[GEM] THE GEM MESSENGER, Volume 25, Number 32

Newsletter Editor editor at igpp.ucla.edu
Tue Sep 1 13:06:55 PDT 2015


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     THE GEM MESSENGER
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Volume 25, Number 32
September 1, 2015

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1. 2015 Summer Workshop Report: Quantitative Assessment of Radiation Belt Modeling Focus Group
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From: Weichao Tu (wetu at mail.wvu.edu), Jay Albert, Wen Li, and Steve Morley

In the 2015 GEM Summer Workshop, “Quantitative Assessment of Radiation Belt Modeling” (QARBM) Focus Group held five sessions on Monday June 15th and Tuesday June 16th. All of the sessions were well-attended with helpful discussions. There were 39 scheduled talks in total and a few walk-in talks over the 5 sessions, covering a wide range of topics, as listed below:

Session 1 - “Radiation Belt (RB) observations and modeling results”

In the first session eight talks were presented on the observational and modeling results of the acceleration, transport, and loss of radiation belt particles. There were four talks discussing the radiation belt responses during the recent “super storm” on Mar 17, 2015, including the fast diffusion and impenetrable barrier for ultra-relativistic electrons observed by Van Allen Probes, the LFM test particle simulation for ULF waves and electron transport, and the VERB code simulating the MeV electron dynamics. The additional four talks reported, respectively, LFM test particle simulations of RB electron precipitation response to ULF waves, modeling of the “peculiar” pitch angle diffusion of relativistic electrons in the inner belt and slot region using a 2D diffusion code, deep injections of 10s-100s keV electrons observed by Van Allen Probes, and statistics of storm-time RB enhancements vs. depletions showing detailed E and L dependence.

Session 2 - “Various magnetospheric wave characteristics and their global distribution required in RB modeling”

This session focused on characterizing various wave properties that are required as inputs to RB models. Nine short talks were presented, covering ULF waves, chorus and hiss, EMIC waves, magnetosonic waves, and their effects on RB particles. There were three ULF-related talks, covering quantification of the radial diffusion coefficients using Van Allen Probes field data, discussion of the relation between ULF waves and radial diffusion, and an advertisement for the ULF Wave Challenge organized by the Validation & Metrics FG. One talk discussed the relationship between EMIC waves and RB electron precipitations based on data from multiple missions including BARREL, Van Allen Probes, CARISMA, CSSWE, POES, etc. The two magnetosonic (MS) wave talks focused on observational and numerical studies of the electron scattering due to MS waves and the bounce resonance with MS waves. Additional topics covered in the session included global chorus wave distributions using statistical and event-specific models, nonlinear wave-particle interactions, and the effects of wave obliquity on RB energization and losses.

Session 3 - “Seed populations, plasma density, and magnetic field configuration required in RB modeling”

Nine talks were presented in this session focusing on specifying other required inputs for driving RB simulations. There were four talks on the quantification and modeling of the seed populations for radiation belt electrons, including the IMPTAM model, an empirical model based on LANL/GEO data, the quantification using Van Allen Probes data, and the RCM-E simulation. In addition, two talks discussed the Time Domain Structures and the Double Layers associated with electron/ion acoustic waves, and the three talks by the end reported updates and results from the DSX mission, FIREBIRD II, and the CSSWE mission.

Session 4 - “RB "dropout" and "buildup" challenges and Planning for future activities”

In the final independent session of our FG we had a great discussion on the RB "dropout" and "buildup" challenges that we are planning. Due to the large number of presentation requests, a few short talks were scheduled at the beginning of this session. The topics included: recent results from the UCLA reanalysis code, 3D LFM test particle simulations on the October 2012 storm and March 2013 storm respectively, and Van Allen Probes observations of the electron bursts during the March 2015 storm. 

After those talks, we started the discussion on the RB "dropout" and "buildup" challenges by proposing candidate events under four different categories: “storm-time enhancements”, “non-storm enhancements”, “storm-time dropouts”, and “non-storm dropouts”. Three to four candidate events were presented and discussed under each category including details of solar wind drivers, geomagnetic activities, and RB responses. The goal is to select one event from each category based on inputs from the community. After the summer workshop, we sent out an email to the community to collect votes for the challenge events. Based on the responses that were received, we found the votes were exceptionally clear-cut for the storm-time events. While voting was less one-sided for the non-stormtime events, a clear consensus emerged in the votes as well. We will soon announce the final selections for the four challenge events and encourage people to simulate these events with their own models and/or provide data or model inputs that are required to simulate these events. To establish a common basis for simulations and testing, we will also provide a common point of access to the model inputs and data for each of the selected events. By mini-GEM in December 2015, we look forward to seeing results of modeling and quantitative assessment of these selected challenge events.

Session 5 - “Joint session with “Inner Magnetosphere Cross-Energy/Population Interactions” FG”

We finished with a joint session with the IMCEPI FG, since the two FGs have common interest in understanding how plasma waves are generated and how they influence the radiation belt dynamics. In this session, we had eight talks in total, with two talks discussing the quantitative simulations of RB electrons using a 3D diffusion model and the VERB-4D convection-diffusion model respectively, two EMIC-related talks on the generation of EMIC waves and the statistical distribution of EMIC waves from Van Allen Probes data, three talks on the generation of whistler waves using experimental or numerical approaches, and an additional talk on the multi-point observations of ULF waves.


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