Table of Contents ====================================================================== 1. Workshop Report: Plasma Entry and Transport into the within the Magnetotail Focus Group 2. Workshop Report: Near-Earth Magnetosphere: Plasma, Fields, and Coupling Focus Group ====================================================================== *************************** ** THE GEM MESSENGER ** *************************** Volume 21, Number 24 October 4, 2011 ---------------------------------------------------------------------- 1. Workshop Report: Plasma Entry and Transport into the within the Magnetotail Focus Group ---------------------------------------------------------------------- Conveners: Simon Wing, Jay Johnson, and Antonius Otto Summary of the PET FG PET FG had two sessions on Monday Jun 27, 2011: (1) Summary and (2) Future planning. PET FG ended this summer. The summary session summarizes the accomplishments and progresses made in the plasma entry and transport in the plasma sheet during life of PET FG. The future planning session discusses what the community would like to do in the future. We would like to especially thank two of our speakers, Joachim Birn and Joe Borovsky, who adhered to their commitments to give talks in our session despite the call for mandatory evacuation of their homes that came in the middle of our first session. 1. Summary * Jay Johnson, Antonius Otto, and Simon Wing highlighted the major accomplishments during the life of the FG. Although it was not possible to list all accomplishments and progresses during the lifetime of the focus group, a more detailed and complete description will be released in our report to GEM in the fall of 2011. Among other accomplishments have been: a special session on entropy at the 2008 Fall AGU Meeting, a special section of JGR on entropy published in 2009-2010, and the PET2009 workshop held in Fairbanks, AK. * Joachim Birn summarized his work on MHD simulation of plasma bubbles in the magnetotail. When the bubbles reached the near Earth region, field-aligned currents are launched. * Larry Lyons summarized the accomplishments of his group during the life of PET FG. He showed the interplay of the large and mesoscale structures of the electrodynamic M-I coupling. Large scale PBI and streamers lead to a mesoscale flow channel that swings around the Harang discontinuity, which can lead to substorms or equtorial arcs. * Joe Borovsky examined the specific entropy, s, in the radiation belt. He derived a formula for s for relativistic case. Energetic electrons in the radiation belt have roughly the same adiabats as those in the magnetotail. He suggested that the radiation belt electrons leak out to the magnetotail. * Chih-Ping Wang summarized his work that shows that Vy fluctuations give rise to the diffusion of the solar wind origin cold particles from the flanks to the center of the plasma sheet. He also showed some statistical properties of Ti/Te ratio for cold and hot population. Ti/Te ratio for cold population is higher (~10) than that of hot population (~4) and Ti/Te ratio of the cold population is similar to that of the magnetosheath. * Vahe Peroomian summarized his work with LSK simulation on three events. In a CME storm event of 28 Oct 2001, LSK density agrees well with that observed by LANL satellite. In another CME storm event on 17 Apr 2002, LSK density again agrees well with that of IMAGE HENA observations. During IMF Bz northward turning, the magnetosheath ions have direct access to the dawnside inner magnetosphere. During storms, magnetospheric ions can move earthward and either exit the magnetosphere or populate the ring current. * Jimmy Raeder presented his work with open GGGCM MHD simulation during northward IMF. MHD density agrees well with that observed by THEMIS satellite. Poleward of the cusp reconnection occurs leading to formation of a thick cold, dense, plasma layer inside the dayside magnetopause. Moreover, reconnection does not occur simultaneously in both hemispheres, leading to asymmetry in flows at the magnetopause. During southward IMF, the cold dense layer is not found. * Kyung Joo Hwang examined KHI and KH waves during various IMF confiurations. Southward IMF should suppress KH waves while dawnward IMF leads to KH waves at high-latitudes. Sunward IMF leads to FTE at the boundary layer. * Mark Engebretson presented observations of PC1 waves in the high altitude mantle/lobe region, which can be associated with streaming O+ in the tail. IMF Bz was southward and By was large during this event. However, similar O+ distribution was observed in the tail without the presence of the waves. This leads to the question of what role PC1 plays in the transport of O+ from ionosphere to the plasma sheet. * Wendy Mata summarized her modeling work on the evolutions of hot ions during a prolonged period of northward IMF. Her model traces ions in Tsyganenko magnetic field model and uses statistical Geotail ion distribution at the model boundary. She found a qualitative agreement with Wing et al. [2005] observations. * Jian Yang examined bubble injection in the RCM-E simulation. In the simulation, bubbles push the the inner edge of the plasma sheet earthward leading to a condition that resembles dipolarization. Bubbles can create finger like structure due to interchange instability, which leads to small field-aligned current strucures in the ionosphere. Wide bubbles would break up into small pieces at the inner edge of the plasma sheet and bubbles play a role in particle acceleration. * Ying Zou summarized her work with NORSTAR high resolution observations of electron and proton aurora. She used 6300 A for electron aurora. During quiet time, the equatorward boundaries of the electron and proton aurorae almost coincide. During active time, the separation of the two boundaries widen. There are local time variations. 2. Future Planning Antonius Otto led a discussion on what the community would like to do in the future. Antonius Otto, Jay Johnson, and Simon Wing proposed an FG that focuses on the invariant in the processes along the path from solar wind to plasma sheet. The invariant includes entropy, but is not limited to entropy alone. The attendees gave some suggestions on how to improve the FG. A poll was taken and a large majority support the creation of such focus group. ---------------------------------------------------------------------- 2. Workshop Report: Near-Earth Magnetosphere: Plasma, Fields, and Coupling Focus Group ---------------------------------------------------------------------- Conveners: Sorin Zaharia, Stan Sazykin, and Benoit Lavraud This focus group seeks to improve physical knowledge and modeling capabilities of the near-Earth magnetosphere (NEM, the region that spans the inner magnetosphere and the inner plasma sheet in the tail, within roughly 10 RE from Earth) and its coupling with the outer magnetosphere. The focus group now enters its final year. At the 2011 summer workshop, the NEM focus group held two sessions. The great majority of the 16 presentations were modeling studies, with most using data for assessing how well different models reproduce the physics of the inner magnetosphere. This, perhaps, serves to indicate that a lot of this focus group’s work has been converging on coming up with inner magnetosphere modules, crucial components of a future GGCM. The 16 presentations focused on one or more of the following common topics: (1) Role of magnetic field computed self-consistently with the particle pressure distribution in inner magnetospheric models. Work with the RAM-SCB (V. Jordanova, Y. Yu), RCM-E (C. Lemon, M. Gkioulidou, C.P. Wang, and M. Chen), and the IMPTAM (N. Ganushkina) first-principles codes shows that when self- consistent magnetic fields are included (typically in force balance with particle pressure), the resulting injection of plasma sheet material into the stormtime ring current is weaker, as compared to simulations with non-self-consistent magnetic fields. (2) Mechanisms of particle injection into the ring current during magnetic storms. There was a vigorous debate on the exact mechanism of particle injection into the ring current. While all models are able to reproduce ring current particle flux increases during storms through particle adiabatic energization/transport, the effect of “magnetic shielding” (see topic 1 above) may require additional physics, such as assumed strong localized inductive electric fields associated with plasma “bubbles” (J. Yang). There is presently no general agreement and work is under way in this area. (3) Data-based prescription of the plasma sheet source for ring current models on the outer boundary. Specifying the boundary conditions on plasma sheet fluxes for ring current models is crucial to understanding the physics of storms and substorms. A number of approaches were presented, such as specifying plasma moments based on THEMIS data (C.P. Wang, M. Gkioulidou, J. Yang), inferred from TWINS ENA images (M. Chen), based on LANL MPA fluxes (V. Jordanova, Y. Yu), or using statistical data-based plasma sheet models (S. Sazykin). (4) Ability to reproduce the measured Dst index, ENA images, charged particle fluxes, and magnetic field perturbations during storms with modern inner magnetospheric models. This is one of the central aspects of the focus group, and a number of speakers (N. Ganushkina, M. Chen, C. Lemon, C.P. Wang, S. Sazykin, V. Jordanova, J. Yang, A. Glocer, M. Liemohn, J.C. Zhang, R. Ilie, Y. Yu) presented their latest results and challenges. (5) Inclusion of the physics of the inner magnetosphere in global magnetospheric (MHD-based) models. When ring current models such as RCM, CRCM, or RAM are coupled to global MHD-based codes, the physics of the inner magnetosphere (such as large particle pressure increases during storms and electric field shielding of low latitudes by the region-2 Birkeland currents) affects the outer magnetosphere and its interaction with the solar wind. Three talks in the session addressed how these inner magnetospheric effects influence the polar cap potential saturation (D. Welling) and ring current injection during storms (A. Glocer and M. Liemohn). A heated discussion following talks by R. Strangeway and S. Zaharia raised the more general issue of the possibility of reconciling fluid and kinetic formalisms in the inner magnetosphere. At the coming mini-GEM workshop in December 2011, the focus group will continue to discuss ways to productively wrap up the group in 2012, namely, through a modeling challenge using the participating models and data-based results, and ways to document inner magnetospheric modules with the current status of their development. +-------------------------------------------------------------------+ | To subscribe GEM Messengers, send an e-mail to | | | | with the following command in the body of your e-mail message: | | subscribe gem | | To remove yourself from the mailing list, the command is: | | unsubscribe gem | | | | To broadcast a message to the GEM community, please contact | | Peter Chi at | | | | Please use plain text as the format of your submission. | | | | 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 | +-------------------------------------------------------------------+