11:00 〜 11:15
[PEM14-08] Global Electric Field Response to the Development of High-Latitude Currents During Substorms
キーワード：サブストーム中のFAC発達、サブストーム中の電離層電場応答、Ampere衛星観測、地上磁場・電場観測
This study investigates the spatiotemporal evolution of high-latitude current systems during substorms using AMPERE and compares their characteristics with electric field responses in the mid- and equatorial latitudes on both the dayside and nightside.
There are two primary current systems in the polar ionosphere: Region 1 (R1) currents, linked to the magnetospheric convection, and Region 2 (R2) currents, linked to pressure gradient in the inner magnetosphere. When a substorm occurs due to plasma injection, plasma vortices at the edge of the plasma flow generate the substorm current wedge (SCW), which has the same current polarity as the R1 system. Previous studies have suggested that during the development and decline of these currents, R1 currents enhance the dawn-to-dusk penetration electric field, while R2 currents contribute to the dusk-to-dawn shielding effects, at the mid-, low- and equatorial latitudes. Additionally, the SCW also affects ionospheric currents on the dayside. However, the temporal and spatial evolution of these current systems during substorms and their effects on electric field responses at mid-latitudes and equatorial latitudes remain a controversial issue.
This study aims to elucidate the mechanisms driving electric field responses during substorms by examining the evolution of R1 and R2 currents, as well as the SCW, using AMPERE data. To achieve this, we investigate the temporal and spatial evolution of these currents and compare them with electric field responses in the mid- and equatorial ionosphere. As a case study, we focus on an isolated substorm that occurred at 15:03 UT on April 24, 2011.
Our analysis reveals that electric field responses on the dayside and nightside occur at different times, and the timing of each response corresponds to the development of high-latitude currents observed by AMPERE in their respective sectors. These results suggest that the observed electric fields in the dayside and nightside during substorms are driven by different current sources.
There are two primary current systems in the polar ionosphere: Region 1 (R1) currents, linked to the magnetospheric convection, and Region 2 (R2) currents, linked to pressure gradient in the inner magnetosphere. When a substorm occurs due to plasma injection, plasma vortices at the edge of the plasma flow generate the substorm current wedge (SCW), which has the same current polarity as the R1 system. Previous studies have suggested that during the development and decline of these currents, R1 currents enhance the dawn-to-dusk penetration electric field, while R2 currents contribute to the dusk-to-dawn shielding effects, at the mid-, low- and equatorial latitudes. Additionally, the SCW also affects ionospheric currents on the dayside. However, the temporal and spatial evolution of these current systems during substorms and their effects on electric field responses at mid-latitudes and equatorial latitudes remain a controversial issue.
This study aims to elucidate the mechanisms driving electric field responses during substorms by examining the evolution of R1 and R2 currents, as well as the SCW, using AMPERE data. To achieve this, we investigate the temporal and spatial evolution of these currents and compare them with electric field responses in the mid- and equatorial ionosphere. As a case study, we focus on an isolated substorm that occurred at 15:03 UT on April 24, 2011.
Our analysis reveals that electric field responses on the dayside and nightside occur at different times, and the timing of each response corresponds to the development of high-latitude currents observed by AMPERE in their respective sectors. These results suggest that the observed electric fields in the dayside and nightside during substorms are driven by different current sources.