High Latitude Ionospheric Electrodynamics During STEVE and Non-STEVE Substorm Events Journal Article uri icon

Overview

abstract

  • Previous studies have shown that Strong Thermal Emission Velocity; Enhancement (STEVE) events occur at the end of a prolonged substorm; expansion phase. However, the connection between STEVE occurrence and; substorms and the global high-latitude ionospheric electrodynamics; associated with the development of STEVE and non-STEVE substorms are not; yet well understood. The focus of this paper is to identify; electrodynamics features that are unique to STEVE events through a; comprehensive analysis of ionospheric convection patterns estimated from; SuperDARN plasma drift and ground-based magnetometer data using the; Assimilative Mapping of Geospace Observations (AMGeO) procedure. Results; from AMGeO are further analyzed using principal component analysis and; superposed epoch analysis for 32 STEVE and 32 non-STEVE substorm events.; The analysis shows that the magnitude of cross-polar cap potential drop; is generally greater for STEVE events. In contrast to non-STEVE; substorms, the majority of STEVE events investigated accompany with a; pronounced extension of the dawn cell into the pre-midnight subauroral; latitudes, reminiscent of the Harang reversal convection feature where; the eastward electrojet overlaps with the westward electrojet, which; tends to prolong over substorm expansion and recovery phases. This is; consistent with the presence of an enhanced subauroral electric field; confirmed by previous STEVE studies. The global and localized features; of high-latitude ionospheric convection associated with optical STEVE; events characterized in this paper provide important insights into; cross-scale magnetosphere-ionosphere coupling mechanisms that; differentiate STEVE events from non-STEVE substorm events.

publication date

  • March 6, 2022

has restriction

  • hybrid

Date in CU Experts

  • March 15, 2022 8:31 AM

Full Author List

  • Svaldi VC; Matsuo T; Kilcommons L; Gallardo-Lacourt B

author count

  • 4

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