[GEM] THE GEM MESSENGER, Volume 26, Number 35

[Newsletter Editor]

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     THE GEM MESSENGER
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Volume 26, Number 35
Sep.07,2016

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Table of Contents

1. The Maha Ashour-Abdalla Scholarship in Space Physics

2. 2016 GEM-CEDAR Workshop Report: Dayside Kinetic Processes in Global Solar Wind-Magnetosphere Interaction Focus Group

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1. The Maha Ashour-Abdalla Scholarship in Space Physics
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From: Jean Berchem (jberchem at ucla.edu)

On Friday September 9, UCLA will celebrate the life of Maha Ashour-Abdalla, who died May 1, 2016.  The celebration will be held at UCLA’s Faculty Center starting at 4:00 pm. 

In lieu of sending flowers, contributions are requested to the Maha Ashour-Abdalla Scholarship in Space Physics, which is managed by the American Geophysical Union. 

The scholarship will encourage and support women who are starting graduate studies in space physics. 

To contribute, go to http://giving.agu.org/campaign/vcc/ and choose the Maha Ashour-Abdalla Scholarship Fund from the “Student Grants, Scholarships, Activities” drop-down menu. 

If you prefer, you may send a check, payable to the American Geophysical Union and with the note “Ashour-Abdalla Fund” on the memo line, to: Development Department, American Geophysical Union, 2000 Florida Avenue NW, Washington, DC 20009.


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2. 2016 GEM-CEDAR Workshop Report: Dayside Kinetic Processes in Global Solar Wind-Magnetosphere Interaction Focus Group
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From: Heli Hietala, Xochitl Blanco-Cano, Gabor Toth, and Andrew Dimmock (heli at igpp.ucla.edu)

The Dayside Kinetics FG held four joint sessions during the Summer 2016 GEM-CEDAR Workshop. The Tuesday (06/21) session on “Dayside magnetopause processes and transport” held together with Magnetic Reconnection FG and Transients FGs is summarized in the Magnetic Reconnection FGs report, and the Wednesday (06/22) session on “Magnetospheric signatures of dayside transients” held with UMEA FG and the Transients FG is summarized in the UMEA FGs report.

Thursday 06/23:
Kick-off session of the first dayside modeling challenge
joint with Modeling Methods and Validation FG

Heli Hietala introduced the new Dayside Kinetics focus group, co-chairs, and overview of the challenge. We wish to start this new focus group on "Dayside Kinetics" with a modeling challenge where, after agreeing on a short interval of steady solar wind input conditions from the first MMS dayside season, we will conduct comparisons of the various dayside phenomena. The aims of the challenge are to (i) Collect coordinated in situ and remote observations to assess the dynamics of the magnetospheric system and for model validation; (ii) Quantify agreement/disagreement between datasets and models; (iii) Determine reasons for data/model, model/model, and data/data differences; (iv) Advance our understanding of multi-scale plasma processes and their role in SW-magnetosphere interaction.

First, we had three presentations on different approaches to including kinetic effects in global simulations. Sanni Hoilijoki presented the global hybrid-Vlasov simulation model Vlasiator that describes ions as six dimensional velocity distribution functions and electrons as charge-neutralizing fluid. Global 5 dimensional (2D-3V) show that Vlasiator can generate important features of solar wind-magnetosphere interaction, for example, oblique 30s foreshock waves, magnetosheath mirror mode waves and multiple X-line and FTE formation at the dayside magnetopause. Yuxi Chen presented MHD-EPIC - an MHD simulation with an embedded particle-in-cell (PIC) model - and its 2D and 3D applications for Earth's dayside reconnection. Crescent phase space distribution was found near the reconnection site, and they also demonstrated that the global structure of dayside reconnection does not change much with ion mass. Amitava Bhattacharjee presented integration of kinetic effects in multi-fluid global simulations, discussing different closure schemes and the 5-moment and 10-moment models.

Second, we had three presentations on available observations. Naritoshi Kitamura gave an overview of two good conjunction events between Geotail and MMS on 2 October 2015 (decay of mesoscale FTE during quasi-continuous spatially extended reconnection at the magnetopause [Hasegawa et al., GRL, 2016]) and 18 November 2015 (the magnetopause reconnection line shifts toward the winter hemisphere for southward IMF [Kitamura et al., GRL, 2016]). Heli Hietala presented a list of THEMIS-Cluster-Geotail dayside conjunctions that offer a possibility to observe foreshock/bow shock, magnetosheath, and magnetopause simultaneously. She also noted that ground-based observatories can offer support in resolving/validating the global picture. Andrew Dimmock gave a summary of a data analysis tool [Dimmock et al, 2013], which compiles large datasets of in-situ measurements used for either statistical mapping or analysis. He discussed how these large databases could be generated for upstream criteria comparable to model input conditions facilitating new model-data comparison studies.

Third, we had a vibrant discussion among the 30-40 session participants (approx. 50/50 observers and modelers) on the science priorities, specs and metrics of the challenge. Another important subject of discussion was determining the most optimal and feasible approach to comparing experimental and simulated datasets. We discussed the possible merits of three, 30-45 minute runs with different geometries: a southward IMF polar plane run, a northward IMF polar plane run, and an equatorial plane run. We discussed the pros and cons of metrics including FTEs, magnetosheath waves and turbulence (power spectra, thin current sheets, heating), foreshock and bow shock generated transient structures, magnetospheric effects (excited magnetospheric waves and energetic particles) and the properties of the magnetopause reconnection diffusion region.  

Friday 06/24: 
Kinetic and transient processes in the foreshock, bow shock, and magnetosheath
joint session with Transient Phenomena at the Magnetopause and Bow Shock and Their Ground Signatures FG

Kinetic effects throughout the dayside magnetosphere are driven to a large extent by an array of local and external transient phenomena. The purpose of this joint session was to determine how results from these focus groups could be combined to understand these effects on the dayside system from a global perspective.

Terry Liu showed THEMIS observations of a new ion and electron foreshock upstream of a foreshock bubble's shock. Foreshock bubble's shock could be an additional accelerator and a particle source for the parent shock acceleration. Sanni Hoilijoki and Heli Hietala presented, on behalf of Yann Pfau-Kempf, recent results obtained with the hybrid-Vlasov model Vlasiator. Magnetosheath perturbations are found to deform the bow shock so that transient foreshock-like field-aligned ion beams form, a scenario supported by Geotail observations. Heli Hietala presented ARTEMIS observations of ULF wave growth in the foreshock at lunar distances. The growth rate obtained from the two spacecraft measurements, as well as the other properties of the waves, match well the results of a dispersion solver that uses the observed ion beam distribution as an input. Andrey Samsonov presented a method for incorporating kinetic foreshock effects into a global MHD model. They simulated four events with very distant subsolar magnetopause crossings that occurred during nearly radial IMF intervals lasting from one to several hours. They changed the solar wind boundary conditions for a global model assuming that the density and velocity in the foreshock cavity decrease to ~60 % and ~94 % of the respective ambient solar wind values during intervals with small IMF cone angles. Christina Chu presented a hot flow anomaly (HFA) analog simulated in BATS-R-US and observations of how it affected the magnetosphere. This work will be used to analyze ground signatures observed with HFAs. Hui Zhang presented a statistical study to determine what kinds of discontinuities are more efficient to generate HFAs. Their results show that magnetic field on at least one side of the interplanetary discontinuities has to be connected to the bow shock in order to form HFAs. Discontinuities with large magnetic shear angles are more efficient to form HFAs. Current sheets with thickness from 1000 km to about 3162 km are more efficient to form HFAs. HFAs are more likely to form when the reflected flow from the bow shock is along the discontinuity.


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