地磁活动D_(st)指数存在的问题与思考  

Some issues of the geomagnetic D_(st) index and discussion

作　　者：吴迎燕[1] WU YingYan(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地球物理学进展》2022年第4期1512-1519,共8页Progress in Geophysics

基　　金：国家自然科学基金面上项目(42274107);国家重点研发项目(2018YFC1503504-03);中国地震局地震预测研究所基本科研业务费专项(CEAIEF20220207,2021IEF0709);APSCO亚太合作地震研究项目二期与ISSI-BJ项目;国家自然基金青年基金项目(40804043)联合资助。

摘　　要：D_(st)指数是空间物理领域应用最为广泛的地磁活动指数之一.它是用于监测磁暴活动及赤道环电流变化的重要参数.虽然其计算简便,具有连续性和时序性好的优势,但是不可避免伴随一系列问题.本文回顾了几十年来关于D_(st)指数的物理意义和计算方法等问题的认识,并对指数计算中关于台站和暴时变化双重因素对指数可能产生的影响进行分析.结果表明,D_(st)指数具有物理意义复杂、不能完全反映磁暴过程、计算中存在误差以及数学意义不明确等问题.特别是例如长期变所引入的误差,甚至可能对磁暴分级产生影响.此外,在暴时变化地方时不对称和台站分布的空间不均匀的双重因素作用下,D_(st)指数的数学意义并不明确.它既非反映暴时变化均值,也非强度极大值.该问题对于磁暴定量化具有怎样的意义需要未来作进一步探讨.The D_(st) index is one of the most popular geomagnetic activity index,as an key parameter for monitoring the geomagnetic storm and the equatorial ring current.Even with well continuity and long time series,however,it is accompanied with some issues.This paper takes an comprehensive review about the results of predecessors about the physical meaning and calculation technique of the D_(st) index,and meanwhile processes a analyzing about the possible influence from the dual factors of the homogeneous distribution of stations and the asymmetry of the storm-time variations.It shows that,the D_(st) index is born with some issues such as complex physical origins,poor reflection of the geomagnetic storm process,several error terms and unclear mathematical meaning,et al.In particularly,for example,the errors introduced by long-term variation may even impact on the classification of the geomagnetic storm.Under the dual mechanism of the asymmetry of the storm-time variation and the distribution of the stations,in addition,the mathematical meaning of the D_(st) index is ambiguity or undefined,not the mean value nor the maximum value.It should be further discussed in the future.

关 键 词：地磁活动指数 暴时变化 磁层电流体系 台站分布 

分 类 号：P318[天文地球—固体地球物理学] P353[天文地球—地球物理学]