ICS-13 Abstract View


Dynamics of the Sub-Auroral Polarization Streams during geomagnetic disturbances and their relations with energetic particle injection
Zihan, Z.W., wzihan@umich.edu (1)
Shasha, S.Z., shashaz@umich.edu (1)
Sub-Auroral Polarization Streams (SAPS) refer to regions with intense radial electric fields in the inner magnetosphere and poleward electric fields in the conjugate subauroral ionosphere. These large electric fields lead to westward convection flows and sometimes decrease the electron density in the ionosphere. SAPS are important in the magnetosphere-ionosphere-thermosphere coupling process. However, their evolution during geomagnetic disturbances, especially their relationship with energetic particle injections are still not well understood. In this study, we report a conjugate observation of SAPS from the Van Allen Probes (VAP) and the Defense Meteorological Satellite Program (DMSP) on May 18, 2013. In this case, VAP observed large SAPS electric field (~10mV/m) pointing radially outward at the plasmapause. At the same time, a dispersionless energetic particle injection was also observed. However, the magnetic field variations were not consistent with those associated with standard dipolarization fronts. Instead, two pairs of bipolar magnetic field perturbations in the X, Y and Z direction in GSE coordinate near the plasmapause were observed. This signature could be generated by two pairs of field-aligned currents (FACs) with large amplitude. We discuss possible physical connections between the energetic particle injection, the formation of SAPS and field-aligned currents.
(1) Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, 2455 Hayward St.