[GEM] THE GEM MESSENGER, Volume 27, Number 43

[Newsletter Editor]

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     THE GEM MESSENGER
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Volume 27, Number 43
Oct.13,2017

Announcement submission website: http://aten.igpp.ucla.edu/gem/messenger_form/

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Table of Contents

1. 2017 GEM Workshop Report: Inner Magnetosphere Cross-Energy/Population Interactions (IMCEPI) Focus Group

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1. 2017 GEM Workshop Report: Inner Magnetosphere Cross-Energy/Population Interactions (IMCEPI) Focus Group
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From: Yiqun Yu, Colby Lemon, Mike Liemohn, Jichun Zhang (yiqunyu17 at gmail.com)

This year, our IMCEPI FG organized 3 breakout sessions with 16 presentations in total, including one session planning our Challenge topic of spacecraft charging. All sessions were well attended with more than 50 audiences in the room. The goal of our FG is to bring together researchers to address the broad questions of interest to the inner magnetosphere FG: the coupling processes across different inner magnetosphere populations and M/I systems. The three breakout sessions focused on (1) the particle dynamics in the inner magnetosphere and their coupling to the ionosphere, (2) the wave dynamics in the inner magnetosphere and effects on the particle dynamics, and (3) the challenge topic related to the ring current energy populations.

(1) Session on the particle dynamics in the inner magnetosphere and coupling to the ionosphere
We had 6 speakers presenting recent advances on the ring current energy particle dynamics from both observational and modeling perspectives. In specific, Cristian Ferradas reported the temporal evolution of ion spectral structures during a storm time through both observational and modeling methods. Chao Yue statistically studied, based on Van Allen Probes data, the pitch angle distributions for different energy protons in the inner magnetosphere and found pancake PAD, field-aligned PAD, and butterfly PAD for low-, warm-, and high-energy protons respectively. Asymmetry was also found in the equatorial plane. Philip Fernandes on the other hand showed global distribution of O+/H+ ratios as function of geomagnetic activity, again based on years of Van Allen Probes observations. Consistency as well as new distribution features was discovered as compared to earlier studies. Thiago Brito modeled ring current ions fluxes at GEO and their trajectories from plasmasheet during substorms using backward particle tracing methods and found reasonable agreement with observations. The coupling of the magnetospheric dynamics to the ionosphere, e.g., particle precipitation, is also discussed. For example, George Khazanov presented the formation of superthermal electron precipitation in the MI coupling system, and Yiqun Yu reported their recent advancement in the modeling of auroral conductance in global models with the help of magnetospheric electron precipitation.

(2) Session 2: wave dynamics in the inner magnetosphere
This session mainly focused on plasma waves in the inner magnetosphere and their impact on the plasmasphere/ring current/radiation belts.  We had 6 speakers presenting various plasma waves in the magnetosphere and their effects in the magnetospheric particle dynamics. Mykhaylo Shumko reported the microburst scale sizes derived from FIREBIRD-II observations. Kyungguk Min talked about the ion Bernstein instability generated from ion ring distribution from both theoretical and modeling perspectives. Anthony Saikin statistically examined the global distribution of EMIC waves and analyzed the plasma conditions that favor the EMIC wave excitation. Zhaoguo He also analyzed the EMIC wave generation during a substorm event using multiple satellite observations. Sam Bingham talked about the seed populations of whistler mode waves during two types of storms: ICME or CIR-driven. Finally, Run Shi related the plasma injection convection with the low-frequency hiss observed in the inner magnetosphere. All the above presentations have revealed the variety and dynamics of different plasma waves and their close association with ambient plasma conditions and dynamics as well as the subsequent impact on different populations.

(3) Discussion of the challenge topic of spacecraft charging: 
We discussed our challenge topic on “spacecraft charging” that is associated with ring current particles dynamics. Since last GEM workshop, we initiated such a challenge topic and March 17, 2013 event was selected as the first event to work on. This year, several speakers shared their thoughts and stepped further, with discussion emphasizing the metric to be compared among different models. 

Lutz Rastaetter firstly gave an overview of the CCMC facility on calculating the spacecraft charging using the precipitation flux at designed altitude. Then, ring current modelers from three different groups presented their own modeling capability and results. For example, Vania Jordanova presented the capability of RAM-SCB and suggested the effect metric/science predictions from moldering results. Colby Lemon reported the modeling results using the RCM-E model and compared to ring current particle observations with good agreement. Alex Glocer finally talked about CIMI model and proposed the skill scores as the measure of the performance of different ring current models. 

Inputs from the audience also provided valuable discussion. For example, (a) Electric potential charging on the spacecraft is a dangerous situation, which is worthy examination; (b) A unified list of parameters to be compared between the data and the models is needed. Plans of future meetings were also discussions. A post-GEM discussion has carried out through emails and the models are currently aligned up to determine the differential flux at the same energy grids.


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