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A subauroral polarization stream driven by field‐aligned currents associated with precipitating energetic ions caused by EMIC waves: A case study
Author(s) -
Yuan Zhigang,
Xiong Ying,
Qiao Zheng,
Li Haimeng,
Huang Shiyong,
Wang Dedong,
Deng Xiaohua,
Raita Tero,
Wang Jingfang
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2015ja021804
Subject(s) - geophysics , magnetosphere , ionosphere , physics , substorm , ring current , ion , polarization (electrochemistry) , computational physics , plasma sheet , atomic physics , plasma , chemistry , nuclear physics , quantum mechanics
During the energetic ion injection event observed by the Los Alamos National Laboratory geosynchronous spacecraft, observations of the NOAA 15 satellite and Finnish network of search coil magnetometers have shown that a sharp enhancement of precipitating ring current (RC) ion flux is contributed to the pitch angle scattering caused by electromagnetic ion cyclotron (EMIC) waves. At subauroral latitudes, lower than the equatorward edge of precipitating electrons from the plasma sheet, the DMSP F13 satellite observed a subauroral polarization stream (SAPS) with a peak velocity of 688 m/s. When passing the region of EMIC waves derived by the Finnish network of search coil magnetometers and NOAA 15 satellite, the DMSP F13 satellite simultaneously observed field‐aligned currents (FACs) flowing into the ionosphere and precipitating RC ions in the region of the SAPS. The peak of the SAPS accords to the minimum of the ion density in the region of the SAPS. Our result suggests that loss of RC ions caused by EMIC waves would possibly lead to FACs flowing into the ionosphere and drive the SAPS in the evening sector.