New Features of Substorm and Storm Dynamics Revealed by Coordinated ISR-ASI Measurements of Auroral Dynamics

Larry R Lyons1, Yukitoshi Nishimura2, Donald Hampton3, Vassilis Angelopoulos4, Eric Donovan5, Michael J Nicolls6 and Steven Chen6, (1)University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK, United States, (4)University of California Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (5)University of Calgary, Calgary, AB, Canada, (6)SRI International Menlo Park, Menlo Park, CA, United States

Contact First Author: Larry R Lyons; larry@atmos.ucla.edu

Abstract ID#: 34572

 

English Abstract:
Coordinated imager and radar observations of the auroral oval have previously revealed that bursts of enhanced flow within the plasma sheet lead to most magnetosphere-ionosphere disturbances (i.e., PBIs, streamers, substorms). Using incoherent-scatter radar and all-sky-imager observations, we have identified weak, azimuthally moving auroral features near the equatorward boundary of the auroral oval. We find that they are associated with large azimuthal flow bursts in the SAPS region, and we find evidence that they originate from tail flow bursts that are guided to the SAPS by the large-scale evening side convection. We have evidence that some of these flow bursts can extend earthward of the pre-existing SAPS region, leading to ring current earthward injections and proton aurora. We have previously seen that localized flow enhancements from the polar cap can contribute significantly to plasma sheet flow bursts and substorm expansion phase activity. We now have found striking new evidence that these polar cap flow enhancements feed new plasma into the head of the westward traveling surge, and thus may play a critical in driving the surge.
Back to: The Physics of the Aurora I