finally the enhanced
ions drifting duskward during storm leads to EMIC wave generation,
while the enhanced electrons drifting eastward lead to chorus wave
generation. The resulting waves are important for determining the
dynamics of the more energetic electron radiation belts.
46th ISEE/CICR colloquium
ISEE coordinator: Prof. Yoshizumi Miyoshi (Center for Integrated Data Science )
Date and Time: Apr 4 (Thu), 2019, 13:30-15:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: “Geomagnetic Storms: New Insights from Multi-Spacecraft
Observations and Self-Consistent Simulations”
Abstract:
Conditions in the near-Earth space environment, where many space
assets operate, may turn quickly from quiet to hazardous and
geomagnetic disturbances may last for days. The largest variations in
the inner magnetospheric plasma and fields occur during geomagnetic
storms and are related to the intensification of the ring current, the
magnetically trapped charged particles circling Earth between ~2 to 5
Earth radii. Global modeling is a powerful tool to study the dynamics
of these coupled inner magnetospheric populations. We present
simulations from the kinetic Ring current-Atmosphere interactions
Model with Self-Consistent magnetic (B) field (RAM-SCB) developed as
part of the SHIELDS framework at LANL. We investigate the
acceleration, trapping, and loss of energetic particles as they are
transported from the magnetotail to the inner magnetosphere during
several geomagnetic storms. We find increased anisotropies in the ion
and electron velocity distributions due to particle injections and
energy dependent drifts and losses. These unstable distributions
induce the growth of plasma waves which further affect the near-Earth
radiation environment. Model results are compared with in situ plasma
and field observations from the Van Allen Probes and Arase spacecraft
and implications for future model development and new research are
discussed.
45th ISEE/CICR colloquium
ISEE coordinator: Dr. Yuichi Otsuka (Division for Ionospheric and Magnetospheric Research)
Date and Time: Mar 1 (Fri), 2019, 13:00-14:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: "Equatorial Plasma Bubble Occurrence under Propagation of MSTIDs and MGWs"
Authors: H. Takahashi, C.M. Wrasse, C.A.O. Figueiredo, G. Barros, I. Paulino, M. A. Abdu, Y. Otsuka and K. Shiokawa
Abstract:
We observed signature of dynamical processes from troposphere to ionosphere, which might be responsible for seeding of equatorial plasma bubbles. Simultaneous observation of Mesospheric Gravity Waves (MGWs) by OH airglow imager, propagating Ionospheric Disturbances (MSTIDs) and Equatorial Plasma Bubbles (EPBs) by groundbased GNSS receivers, OI 630-nm imager and ionosonde have been carried out in the equatorial and low latitude region of Brazil. On 16-17 September 2015, MSTIDs were
observed over 5 to 25^oS in the afternoon to evening. EPBs started to appear after when the MSTID crossed over the solar terminator at 22:30 UT. Large scale MGWs were also observed at 7^oS and 23^oS.
Besides, a large tropospheric convection system was observed at around 30^oS. Gravity wave ray-tracing of the observed MGWs indicated that the waves were from the troposphere and could propagate upward in the F layer bottom height. These observational and model simulations indicate that the gravity waves in the mesosphere and lower thermosphere (MLT) regions are coming from the troposphere and responsible to
generate MSTIDs in the ionosphere, and therein, generating a perturbation in the F layer bottom height resulting periodic EPBs.
44th ISEE/CICR colloquium
ISEE coordinator: Prof. Kanya Kusano (Division for Integrated Studies)
Date and Time: Jan 16 (Wed), 2019, 15:00-16:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: "Acceleration and transport of energetic particles in flaring atmospheres and their diagnostics from HXR and MW emission"
Abstract: It is well accepted that magnetic reconnection is a primary energy release mechanism which initiates solar flares and produced energetic particles.
In this talk first we explore particle acceleration mechanisms during a magnetic reconnection with a single and multiple X-null points (magnetic islands)
and derive particle energy and pitch age distributions for different magnetic field topologies. The results will be compared with observational evidences of energetic particles in
Coronal top loop sources and in-situ observations of the boundary crossings in the heliospheric current sheet.
Second, we demonstrate that the chromospheric footpoints of HXR and MW emission are formed by particle transport into deeper atmospheric layers in Coloumb collision and Ohmic losses caused by the formation of electric circuit by precipitating and returning electrons. This circuit is shown to be established within 70-100 milliseconds after beam injection from the loop top and to exist as long as the magnetic reconnection on the top lasts. We demonstrate different properties of HXR and MW emission in converging magnetic loops in a presence of returning electrons. We reveal the resulting HXR and MW energy spectra and pitch angle distributions derived from the observation and simulations of HXR and MW intensity and polarisation.
Third, we will also explore different types turbulence occurring during magnetic reconnection and particle transport processes that can lead to secondary acceleration of particles. The turbulence parameters are shown to be linked to the parameters of particle beams formed by primary acceleration whose interference is able of producing this turbulence. Thus, we show that stochastic acceleration in flaring atmospheres is a secondary acceleration process formed by energetic particles accelerated during a magnetic reconnection in given magnetic field topologies.
43rd ISEE/CICR colloquium
ISEE coordinator: Dr. Hirohiko Masunaga (Division for Meteorological and Atmospheric Research)
Date and Time: Dec 25 (Tue), 2018, 15:00-16:30
Place: Research Institutes Building I (ISEE), 6th floor meeting space (617)
Title: "Shallow clouds and circulations"
Abstract:
Shallow cloud systems, in the tropics, have long been the focus of studies trying to constrain Earth’s equilibrium climate sensitivity. and are thought to be important for the climate system through their disproportionate sensitivity to aerosol forcing. Recent work, by our group and others, show them to also be important in idealized studies of convective aggregation, through their radiative cooling of the boundary layer and its influence mass transport in the boundary layer. Both work with simple conceptual models and an analysis of the structure of the inter-tropical convergence zone, as evident in aqua-planet simulations using state of the art-climate models, suggests that similar effects of shallow convection may help explain the very different structure of the ITCZ in these models. Prospects for better understanding shallow clouds, using large-eddy simulation and storm resolving models, also on very large-domains so as to capture their interaction with much
larger scale circulations, as well as from ongoing and planned observations, are outlined.
42nd ISEE/CICR colloquium
ISEE coordinator: Dr. Nozomu Nishitani (Division for Ionospheric and Magnetospheric Research)
Date and Time: Nov 30 (Fri), 2018, 13:00-14:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: "Sprites research in Africa"
Abstract:
Transient Luminous Events (TLEs, also called sprites) are a gas discharge phenomenon in the middle atmosphere initiated by the electric field generated by lightning strikes during large convective thunderstorms. The optical emissions start at ~90 km altitude, descend downwards and are very bright but also very brief. As a result, they are rarely reported by naked eye observation. However, they are relatively easy to observe by night-vision TV cameras. TLEs may come in different forms, e.g. halos, elves, column or carrot sprites, blue or gigantic jets. South Africa is a world lightning hot-spot during summer (December-February) with large convective thunderstorms on a semi-regular basis. We started sprite observation in 2016 and have recorded hundreds of events. In this presentation, based on the optical observations, the maximum altitude, altitude of maximum brightness, altitude as a function of lightning charge moment change, average electron energy, and electric field with altitude within sprites is presented.
41st ISEE/CICR colloquium
ISEE coordinator: Dr. Hirohiko Masunaga (Division for Meteorological and Atmospheric Research)
Date and Time: Nov 20 (Tue), 2018, 15:30-17:00
Place: Research Institutes Building I (ISEE), 6th floor meeting space (617)
Title: "Role of vertical wind shear in aerosol-cloud interactions in marine shallow cumulus clouds"
Abstract:
The microphysical suppression of drizzle in precipitating shallow cumulus clouds has recently been shown to be buffered by cloud deepening as a dynamical response to increased droplet number. In this study, we employ large eddy simulations with a newly implemented two-moment bin microphysics model to revisit the buffering and explore the role of vertical wind shear in aerosol-cloud interactions in trade cumuli. An idealized case with steady large scale forcing and nudged mean wind and aerosol concentration is developed based on a ship measurements over the Sulu Sea of the Philippines in 2012 and corresponding reanalysis data. Quasi-steady state is reached after 30-40 h for all 6 simulations (3 different aerosol concentrations with / without vertical wind shear). Consistent with a previous study, our simulations show a deepening of cloud top and a reduction of cloud fraction for higher aerosol loadings and that the buffering expresses itself in surface precipitation. Simulations with
vertical wind shear produce shallower clouds as well as shallower boundary layers than those without vertical wind shear, resulting in a reduction in surface rain rate as aerosol amount increases. Vertical wind shear imposes two effects: clustering of clouds and evaporation of thin cloud elements. The differences between these simulations are reasonably understood as a competition between these two effects.
40th ISEE/CICR colloquium
ISEE coordinator: Prof. Tetsuya Hiyama (Division for Land-Ocean Ecosystem Research)
Date and Time: Nov 2 (Fri), 2018, 10:30-12:00
Place: Research Institutes Building I (ISEE), 6th floor meeting space (617)
Title: "Arctic hydroclimatic regimes and changes in a warming climate"
Abstract:
Northern rivers transport large amount of freshwater and thermal/geochemistry fluxes to the polar ocean system. Many recent studies document significant variations and changes in discharge, water temperature, and geochemistry characteristics in the large arctic watersheds. Based on recent data analysis and literature review, this presentation synthesizes our knowledge of northern river water and heat fluxes into the Arctic Ocean. It will describe the seasonal cycles of discharge, water temperature, and heat flux from the northern rivers and compare their main features across the pan-Arctic domain. It will also discuss basin specific results, such as statistical analyses and model simulations of historical changes and future projections of freshwater and heat transport processes due to climate variation and human impact, particularly the effects of reservoir regulation. It will also discuss the challenges and opportunities in precipitation/snowfall observations and their impacts to basin hydrology investigations. These topics and results are critical for a better understanding of climatic and hydrologic linkages and variations over the northern regions. They are also important for regional hydrology and climate change investigations, such as basin-scale energy balance calculations, and land-ocean interactions, particularly large-scale ocean water/heat budget and model analyses across the arctic regions.
39th ISEE/CICR colloquium
ISEE coordinator: Dr. Nozomu Nishitani (Division for Ionospheric and Magnetospheric Research)
Date and Time: Oct 12 (Fri), 2018, 13:00-14:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: "Contributions of coherent radars to studies of the near Earth's environment"
Abstract:
The aurora borealis is a regular phenomenon at high latitudes. It is caused by
energetic electrons and protons precipitating into the upper atmosphere from
the near-Earth space. The aurora is only one process amongst a myriad of others
occurring when the solar wind, with the embedded magnetic field, interacts with
the Earth’s magnetic dipole.
In early 1950-th it was discovered that the screens of VHF aircraft-monitoring
radars are hugely polluted by signals that were in abundance whenever aurora borealis
lit the sky. It was hypothesised that the signals are coming from the aurora, and a
new science discipline was born. For a long time, the major emphasis has been on the
reasons for the radar aurora. In 1970s, it was realized that the Doppler velocity of
echoes from aurora, now referred to as the “coherent echoes”, can be used for
measurements of the electric fields and currents in the Earth's ionosphere.
Over the last four decades, coherent radars operating at HF and VHF frequencies
(10-100 MHz) made significant contributions to studies of the high-latitude
processes. One of the most successful coherent radar experiments is the Super
Dual Auroral Radar Network (SuperDARN), launched in 1993 and currently involving
scientists from ten nations.
In my presentation, I will first tell a story of how military radars used for
tracking airplanes evolved into instruments useful for studying the aurora borealis.
I will then review our current understanding of the processes occurring in the near-
Earth space with an emphasis on plasma circulation in the ionosphere and beyond, an
area where SuperDARN contributions are most important. Finally, I will show some
recent results illustrating the advantage of SuperDARN radars in monitoring and
quantifying the near-Earth environment.
38th ISEE/CICR colloquium
ISEE coordinator: Prof. Tetsuya Hiyama (Division for Land-Ocean Ecosystem Research)
Collaborator: Dr. Kazuyoshi Suzuki (JAMSTEC), adopted by the "Computational Joint Research Program (Collaborative Research Project on Computer Science with High-Performance Computing)”, ISEE
Date and Time: Oct 3 (Wed), 2018, 13:30-15:00
Place: Research Institutes Building I (ISEE), 6th floor meeting space (617)
Title: "New directions for development of high-dimensional data assimilation"
Abstract:
Data assimilation refers to a mathematical methodology that combines information from prediction model and observations to obtain an optimal estimate of a system state and its uncertainty. Of special interest is the development and application of data assimilation in high dimensions, often associated with realistic problems in geosciences and engineering. Typical methodologies for high-dimensional data assimilation rely on the use of variational methods, ensemble methods, or their combination referred to as hybrid data assimilation. In their basic form, variational methods have inadequate definition and estimation of uncertainty, while ensemble methods suffer from a severe reduction of degrees of freedom. About 10-15 years ago it was recognized that their combination can produce improvements, leading to development of hybrid methods. Unfortunately, since the combination of variational and ensemble methods is generally based on a mixture of mathematical and empirical arguments, there is no sound mathematical formulation of current hybrid methods resulting in an inconsistent estimation of the optimal state and its uncertainty. In this presentation we will address some of these issues and discuss directions for future development of high-dimensional data assimilation that have a potential to overcome current difficulties. In doing so we will pay special attention to coupled systems data assimilation and non-Gaussian data assimilation. In particular we will describe our work on the development of the Maximum Likelihood Ensemble Filter (MLEF).
37th ISEE/CICR colloquium
South Korea
ISEE coordinator: Prof. Kazuo Shiokawa (Division for Ionospheric and Magnetospheric Research)
Date and Time: Jul 5 (Thu), 2018, 13:30-15:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Large and small scale geomagnetic perturbations
Abstract:
In this colloquium, we discuss two topics: one is interplanetary (IP) shock-associated
large scale magnetic disturbances inside the magnetosphere and on the Earth's
surface, called a sudden commencement (SC), and the other is small geomagnetic
perturbations observed in the form of Pc1-2 EMIC waves in space and on the ground.
During the SC interval, a spacecraft on the dayside magnetosphere observes abrupt
and strong steplike increases in the total magnetic field and a dawnward-then-
duskward electric field perturbation. Such SC-associated magnetic and electric field
perturbations have been considered as hydromagnetic waves. It has been suggested
that they propagate tailward with a fastmode speed. However, electric field
perturbation observed near the midnight is in the duskward direction, indicating
earthward propagation. We discuss whether SC-associated field variations can be
considered as fastmode wave oscillations in the magnetosphere. In the second
topic, we discuss the properties of Pc1-2 EMIC waves observed in space and on
the ground. In the outer magnetosphere (L > 6), we found that only ~10% of
EMIC waves identified in 3-min intervals show high coherence (gamma > 0.7)
between two transverse (δbx: radial and δby: eastward) components. This
indicates that most of EMIC waves observed from a spacecraft are
phase-incoherent waves between δbx and δby. That is, they did not oscillate
with a single frequency. The theory of resonant wave-particle interaction
describes that anisotropic and energetic protons interact with a single
frequency wave by cyclotron resonance at a fixed point in space. Our
observations lead us the fundamental question: can phase-incoherent EMIC
waves interact strongly with energetic protons? If not, the EMIC waves
observed in space do not play a significant role in the loss of energetic
particles, including relativistic electrons, in the magnetosphere.
36th ISEE/CICR colloquium
ISEE coordinator: Dr. Satoshi Masuda (Division for Integrated Studies)
Date and Time: May 14 (Mon), 2018, 16:30-17:30
Place: Research Institutes Building I (ISEE), 3rd floor Lecture Room (301)
Title: Hard X-ray Observations as Diagnostics of Particle Acceleration in Solar Flares
Abstract:
Solar flares are powered by an impulsive release of magnetic energy stored in the solar atmosphere. The release of magnetic energy is heating coronal plasma, but as much as half of the released energy goes into particle acceleration. The acceleration mechanisms that provide these efficient conversions of magnetic energy into supra-thermal particles are currently not well understood. In the past years however, significant progress has been made on the observational side; thanks in particular to hard X-ray observations by Reuven Ramaty High Energy Spectroscopic Imager (RHESSI), a NASA small explorer mission. After an introduction, I will review recent observational results obtained by RHESSI. Furthermore, I will briefly describe future instrumentation such as the hard X-ray instrument STIX on board ESA’s Solar
Orbiter mission and the FOXSI concept that successfully used hard X-ray focusing optics for solar observations.
35th ISEE/CICR colloquium
ISEE coordinator: Prof. Yoshitaka Itow (Division for Cosmic-Ray Research)
Date and Time: May 8 (Tue), 2018, 15:00-16:30
Place: Research Institutes Building II, 3rd floor, RB2-3F Hall
Title: "Matter antimatter asymmetries"
Abstract:
Antimatter was predicted by Paul Dirac in 1928 from relativistic quantum
mechanics, and the positron was discovered by Carl Anderson in 1932 in
cosmic rays. It is not understood why the universe appears to contain large amounts of matter, and almost no antimatter. The laws of physics are almost the same for matter and antimatter, apart from a reversal of charge and spin. Matter and antimatter annihilate into energy (photons), and at high energies equal amounts of matter and antimatter are produced. In 1967 Andrei Sakharov wrote down three conditions for generating matter-antimatter asymmetries in the early universe: departure from thermal equilibrium, baryon number violation and Charge-Parity (CP) violation. I will discuss the latter two of these.
As an example of baryon number violation, proton decay has been searched
for, and the proton is known to be stable for much longer than the lifetime of the universe. Studies of CP violation in the quark sector have been performed by accelerator experiments. While CP violating effects are observed they are much too small to account for the asymmetry of the universe. In the Standard Model they are described by the 3X3 Cabibbo-Kobayashi-Maskawa (CKM) matrix. The study of CP violation in the lepton sector is possible through neutrino oscillations, which are described by the 3X3 Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix. I will conclude with a discussion of the current experiments T2K and NOvA, and the planned experiments Hyper-K and DUNE, which aim to observe CP violation in neutrino oscillations within the next 10-20 years.
34th ISEE/CICR colloquium
ISEE coordinator: Prof. Joji Ishizaka (Division for Land-Ocean Ecosystem Research)
Date and Time: May 1 (Tue), 2018, 11:00-12:30
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Remote sensing of basin-scale primary production: Abandoning the use of chlorophyll concentration
Abstract:
Primary production (PP), a measure of photosynthesis of phytoplankton in the oceans, supports the food web and plays key roles in "biological pump" of carbon. For the vast ocean areas, it has long been realized that satellite ocean-color remote sensing is the only feasible means to adequately quantify basin-scale PP. Because of this importance, a wide range of algorithms have been developed in the past decades to estimate PP based on satellite measurements, with nearly all of them centered on the concentration of chlorophyll (Chl). However, because of intrinsic limitations in estimating Chl from ocean color measurements and the wide range of Chl-normalized absorption coefficient, there are inherent, large, uncertainties in the estimated PP with ocean color data as inputs. In this presentation, I would like to highlight the limitations of Chl based PP models and advocate more robust alternatives for the remote sensing of basin-scale PP.
Keywords: primary productivity, ocean optics, ocean color remote sensing
33rd ISEE/CICR colloquium
Date and Time: Mar 22 (Thu), 2018, 15:00-16:30
Place: Research Institutes Building II, 3rd floor RB2-3 Hall
Title: Understanding Extreme Updrafts and Wind Gusts Using Dropsondes and
Large-Eddy Simulations
Abstract:
Intense tropical cyclones can cause tremendous localized wind damage.
Previous studies have also showed evidence that in intense TCs, small-scale
(< 1km) vortices exist along the inner edge of the eyewall. In this
lecture, I will present a dataset of dropsonde observations of extreme
low-level updrafts and wind gusts, and demonstrate that 10-20 ms-1 updrafts
and 90-100 ms-1 wind gusts are commonly sampled in category 4-5 TCs. I
will then use a large-eddy simulation to show that such extreme updrafts
and wind gusts are closely associated with sub-kilometer-scale vortices.
Finally, I will discuss how we can use “virtual” dropsondes to better
compare simulations to observations, and to understand the limitations of
observed sampling.
32nd ISEE/CICR colloquium
Date and Time: Jan 11 (Thu), 2018, 14:30-16:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (317)
Title: Radio Sounding of Planetary Ionospheres: Examples at Earth and Mars
Abstract:
Radio sounding of space plasmas is well established and there are many ways in which
this can be accomplished.In this seminar I plan to demonstrate three different types of
active sounding at Earth and Mars.In the case of earth, I discuss recent results from
the Super Dual Auoral Radar Network (SuperDARN) which is a network of HF
coherent backscatter radars operating in both hemispheres from the poles to
mid-latitudes.In the coherent scatter process the radio signal is backscattered
by irregularities in the ionosphere although there are other potential sources of
returned signal such as the surface of the planet, groundscatter, meteor
ionisation trails, meteor scatter, and possibly ice-crystals in the cold summer
mesosphere, polar mesosphere summer echoes (PMSE).I will discuss recent
observations of signatures of magnetic reconnection, the effects of magnetic
substorms, as well as travelling ionospheric disturbances and the effects of the
large Earthquake in 2013.At Mars, the Mars Advanced Radar for Subsurface
and Ionosphere Sounding (MARSIS) is one of a limited suite of instruments on
Mars Express (MEx) capable of making observations of the ionosphere at Mars.
The Mex spacecraft has been in orbit around Mars for over 12 years and MARSIS
has been operational now for a complete solar cycle.MARSIS is able to measure
the topside ionospheric profile when in Active Ionosphere Sounding (AIS) mode
while when in Subsurface mode it can also make estimates of the Total Electron
content.I will present new results involving long term trends in the Martian
ionosphere as well as the impact of large scale solar disturbances.
31st ISEE/CICR colloquium
Date and Time: Nov 24 (Fri), 2017, 15:00-16:30
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: The role of the Aleutian Low Pressure System in regulating phytoplankton production and carbon export in the North Pacific Ocean
Authors: Joaquim I. Goes(1), Helga do R. Gomes(1) and Joji Ishizaka(2)
(1) Lamont Doherty Earth Observatory at Columbia University, Palisades, New York, USA, 10964
(2) Division for Land-Ocean Ecosystem Research, Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
Abstract:
The North Pacific Ocean experiences strong climate-modulated seasonal,
interannual to decadal variations in meteorological and physical
oceanographic conditions, which have a profound influence on biological
processes and carbon cycling in the region. Inorganic nitrate, a major
nutrient controlling phytoplankton growth is key to understanding the
export of organic matter out of the euphotic zone. Its supply to the
region is driven largely, by winter convective mixing. Using satellite
data for a 20 year period beginning in 1997, we provide evidence of
strong interannual variations in the supply of inorganic nitrate and
new production in the subarctic Pacific the amplitude of which appears
to be linked to El Nino/La-Nina events in the Equatorial Pacific.
These satellite-based climatologies allow us to make a compelling case
that the primary driver for the observed interannual variations in
biological production across the subarctic Pacific is the intensity
of the winter monsoonal winds, which experiences sharp changes in response
to El Nino/La-Nina-mediated shifts in the position and strength of
the Aleutian Low Pressure System. This presentation will attempt to
establish the mechanistic connections between the onset of El Nino/La-Nina
and changes in the west-east gradient in biological production and carbon
export in the North Pacific Ocean through the use of satellite data.
Authors: Helga do Rosario Gomes(1), Joaquim I. Goes(1), Qian Xu(2) and Joji Ishizaka(2)
(1) Lamont Doherty Earth Observatory at Columbia, Palisades, NY, USA
(2) Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Japan
Abstract:
Two large and coordinated studies, one in the western tropical
Atlantic Ocean which comes under the influence of Amazon River discharge
and the other in the East China Sea under the influence of the Changjiang
River Diluted Water (CDW) are contrasted for their influence on
phytoplankton communities. As the Amazon river flows northwards into
North Atlantic Ocean, nutrients in the discharge and salinity variations
modulate the phytoplankton assemblage along the river-ocean continuum
into three distinct communities. These include a dense mixture of diatoms,
cryptophytes and coastal water Synechococcus spp. in the immediate
plume with diatoms benefiting from the nitrate and the ample silicate
provided by the river. The mesohaline region mid-stream of the plume,
was dominated by a large community of Diatom-Diazotroph (Nitrogen Fixers)
Associations which thrived from the high phosphate concentrations in
nitrate depleted waters. Characteristically, the open ocean community
was dominated by the pico-sized Prochloroccocus and another nitrogen
fixer Trichodesmium. Although salinity appeared to have a substantial
influence on the distribution of different phytoplankton groups, the
phytoplankton community structure and distribution in the Amazon River
Continuum were strongly controlled by inorganic nitrate availability.
In contrast although large populations of diatoms were seen in the
Changjiang Discharge Waters, their growth appears be largely
controlled by phosphate availability, Away from the coast the
river waters are diluted by the Kuroshio waters and in this region,
phytoplankton community was structured by the mixing of various water
masses and the nutrients within them thus producing strong interannual
changes in the phytoplankton community unlike the more invariant
phytoplankton community seen in the Amazon river continuum over the
years.
30th ISEE/CICR colloquium
Date and Time: Nov 22 (Wed), 2017, 13:00-14:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Effect of Kelvin Waves on stratospheric QBO during El Nino periods using ECMWF reanalysis data
Author: C. J. Pan(1) and Uma Das(2)
(1) Institute of Space Sciences, National Central University, Jhongli - 32001, Taiwan
(2) Indian Institute of Information Technology, Kalyani - 741235, India
(Visiting Scientist of ISEE under the SCOSTEP Visiting Scholar (SVS) program)
Abstract:
35-year long dataset of temperature from ECMWF reanalysis has been analyzed
to obtain characteristics of Kelvin waves to understand the effect of El Nino
Southern Oscillation (ENSO) on the Quasi Biennial Oscillation (QBO). Enhanced
Kelvin wave activity is observed during El Nino periods when the phase of the
QBO was easterly. Slow waves of wavenumber one and periods greater than
12 days are the most prominent Kelvin waves in the stratosphere during
these periods, and showed significant wave-mean 5 flow interactions.
Comparison with outgoing longwave radiation (OLR) showed that there is
increased convective activity over the Indonesian region and the East Pacific
region during these periods of enhanced Kelvin wave activity. However, the
rate at which the zero wind line preceding the westerly descended from 10 hPa
to 50 hPa was not quite high, as was observed in the case of the 2009/2010
El Nino period. Careful examination showed that, instead of fixing the initial
height at 10 hPa, if the slope of the zero wind line was calculated from the
height at which the enhanced Kelvin 10 wave activity interacted with the
mean flow, the westerly did indeed descend very fast. Thus, we conclude that
during those El Nino periods when the QBO was easterly, the subsequent
westerly showed an anomalous descent. This study emphasizes the
importance of wave-mean flow interactions in maintaining the large-scale
circulation of the Earth’s atmosphere.
29th ISEE/CICR colloquium
Date and Time: Nov 15 (Wed), 2017, 13:30-15:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Storms, substorms, particles and waves: the quintessence of geospace weather
Abstract:
In this talk we discuss the entanglement of complex dissipative phenomena with
particle and wave dynamics in near-Earth space, which to a large extent define
geospace weather. In particular, we shall discuss the main characteristics of the
two major energetic particle populations in geospace – the Van Allen radiation
belts and the ring current – and their intricate relationship during storms and
substorms. Magnetic storms and magnetospheric substorms are the two major
explosive dissipative phenomena in geospace. Although they share a number of
features, like for example particle acceleration, magnetic field reconfigurations and
auroral displays, they are quite distinct – mainly with respect to their magnitude
and their spatial and temporal extent. A long-standing problem of space physics
has been the relationship between storms and storms – in particular the question
of if (and how) substorms influence storm development and decay.
The storm-substorm relation has been a major research topic for several decades
and is still relevant. We have not yet managed to completely understand the role
of substorms in the build-up of the storm-time ring current.
Furthermore, storm-time substorms also influence another prominent geospace
energetic particle population, namely the energetic electrons of the outer Van
Allen belt. Substorm-accelerated electrons serve as seed population for the
storm-time relativistic electrons, while the anisotropic ring current ion and
electron distributions provide energy for the excitation of a variety of
electromagnetic waves, which control radiation belt dynamics. It is therefore
obvious that substorms play a rather influential, albeit complex role in ring
current and radiation belt dynamics.
28th ISEE/CICR colloquium
Date and Time: Oct 26 (Thu), 2017, 13:30-14:30
Place: Research Institutes Building I (ISEE), 4th floor meeting space (417)
Title: From lightning to chorus
Abstract:
The region of the Van Allen radiation belts is sculpted by the presence of
whistler mode waves, especially by plasmaspheric hiss and chorus emissions.
Substantial evidence exists that plasmaspheric hiss itself can arise from
strong emissions of whistler-mode chorus, generated in the outer zone
equatorial region and propagated to high latitudes and inward, filling thus
the plasmasphere and forming hiss. However the debate on the origin of
hiss is still open to other possibilities: local generation and accumulation or
triggering by lightning generated whistlers.
27th ISEE/CICR colloquium
Date and Time: Oct 27 (Fri), 2017, 13:00-14:00
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Overview of low latitude current systems
Abstract:
Magnetic field recordings at geomagnetic observatories play
important role in understanding the currents present in the ionosphere and
magnetosphere. The electric currents flowing in the dayside E-region are
essentially produced by the ionospheric dynamo due to movement of charged
particles (through their collisions with the neutral wind) across the
Earth’s magnetic field. The solar quiet day (Sq) variation of the
geomagnetic field observed globally during sunlit hours is associated with
two equivalent current loops centered around the focal points at ~30 deg
latitudes, located in each daytime hemisphere. Near the dip equator, very
large eastward currents flow in a narrow strip, are called Equatorial
electrojet (EEJ). Geomagnetic observations commenced in India and rest of
the world almost concurrently. The first magnetic observations in India
were started at Madras in 1822, followed by the recordings at various other
places. Among those, only Colaba observatory has continued uninterrupted
since 1841. The combined observations at Colaba and Alibag provide one of
the longest series of magnetic field data in the world. Important
scientific observations such as dependence of magnetic field variations on
the time of day, season, solar cycle and lunar phase were recorded in the
nineteenth century. However, the available network of observatories is not
sufficient to study the small-scale features of the current systems. This
limitation can be overcome by low-Earth-orbiting satellite measurements. In
past six decades, the understanding of EEJ and Sq current systems has
advanced through the use of ground, satellite and modeling studies. The
presentation will provide a brief overview of the present understanding of
low latitude current systems.
26th ISEE/CICR colloquium
Date and Time: Oct 10 (Tue), 2017, 16:00-17:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (317)
Title: Space Weather from IPS observations at 111 MHz
Abstract:
The report highlights the Pushchino radio astronomy observatory. It presents the main Pushchino radio telescopes operating at wavelengths from centimeters to decameters. The main telescope of the Pushchino observatory is BSA. This radio telescope is underway to study the solar wind and is a radio telescope with the world's highest sensitivity. The main purpose of the report to present different ways to study the solar wind in the meter wavelength range by IPS method and show that using only the method of interplanetary scintillation can be predicted CME.
25th ISEE/CICR colloquium
Date and Time: Jul 14 (Fri), 2017, 15:30-17:00
Place: Research Institutes Building I (ISEE), 5th floor meeting space (517)
Title: Photothermal Interferometry : An alternative tool for measuring light absorbing carbon
Abstract:
Aerosol light absorption is a difficult quantity to measure without interference from the light scattering which dominates the light extinction of atmospheric aerosol. Photothermal interferometric technique is one of the
photothermal spectroscopic techniques utilized to directly measure the light absorption from lab-generated aerosols as well as ambient aerosols.Photothermal interferometric technique usually detects the signal of shift in the interference pattern brought about when the optical pathlength of the probe beam is altered due to the heating of aerosol surrounding the probe beam. Two different type of photothermal interferometers will be introduced.
One is an image based interferometer and the other is a polarization based interferometer. The interferometer used in this study is comprised of mirrors, beam splitters and He-Ne laser. Specifically, a diode laser having 532 nm wavelength is substituted for the large sized Ar-ion laser and is
employed to heat up the aerosol sample. This study is believed to help us to elucidate the mechanism occurring inside the interferometer for aerosol absorption measurement in real time.
24th ISEE/CICR colloquium
Date and Time: Jul 6 (Thu), 2017, 13:00-15:00
Place: Research Institutes Building I (ISEE), 5th floor meeting space (517)
Title: An overview of convective sources and dynamical processes in
shaping the troposphere and stratosphere
Abstract:
Almost over the past two decades, we have made measurements from radars during different convection seasons over Indonesia and India to demonstrate the influence of convection in connecting the lower troposphere to upper troposphere, in general these observations show fine time scale (minutes to hours) features. However, these observations were limited to a particular location. In addition, we have also used COSMIC satellite radio occultations temperature data over the globe covering almost a decade (2006 onwards, still continuing), mainly over tropical latitudes presenting a broad overview of dynamical features, such as influence of ENSO in the lower troposphere and dominance of QBO in the lower stratosphere and interaction at upper troposphere and lower stratosphere (UTLS) region. Temperature analyses for association of
lower and upper troposphere are shown over different regions of the globe having contrast topography namely over Pacific sector, Indian sector, and African sector. Correlation coefficient, taken as a measurement of association, show specific longitudinal differences between lower troposphere (from 1 km to 5 km height) and cold point tropopause (CPT), which is located nearly 16 km height. The Northern and Southern hemispheres show contrast coupling between lower
tropospheric region and the CPT. Land and ocean surfaces are found to contribute in a different way to the correlation coefficient (r) between lower troposphere and CPT. Analyses show symmetrical structure of ‘r’ on both side of the equator over the African region, as data included over land region on both side of equator. Data represent positive correlation (r ~ 0.5) over 15-20 degree latitudes on either side of the equator over African region, suggesting the strong hold of variation of seasonal solar diabatic heating influence over the tropic of cancer and tropic of Capricorn. On the other hand, there is a contrast behavior over the Indian region, ‘r’ is nearly negative (~ -1.0) each year in the southern hemisphere (SH) and positive (~0.4) in the northern hemisphere (NH) with a maxima near tropic of
cancer. Analyses suggest that variability in CPT over different regions of globe show significant seasonal association with the lower troposphere. Thus CPT variability, not only governed by QBO, ENSO, gravity waves and Kelvin wave system as reported in earlier studies rather it also considerably affected by seasonal changes taking place in
the lower troposphere.
23rd ISEE/CICR colloquium
Date and Time: May 15 (Mon), 2017, 16:30-17:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Decay index profile and coronal mass ejection speed
Abstract:
The properties of the torus instability suggest that the decay index of
the coronal field has a strong influence on the acceleration of erupting
flux ropes. For high decay index, the acceleration is concentrated at
relatively small heights and reaches a high peak value. For small decay
index, only slightly above the critical value, the acceleration extends
over a large height range with relatively little variation.
Correspondingly, if only the evolution in the corona is considered, one
expects fast CMEs for high decay index and slow CMEs for small (but
still supercritical) decay index. The former situation is typically
found in compact, complex active regions, while the latter is more
relevant for the quiet Sun. A statistical study of 15 fast CMEs (v >
1500 km/s) and 38 slower halo CMEs (v < 1500 km/s) supports this
concept. It yields a relatively high correlation between CME speed and
the decay index profile of the coronal field estimated by a PFSS
extrapolation, provided some outliers -- slow CMEs from compact and
complex active regions -- can be excluded. The consideration of the
latter cases led us to suggest that part of the flux in their source
regions should be considered as "exterior" flux. Such flux has little or
no influence on the equilibrium in the region's core field but
influences the propagation of flux ropes erupting from the core field. A
parametric simulation study based on the Titov-Demoulin equilibrium of a
force-free flux rope in a quadrupolar external field demonstrates that
exterior flux can slow down and even halt a flux rope erupting from the
core field. This yields a model for confined eruptions solely in terms
of the torus instability (i.e., without invoking the helical kink).
Strong exterior flux leaves a characteristic signature in the height
profile of the magnetic field's decay index. Thus, the decay index
profile may provide a useful indication whether a fast CME can
potentially be formed by a given active region.
22nd ISEE/CICR colloquium
Date and Time: April 24 (Mon), 2017, 16:30-17:30
Place: Research Institutes Building I (ISEE), 3rd floor meeting space (301)
Title: Solar Flares and Space Weather Forecasting
Abstract:
Heliospheric Space Weather is a very complicated system, and Solar Flares
play an important role. Flares can be Earth-Impacting by themselves,
but they also serve as indicators for other phenomena such as Coronal
Mass Ejections and Solar Energetic Particle Events. In this seminar,
I will discuss Space Weather Forecasting with a focus on Solar Flares,
and the need for true forecasting (as compared to "now-casting") methods
for these statistically rare events. I will ask "How well are flare
forecasts doing?", discuss how success is measured, and finally ask
"what is needed next?" in order to improve future Solar Flare forecasts.
21st ISEE/CICR colloquium
Date and Time: March 27 (Mon), 2017, 13:00-14:30
Place: Research Institutes Building I (ISEE), 5th floor meeting space (517)
Title: Tutorial on PMSE and PMSE modification by RF heating
-including recent results-
Abstract:
This presentation is a tutorial on Polar Mesospheric Summer Echoes (PMSE), on multi-
scale observations of PMSE and on the modification of PMSE by powerful Radio Frequency
Heating. Both experiments and theory will be described. The experimental
observations were obtained mostly with the EISCAT radars in Tromso, Norway and the
modification of PMSE was done using the EISCAT Heater also in Tromso. I will describe
the generally accepted mechanism of PMSE based on enhancement of the Schmidt
number. The physics of this mechanism is somewhat involved and more often than not,
not well understood. Thus, I will put special emphasis in making the physics of the
Schmidt number accessible and understandable. I will describe how PMSE responds
to RF heating, both in terms of observations and the proposed theoretical models that
have been largely successful in explaining the observations. However, and
finally, I will present recent new results that the same models fail to reproduce.
20th ISEE/CICR colloquium
Date and Time: February 17 (Fri), 2017, 13:00-14:30
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Large-Scale Structure and Dynamics of the Sub-Auroral Polarization Stream (SAPS)
Abstract:
The Sub-Auroral Polarization Stream (SAPS) is a narrow channel of enhanced
westward ionospheric convection which tends to form just equatorward of the
dusk-side auroral oval during geomagnetic storms. Influences thought to
drive SAPS formation include ionospheric closure of the region-2 field-
aligned currents across the mid-latitude trough, pronounced separation
between the electron and ion auroral precipitation boundaries, and active
thermospheric feedback to magnetosphere-ionosphere coupling. The earliest
observations of SAPS were obtained by low-altitude satellites and incoherent
scatter radars which were only able to provide longitudinally limited views
of the phenomenon. Recent expansion of the Super Dual Auroral Radar Network
(SuperDARN) into middle latitudes has opened up new possibilities to examine
the large-scale structure of SAPS and the coherence of its dynamics over
extended regions of magnetic local time. In this presentation, several case
study events will be presented for which SuperDARN data has provided new
insights into the physics of SAPS. Statistical results will also be presented
which show that SAPS-like events can also occur during non-storm periods,
though their physics may be different. Finally, I will discuss recent
initiatives within the US scientific community to better understand SAPS
through coordinated data-model comparisons.
19th ISEE/CICR colloquium
Date and Time: February 10 (Fri), 2017, 13:00-14:30
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Inversion and Interpretation of Ground Magnetic Data, Including Impulsive Events
Abstract:
The sparse distribution of ground magnetometers has traditionally hampered
interpretation of data they provide. While there are practical limitations on how
many magnetometers can be installed in the world, another limitation on
interpretation is data reduction methods. In the case of substorms, the substorm
current wedge likely carries the most information about the underlying physics.
It is particularly important to be able to determine its parameters, which can in
turn be related to physical changes in the magnetosphere. The simple method
known as Automated Forward Modelling (AFM) allows this, and has recently
been shown to robustly determine field-aligned currents as determined by the
near-global measurements of the AMPERE constellation based on the Iridium
satellites. AFM can also be used to determine currents across a meridian. To
fill a large gap in magnetometer distribution, ten new instruments forming the
AUTUMNX array were installed in the eastern Canadian province of Québec,
forming a dense chain along the east coast of Hudson Bay (near 77º west
geodetic longitude), and a more widely spaced one near 68º. Some subauroral
stations are also in place near major hydroelectric power corridors. AFM can
determine current in this meridian, and the stations also detect impulsive
magnetic field changes, not necessarily associated with substorms. In a few
cases, we have related these to geomagnetic induced currents (GIC), as
measured through harmonic distortion measurements for larger events, by the
electric grid operator Hydro Québec. Preliminary indications are that GIC is most
closely connected to changes in the magnetic Z (downward) component, which
elementary consideration of Faraday’s Law might lead one to expect. However,
verifying this needs a yet denser network, so we are working on low-cost
magnetometers to implement it. Some examples of substorm and GIC data
will be discussed.
18th ISEE/CICR colloquium
Date and Time: February 3 (Fri), 2017, 13:00-14:30
Place: Research Institutes Building I (ISEE), 7th floor meeting space (717)
Title: Effects of refractive index of the ionosphere on characteristics
of SuperDARN echoes
Abstract:
Super Dual Auroral Radar Network (SuperDARN) consists of more than 30
high-frequency (HF, 10-15 MHz) radars which monitor high-latitude
ionospheric plasma circulation in both Northern and Southern
hemispheres. Each of these radars scans an extensive area of the
ionosphere (~55 deg in azimuth and up to 3000-4000 km in range) and
provides estimates of Doppler shift, range and direction of arrival for
signals scattered by irregularities of the ionospheric plasma with high
spatial and temporal resolution. These data are then used for deriving
spatial distribution of the ionospheric electric field at high latitudes
which carries important information about Space Weather. The extensive
range coverage of SuperDARN radars is achieved through bending the ray
trajectories back to the Earth due to decrease of the ionospheric
refractive index with altitude. The signals then are reflected from the
ground back to the ionosphere, and the whole process is repeated again
leading to so-called multi-hop over-the-horizon propagation. While
ionospheric refraction of HF radio waves plays a major role in the
multi-hop scenario, by no means this is the only way the refractive
index affects operations of such systems. Another important effect is
distortion of the Doppler velocity estimate which leads to
underestimation of the ionospheric electric field. This problem became
apparent while comparing SuperDARN velocities with those measured by
other instruments. In order to correct the velocity data, it was
necessary to know the refractive index value along the radio wave path,
which could be estimated in several ways. The optimal solution occurred
to be using SuperDARN own data on the arrival direction of the signal
(elevation). In a process of implementing this approach several other
physical and technical problems have been identified and resolved. This
activity led to significant improvement of radar data quality and
expanded SuperDARN diagnostic capability to measuring main parameters of
the regular ionospheric layers over areas inaccessible to the
conventional instruments like ionosondes.
17th ISEE/CICR colloquium
Date and Time: November 30 (Wed), 2016, 15:00-17:00
Place: Research Institutes Building I (ISEE), 3rd floor meeting room (301)
Title: Heavy precipitation events around Mediterranean Sea and field campaign
Abstract:
During Intensive Observation Period 13 (15−16 October 2012) of the first
Special Observing Period of the Hydrological cycle in the Mediterranean
Experiment (HyMeX), Southern Italy (SI) was affected by two consecutive
heavy precipitation events (HPEs). Both HPEs were associated with multi-cell
V-shaped retrograde regeneration mesoscale convective systems (MCSs).
The life cycle of two MCSs in connection with their dynamic and thermodynamic
environments were analysed using a combination of ground-based, airborne
and spaceborne observations and numerical simulations. Rain gauges revealed
that heavy precipitation occurred in two phases: the first one from 1300 to
1700 UTC (35 mm h–1) was caused by a V-shaped system initiating over the
Tyrrhenian Sea in the early morning of 15 October. Convection was triggered
by the low-level convergence between the south-westerlies ahead of an
upper-level trough positioned over south-eastern France and very moist
southerlies from the Strait of Sicily. The convection was favoured by high
convective available potential energy (1500 J kg–1) resulting from warm and
moist conditions at low levels associated with high sea surface temperatures
in the Sicily Channel. In addition, humidity at mid-level was enriched by the
presence of an elevated moisture plume from tropical Africa, favouring the
efficiency of the convection to produce more precipitation. The second phase
of heavy precipitation (2300 UTC on 15 October to 0200 UTC on 16 October,
34 mm h–1) was caused by a MCS initiating over Algeria around 1300 UTC, which
subsequently traveled over the Strait of Sicily toward Sicily and SI.
Convection was maintained by the combination of large low-level moisture
contents and a marked convergence ahead of the cold front. Unlike other MCSs
forming in the same region earlier on that day, this huge V-shaped system did
affect SI because the strong upper-level flow progressively veered from
southwesterly to south-southwesterly.
16th ISEE/CICR colloquium
Date and Time: November 11 (Fri), 2016, 13:00-14:00
Place : Research Institutes Building I (ISEE), 4th floor meeting room
Title: Driven magnetic reconnection processes
Abstract: In this talk I will discuss the basic idea of driven magnetic reconnection and the development of magnetic reconnection theories. I will then explain the physics of driven magnetic reconnection processes based on the full kinetic model.
Finally, I will discuss the applications in solar flares and coronal mass ejections phenomena and in laboratory magnetic confinement plasmas.
15th ISEE/CICR colloquium
Date and time: November 1 (Tue), 2016, 16:30-17:30
Place: ISEE Research Institutes Building I, Room 301
Title: Study of solar flares inside a large magnetic fan structure with NoRH observations
Abstract: Understanding how solar eruption proceeds is an important step toward the ultimate goal of solar physics and space weather forecast. Although the exact mechanisms for solar eruptions are still under debate, it is generally believed that the key information lies in the characteristic magnetic configuration of source active regions. In this talk I will present an on-going study of two successive solar flares from NOAA AR 12371 that occurred on 2015 June 21. The photospheric magnetograms and coronal EUV images from the Solar Dynamic Observatory (SDO) imply that the active region consists of two sunspots embedded within a strikingly large magnetic fan structure. It is therefore of new interest how the compact sunspot fields were interacting with the extended overlying magnetic structure to produce the such successive flares, one associated with a sigmoid structure and the other, with a halo CME. We analyze the unique dataset from the Nobeyama Radioheliograph (NoRH) operated by Nagoya University to derive information on the primary energy release and high energy particles accelerated during the two flares. While the solar EUV images show a continuous change of the coronal features, the NoRH detected two well separated (>25 min) radio bursts with distinct properties of both spectral and spatial morphologies. We relate the former radio bursts to an impulsive energy release within a confined magnetic structure and the latter to the aftermath of the CME. Our ultimate goal is to figure out the magnetic connectivity change that is responsible for the transition from the confined flare to the eruptive flare within 40 min time interval.
14th ISEE/CICR colloquium
Date and time: October 18 (Tue), 2016, 13:00-14:30
Place: ISEE Research Institutes Building I, 6th floor Meeting Room
Title: The forthcoming Big Ice Age
Abstract:
The so-called “interglacial periods (IGP)” are defined on the basis of the global average temperature (15°C) in 1950, which has no meaning in terms of climate change physics (why 1950 ? and many glaciers still exist). Thus, instead, a new physically meaningful baseline for a long-term climate change is considered. It is the minimum temperature which the earth has experience during last 2 million years or perhaps longer, about 8°-12° C lower than the 1950 baseline (15° C), not too far from the freezing temperature; in fact, it is possible to take 0°C as the physically meaningful baseline. In this view, the earth has experienced successive heat inputs, rather than successive Big Ice Ages during at least 2 million years.
From this point of view, water at the distance of the earth from the sun must be near freezing. It is very fortunate that the present time is near the peak of the successive and impulsive heat inputs, not at the baseline level. Thus, the terms ‘Recovery from the Big Ice Age’ and IGP do not describe climate change adequately and are even misleading.
What is causing the successive impulsive heat inputs ? It is unlikely that CO2 is the initiating cause of the impulsive heat input because the temperature increase precedes CO2 increase during each of the early epoch of the impulsive increase and also is not the main cause of the impulsive increase and the present temperature (more than 90% of the present warming is due to water vapor).
In predicting future climate change, it is more important to study the nature of the impulsive heat input process than the CO2 effects.
13th ISEE/CICR colloquium
Date and time: October 14 (Fri), 2016, 13:00-14:30
Place: ISEE Research Institutes Building I, 7th floor Meeting Room
Title: D-region ionization characteristics inverted from ground based electron density measurements
Abstract:
Three case studies related to ground based estimation of D-region ionization
characteristics are shown: 1) Photoionization during the ESR IPY 1-year run,
2) Electron precipitation inversion from EISCAT VHF data during a pulsating
aurora event and 3) Spectral riometer observation of a solar proton event.
12th ISEE/CICR colloquium
Date and time: October 12(Wed), 2016, 15:00-
Place: ISEE Research Institutes Building I, Room 301
Title: Voyager 1 Observations in the Interstellar Space
Abstract:
There is a broad consensus that, in August 2012, the Voyager-1 spacecraft crossed the Heliopause (HP) and entered into the interstellar space. In the talk I shall briefly describe the Voyager mission,and overview the particle and field measurements of Voyager-1 during and after the HP crossing. Small variations in the galactic cosmic-ray flux will be discussed. The global structure ofour Heliosphere is still debated, there are two alternative views on the Heliotail. I shall discuss how energetic neutral atom (ENAs) of the IBEX spacecraft and the anisotropies of TeV cosmic rays detected in ground based air-shower experiments can contribute to the remote exploration of the heliosphere and help to decide between competing theoretical models.
11th ISEE/CICR colloquium
Date and time: October 7 (Fri), 2016, 13:00-14:30
Place:ISEE Research Institutes Building I, 7th floor Meeting Room
Title: Severe space weather and its relevance to the High-Tech society
Abstract:
Like Earth’s weather space weather sometimes become severe. When it becomes
severe it can cause extensive social and economic disturbances in the high-tech
society by damaging satellite systems and ground systems. For example, an event
such as the Carrington event of 1859 at present times can cause damages costing up
to 1 to 2 trillion US Dollars. The seminar will introduce space weather, address what
determines the severity of space weather as experienced by satellite systems and
electric power grids, suggest indices for forecasting (early warning) severe space
weather (SvSW), and discus the mechanisms of SvSW through modeling the
geomagnetic storms associated with SvSW and simulating geomagnetically induced
current.
10th ISEE/CICR colloquium
Date and time: September 27 (Tue), 2016, 13:00-14:30
Place: ISEE Research Institutes Building I, 7th floor Meeting Room
Title: Ionospheric Plasma Bubble Study in Brazil: Today´s Aspect
Abstract:The ionospheric plasma irregularities (bubbles) in the low to middle latitudes
have been subject of research issues in the last 40 years. Different observation
techniques (ionosonde, VHF radar, optical imagers, GNSS receivers, satellite
beacon etc.) have been used to study different physical parameters of the bubbles.
Simulation models of plasma bubbles have also been significantly progressed in the
last 10 years. Today, we know general characteristics of plasma bubbles, frequency
of occurrence and statistically when and where to happen. Implication of such
ionospheric disturbances to our social infrastructures (GPS positioning systems, for
example) is also well recognized. However, an important matter is still not known
yet, it is “plasma bubble seeding mechanism”, how, where and when it starts.
Some historical survey of the plasma bubble observation (mainly in Brazil) and
today´s interest in its subject will be presented and discussed.
9th ISEE/CICR colloquium
Date and time: September 15 (Thu), 2016, 16:00-17:00
Place: KMI Science Symposia (ES635) <= ES building
Title: The Future of Very High Energy Astrophysics
Abstract:The field of very high energy (VHE) astrophysics had been revolutionized by the results from ground-based gamma-ray telescopes, including the current imaging atmospheric Cherenkov telescope (IACT) arrays: HESS, MAGIC and VERITAS. A worldwide consortium of scientists from 32 countries has formed to develop the Cherenkov Telescope Array (CTA) that will capitalize on the power of this technique to greatly expand the scientific reach of ground-based gamma-ray telescopes. CTA science topics will include the origin of cosmic rays and cosmic particle acceleration, understanding extreme environments in regions close to neutron stars and black holes, and exploring physics frontiers through, e.g., the search for WIMP dark matter, axion-like particles and Lorentz invariance violation.
CTA is envisioned to consist of two large arrays of Cherenkov telescopes, one in the southern hemisphere and one in the north. Each array will contain telescopes of different sizes to provide a balance between cost and array performance over an energy range from 20 GeV to above 100 TeV. Compared to the existing IACT arrays, CTA will have substantially better angular resolution and energy resolution, will cover a much wider energy range, and will have up to an order of magnitude better sensitivity. CTA will also be operated as an open observatory and high-level CTA data will be placed into the public domain; these aspects will enable broad participation in CTA science from the worldwide scientific community.
This talk will review the scientific motivation and capabilities of CTA, provide an overview of the technical design and the status of prototype development, and summarize the current status of the project in terms of its proposed organization and timeline.
8th ISEE/CICR colloquium
Date and time: September 12 (Mon), 2016, 10:30-12:00
Place: ISEE Research Institutes Building I, 3rd floor Meeting Room
Title: Unusual 5-m E region field-aligned irregularities observed from Northern Germany during the magnetic storm of March 17, 2015
Abstract:Coherent E region echoes were observed during the March 17-2015 storm
at mid-latitudes by multi-static wide-field of view radars operating in
northern Germany. Two of the stations operated in a monostatic
configuration while one link was set in bistatic mode. Interferometry made
it feasible to locate the targets. While the radars were built to measure
mesospheric winds from specular meteor echoes, the storm was so intense
that it allowed them to observe auroral E region echoes for more than four
hours. All stations detected numerous examples of narrow spectra with slow
(~180 m/s) and fast (up to 1600 m/s) Doppler velocities. The target speeds
were much faster than the Doppler velocities for the slow narrow echoes
(more than 800 m/s vs 180 m/s) but comparable to the observed Doppler
shift for the 1500 m/s narrow fast types. The narrow types came from
localized horizontal structures 50 to 80 km wide in range. The fast narrow
types came from the upper part of the altitudes associated with
Farley-Buneman waves. The slow-narrow structures were typically from
altitudes lower than 100 km. Unexpectedly, the great majority of the
echoes associated with more ordinary ion-acoustic turbulence had a positive
Doppler shift and came from the east. A companion paper uses these new
observations to re-evaluate the origin of the narrow echoes and of the
asymmetry in the counts. Irrespective of the generation mechanisms, our
observations indicate that a combination of unusually large electric field and
strong precipitation is needed to produce the unusual echoes.
7th ISEE/CICR colloquium
Date and time: August 3 (Wed), 2016, 14:00-15:15
Place: ISEE Research Institutes Building I, 3rd floor Letcure Room (301)
Title: Aircraft Observations of Tropical Cyclones: Past, Present, and Future
Abstract:Tropical cyclones (TCs) are a yearly threat to coastal populations around
the world with heavy rainfall, strong winds, and powerful storm surge.
While our ability to forecast TCs continues to improve on average,
individual typhoons or hurricanes can present significant forecast
challenges. Rapid formation and intensification prove especially
difficult for numerical weather prediction models, producing large
errors in track and intensity at longer lead times of three to five days.
This talk will review recent advances in our scientific understanding
of TCs, with a focus on the insights obtained from aircraft observations.
Though satellites provide the most frequent observations of TCs and
their environment around the globe, direct aircraft measurements are
still a primary tool for revealing and understanding the structure,
intensity, and track of these storms. A review of the history of
operational aircraft reconnaissance and results from field experiments
using research aircraft from 2005 - 2015 will be highlighted. Challenges
to further improvements in forecast skill will be discussed, along with
future directions for observations and research that will benefit Japan,
Hawaii, and other coastal areas affected by typhoons and hurricanes.
6th ISEE/CICR colloquium
Date and time: June 15 (Wed), 2016, 15:00-
Place: Research Institutes Building I, Rm. 617 (6F Meeting Room)
Title: Stratocumulus to cumulus transition in the presence of elevated smoke layers
Abstract:The transition from stratocumulus to cumulus clouds in the presence of elevated light-absorbing smoke layers is investigated with idealized large-eddy simulations. A smoke layer is placed 1 km above stratocumulus top and evolves with the cloud fields over the course of a 3 day simulation. The simulations presented vary the smoke-generated heating and the moisture content of the smoke layer. A control case without smoke is simulated for comparison. On day 2 of the transition, when still above cloud, smoke generates a more broken cloud field than the control case, depending weakly on the strength of the aerosol heating but strongly on the water vapor content in the smoke layer. Following nighttime recovery and contact with the stratocumulus, smoke hinders the transition by strengthening the inversion, limiting boundary layer deepening and reducing precipitation-related breakup. This modulation delays the transition, which may extend the stratocumulus deck westward, with con
comitant implications for climate forcing.
5th ISEE/CICR colloquium
Date and time: March 18 (Fri), 2016, 13:30-15:00
Place: Room 301 of the Institute for Space-Earth Environmental Research
Title: The SuperDARN HF radar technique and new perspectives on geospace
research from mid-latitudes to the polar cap
Abstract: The ionosphere is the region of Earth’s near-space environment
that is most accessible to observation by ground-based instrumentation.
The SuperDARN HF radar technique utilizes coherent scattering by
small-scale density irregularities to observe the irregularities
themselves and to measure the motion of ionospheric plasma. Since the
early 1990s chains of SuperDARN radars have been assembled at mid-,
high, and polar cap latitudes by an international team of collaborators
to take advantage of the sensitivity of the HF measurement technique to
a variety of space weather effects. In this talk I will review recent
developments in the expansion of SuperDARN and discuss research carried
out at Virginia Tech that relates to views of geospace processes that
have been made possible by synthesizing over distributed measurements or
by integrating across different measurement techniques. 4th ISEE/CICR colloquium
Date and time: December 7 (Mon), 2015, 13:30-
Place: Room 301 of the Institute for Space-Earth Environmental Research
Title: Heavy Ion Energization and Outflow
Abstract: The discovery of precipitating energetic oxygen ions from the magnetosphere in the 1970’s [Shelley et al., 1972] prompted a fundamental paradigm shift in our perception of the compositional origin
of the Earth’s magnetosphere. The discovery also heralded an extensive
body of studies of heavy ion energization and outflows based on
satellite, rocket and radar observations over the past four decades. We
discuss our contemporary view on the variety of heavy ion outflows and
their source origins and energization, as well as the consequence of
their transport in the context of magnetosphere-ionosphere coupling and
planetary atmospheric escape.
3rd ISEE/CICR colloquium
Date and time: December 4 (Fri), 2015, 15:00-
Place: Room 606 of the Institute for Space-Earth Environmental Research
Title: Prediction of wind speeds and wind damage risk in forested complex terrain
Abstract: Wind is a major disturbance agent in many forest. It is also the
cause of economically important damage in many boreal forests, and in temperate
and tropical forests affected by storms, hurricanes, or typhoons. Predicting
the risk of wind damage is important for advising forest managers and
planners and for mitigating the impact of storms. A key component of any
risk model is the ability to predict the wind speeds over and within forests.
This is relatively straightforward in homogeneous forests on flat terrain.
However, in most parts of the world the terrain is not flat and in addition
forests are rarely homogenous. Predicting wind speeds in complex forested
terrain is a major current challenge for meteorologists and forest scientists.
In this talk we will present recent measurements of airflow and turbulence
over a forested ridge in the west of Scotland, and over model forests with
different levels of fragmentation in a wind tunnel. We will discuss the
results in comparison to the predictions of airflow models and show how this
new data can help to improve the accuracy of existing forest wind risk models.2nd ISEE/CICR colloquium
Date and time: November 24 (Tue), 2015, 10:30-12:00
Place: Room 617 of the Institute for Space-Earth Environmental Research
Title: Wavenumber-2 Deep Convection in Tropical Cyclones
Abstract: Many radar observations, such as in the Second Miyakojima typhoon
(1966), Typhoon Herb (1999), Typhoon Haitang (2005) and Typhoon Dujuan (2015),
are with cyclonically rotating elliptical eyewall. Interestingly, there were
often the deep convection occurred on the tips of the major axis in the
elliptical eyewall. This paper investigates the structure of boundary layer
pumping and convection in tropical cyclones that have elliptical eyewalls or
polygonal eyewalls. We use the simple approach of a nondivergent barotropic
model for the inviscid flow above the boundary layer (BL), and then use the
associated pressure field (derived from the nonlinear balance condition) to
drive a slab boundary layer model. The BL flow driven by this pressure field is
divergent so that the spatial distribution of BL pumping (updraft on top of BL)
can be calculated. The interaction is one-way in the sense that the overlying
flow drives the BL, but the BL pumping does not feed back onto the overlying
flow. The model calculations are in the Cartesian geometry with double Fourier
pseudospectral method. The model results of maximum BL pumping on the tips of
the major axis of the elliptical eyewall is in general agreement with the
observations. The model also indicates the existence of jet-like high speed
tangential winds upstream the major axis tips in the BL. The formation of BL
pumping (and convergence) in the tip of the major axis is caused by local super-
gradient winds, in a way similar to the dynamics of super-geostrophic winds in
the midlatitude jet exit region. The results highlight the wavenumber-two
feature of the BL radial wind in shock-like structures, which lead to large BL
pumping. Our experiments also indicate that the similar radial profiles and BL
pumping may occur in the tips of the polygonal eyewalls.
1st ISEE/CICR colloquium
Date and time: October 27 (Tue), 2015, 15:00-16:30
Place: Room 301 of the Institute for Space-Earth Environmental Research
Title: Auroral substorms and solar flares
Abstract: Both auroral substorms and solar flares have many close morphological similarities, as well as magnetic energy as their source
of energy. A study of auroral substorms has an advantage of studying
them in terms of the input-output relationship on the basis of ground-
and satellite-based observations. It is shown that the epsilon function
is the power (in watts) of the solar wind-magnetosphere interaction;
auroral substorms are a manifestation of dissipation processes of the
power. Solar flares are examined in a similar way, namely the
input-output relationship on the basis of the epsilon function. In fact,
the epsilon function may be applicable in astrophysical problems. A new
idea of the formationof single (solitary) spots and pairs of spots is
also discussed.