*************************** ** THE GEM MESSENGER ** *************************** Volume 23, Number 23 August 21, 2013 ---------------------------------------------------------------------- 1. 2013 Workshop Report from Radiation Belts and Waves (RBW) Focus Group ---------------------------------------------------------------------- From: Jocab Bortnik, Scot Elkington, Yuri Shprits and Craig Kletzing The Radiation Belts and Waves (RBW) focus group enjoyed a particularly large attendance at the 2013 GEM summer workshop, undoubtedly due to the recent launch of the Van Allen Probes mission, and a number of related missions such as BARRELL and CSSWE. We had 6 sessions scheduled to take place on Wednesday June 19th and Thursday June 20th, originally planned for Cathedral Peak but relocated to Salon A due to the large number of attendees. There was a total of 60 speakers over the 6 sessions, thus averaging 10 speakers per session, which was achieved by imposing a nominal 5-minute or 3-slide per speaker rule (a poll of the audience taken at the end of session 6 revealed that this rule turned out to be not as onerous as initially thought, and surprisingly the audience voted unanimously to keep it). A wide range of topics was discussed at the sessions which we cannot cover in detail but only highlight a few selected topics: - The RBW particle challenge: session 1 focused primarily on the results of a challenge initiated in the RBW group, to use a variety of models in order to simulate several preselected storms over the CRRES period. Several modeling groups showed their results, including ever increasing complexity into their modeling, such as radial diffusion, scattering due to chorus, hiss and EMIC waves. First results were shown from the coupled BATSRUS-RAM code, the VERB 4D code, and the K2 model, among others. - Radiation belt dropouts: a big theme this year was understanding the causes of radiation belt dropouts. Various projects highlighted different ideas such as electron loss due to magnetopause shadowing together with outward radial diffusion, precipitation into the atmosphere due to ULF wave action, and precipitation loss due to chorus and hiss waves. This was supported by a number of observational studies using NOAA/POES satellites, THEMIS and of course Van Allen Probes. Several studies seem to suggest that dropouts are not accompanied by precipitation loss. Notably, first results were shown of the student-built CSSWE satellite which had been successfully launched in Sept 2012. - Radiation belt acceleration: the acceleration of radiation belt electrons to relativistic energies is an ongoing area of intense research, with much debate about the dominant mechanisms that cause this acceleration. Notably, results were reported from the Van Allen probes that showed compelling evidence of phase space density peaks forming at low L-shells, in the aftermath of a storm. Interestingly, evidence from the Van Allen Probes has also been presented of non storm time enhancements of radiation belt particles, apparently not associated with chorus waves. - wave excitation and wave particle interactions: a number of studies focused on the detailed behavior of particles using test-particle scattering, for instance extremely rapid scattering was shown to occur when interacting with EMIC, and the trapping limit of protons was investigated due to field line curvature. New models were shown that simulated wave excitation and growth using hybrid-PIC codes, and yet other models showed the often non-diffuse transport of particles due to ULF waves (modeled with MHD codes). A direct, detailed observation of wave-particle interaction from the Van Allen Probes was shown, with pitch-angle distributions collected at up to 1000 samples per spin. - RBW challenges: while the particle challenge is now in a mature phase, and will continue into the final year of the RBW focus group, a new wave-excitation challenge has been initiated whose focus is modeling the excitation of a single chorus element, given a standard set of input parameters. Initial results will be presented at the GEM mini-meeting at the 2013 Fall AGU, and final results will be discussed at the 2014 GEM summer workshop. +-------------------------------------------------------------------+ | The GEM Messenger is the electronic newsletter for the | | NSF GEM Program and Workshops. | | | | Editor: Peter Chi, GEM Communications Coordinator | | E-mail: | | | | To subscribe GEM Messengers, send an e-mail message to: | | | | with the following command in the body of your e-mail: | | subscribe gem | | To remove your e-mail address from the list, the command is: | | unsubscribe gem | | | | GEM Messenger is also posted online (via NewsFeed) at | | http://heliophysics.blogspot.com and | | http://www.facebook.com/heliophysics | | | | Back issues are available at ftp://igpp.ucla.edu/scratch/gem/ | | | | URL of GEM Home Page: http://aten.igpp.ucla.edu/gemwiki | | Workshop Information: http://www.cpe.vt.edu/gem/index.html | +-------------------------------------------------------------------+