A Statistical View of the Effect of Density Asymmetry and Guide Field on the Structure of the Reconnection Layer Poleward of the Cusp

Monday, 15 December 2014: 12:05 PM
Fathima Muzleena Muzamil1, Charles J Farrugia1, Roy B Torbert1, Philip L Pritchett2, Forrest Mozer3, Jack D Scudder4, Christopher T Russell2, Per Even Sandholt5, William F Denig6 and Lynn B Wilson III7, (1)University of New Hampshire Main Campus, Durham, NH, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)University of California Berkeley, Berkeley, CA, United States, (4)Univ of Iowa, Iowa City, IA, United States, (5)University of Oslo, Oslo, Norway, (6)National Geophysical Data Center, Boulder, CO, United States, (7)NASA Goddard Space Flight Center, Greenbelt, MD, United States
We examine several Cluster and Polar crossings of the magnetopause at high latitudes poleward of the cusp under strongly northward interplanetary magnetic field (IMF) in the years 2001-2008. In this effort, we only study crossings under IMFs whose clock angle is less than 45 degrees for a continuous interval of over 2 hours. As shown by several numerical simulations, theoretical analyses, and a few in-situ observations during recent years, asymmetries in plasma density, magnetic field and flow give rise to major features which are significantly different from those observed in a collisionless diffusion region/reconnection layer when conditions are symmetric. Our study of this specific region, i.e. poleward of the cusp, contains examples of a wide dynamic range of values of these physical parameters. Specifically, we focus on counter-streaming flows and the effects of density asymmetries, ranging up to 2 orders of magnitude and a wide spectrum of guide field values on the structure of the diffusion region.