SM41C-2492
The role of the large scale convection electric field in erosion of the plasmasphere during moderate and strong storms
Thursday, 17 December 2015
Poster Hall (Moscone South)
Scott A Thaller1, John R Wygant1, Cynthia A Cattell1, Aaron W Breneman2, John W Bonnell3, Craig Kletzing4, Sebastian De Pascuale4, William S Kurth4, George B Hospodarsky4 and Scott R Bounds4, (1)University of Minnesota Twin Cities, Minneapolis, MN, United States, (2)The University of Minnesota, Minneapolis, MN, United States, (3)University of California Berkeley, Berkeley, CA, United States, (4)University of Iowa, Iowa City, IA, United States
Abstract:
The Van Allen Probes offer the first opportunity to investigate the response of the plasmasphere to the enhancement and penetration of the large scale duskward convection electric field in different magnetic local time (MLT) sectors. Using electric field measurements and estimates of the cold plasma density from the Van Allen Probes’ Electric Fields and Waves (EFW) instrument, we study erosion of the plasmasphere during moderate and strong geomagnetic storms. We present the electric field and density data both on an orbit by orbit basis and synoptically, showing the behavior of the convection electric field and plasmasphere over a period of months. The data indicate that the large scale duskward electric field penetrates deep (L shell < 3) into the inner magnetosphere on both the dusk and dawn sides, but that the plasmasphere response on the dusk and dawn sides differ. In particular, significant (~2 orders of magnitude) decreases in the cold plasma density occur on the dawn side within hours of the onset of enhanced duskward electric field. In contrast, on the dusk side, the plasmapause is located at higher L shell than it is on the dawn side. In some cases, in the post-noon sector, cold plasma density enhancements accompany duskward electric field enhancements for the first orbit after the electric field enchantment, consistent with a duskside, sunward flowing, drainage plume.
