北京地磁台K指数3小时扰幅修正及K指数自动标定

hina is mostly below geomagnetic latitude 40°and the K-index 3-hour disturbance range is usually defined as 3—6—12—24—40—70—12—200—300(nT). This K-scale is chosen according to a series of laws advised by Bartels and based on the observed value of So-Sè observatory (geomagnetic latitude 20.88°). However, various geomagnetic observa- tories locate at various geomagnetic latitudes and consequently the K-scale needs to be adjusted. We discuss the K-scale of geomagnetic Observatory Beijing as an example in this paper. According to Bartels advice K-scale is mainly chosen by the method of K-index frequency distribution comparison. So we respectively take So-Sè Observatory’s K-index and Kp- index from 1994 to 1999 as criterions and compare the frequency distribution of scaled K-index in Beijing Observatory with that of them and then give a new K-scale as 3.9—7.8—15.6—31.2—47.5—70—120—200—300(nT). On the basis of this new K-scale and modified FMI method we scale the K-index of Beijing in 1997. The frequency distribution comparison between this result and the K-index of Observatory Beijing and So-Sè in the Geomagnetic Storm Fundamental Database and Kp-index and the corresponding differences statistic during the same 3-hour section show that the new K-scale and modified FMI method are better then the old ones.