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Solar cycle, seasonal, and diurnal variations of subauroral ion drifts: Statistical results
Author(s) -
He Fei,
Zhang XiaoXin,
Chen Bo
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja019807
Subject(s) - solstice , latitude , atmospheric sciences , environmental science , morning , diurnal temperature variation , local time , climatology , solar cycle , precipitation , noon , electron precipitation , meteorology , geology , physics , magnetosphere , plasma , geodesy , mathematics , solar wind , astronomy , statistics , quantum mechanics
The solar cycle, seasonal, and diurnal variations of the subauroral ion drifts (SAIDs) are investigated for the first time to use such a large database of 18,226 SAID events observed by the DMSP satellites during 1987–2012. Statistical results show that SAIDs occur mostly at 60.1° invariant latitude and 2230 magnetic local time with a typical half width of 0.57°, move equatorward during high solar activities with large widths, and have two occurrence peaks in spring and fall equinoxes and two valleys in summer and winter solstices. The seasonal variation of SAID latitude has two valleys in spring and fall, and SAID width has a valley distribution with a minimum in summer. SAIDs exhibit a clear day‐to‐night difference in latitude. The diurnal variation of SAID width has a morning valley and an afternoon peak. The generation mechanism of SAID associated with the electron precipitation and the downward field‐aligned current is also supported in this study.