2013年1月
Assessment of the auroral electrojet index performance under various geomagnetic conditions
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
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- 巻
- 92
- 号
- 開始ページ
- 31
- 終了ページ
- 36
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1016/j.jastp.2012.09.017
- 出版者・発行元
- PERGAMON-ELSEVIER SCIENCE LTD
Saturation of the auroral electrojet (AE) index during storm times is a phenomenon that has been known but not fully understood. To address this puzzle, here we correlate the (provisional) AE index with net field-aligned current (Net-dB) index, which is a data product derived with magnetic field measurements from the Iridium satellite constellation (Anderson et al., 2010), with an assumption that AE is largely measuring convection driven by the field-aligned currents represented by the Net-dB index. The Net-dB index has a time resolution of similar to 45 mm and is currently available from February 18, 1999, to May 31, 2008. It is found that, for the entire data period, there is a good linear correlation (r=0.74) between the AE index, when averaging over the Net-dB index time grids, and the Net-dB index, suggesting that statistically similar to 55% of the ionospheric Hall currents correlate with large scale convection as reflected in the field-aligned currents. It is also found that the correlation decreases during storm times, with a clear decreasing trend toward a more negative Sym-H. For large storms (Sym-H < - 100 nT), the correlation becomes weak (r < 0.4). Two correlation peaks are identified: a major peak (r=0.73) occurring at Sym-H > 30 nT and a secondary peak (r=0.66) at Sym-H similar to -50 to -30 nT. A further study shows that the variations of the AE-Net-dB correlation are associated with the location of the field-aligned currents into and out of the ionosphere relative to the ground magnetometer stations, as expected often but not demonstrated in the past. (C) 2012 Elsevier Ltd. All rights reserved.
- リンク情報
- ID情報
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- DOI : 10.1016/j.jastp.2012.09.017
- ISSN : 1364-6826
- J-Global ID : 201302295675935178
- Web of Science ID : WOS:000314624600005