a-sigma geomagnetic index
收藏DataCite Commons2025-08-25 更新2026-04-25 收录
下载链接：
https://isgi.unistra.fr/doi/index_a-sigma.php
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资源简介：
Purpose of a-sigma index is to provide a characterization of local geomagnetic activity in 4 longitudes sectors and possible hemispheric discrepancies. Based on the am network, in each MLT sector, the K scaled for each station, are averaged, and the result is converted into amplitude using mid-class amplitudes for (K=9 lower limit) = 500 nT.
4 indices are thus calculated: a-sigmaDawn (03–09 MLT), a-sigmaNoon (09–15 MLT), a-sigmaDusk (15–21 MLT), and a-sigmaMidnight (21–03 MLT).
提供机构：
EOST
创建时间：
2025-08-22
