白谱法在电离层扰动研究中的应用

Application of white spectrum method in the study of ionospheric disturbances

将电离层扰动从其背景中分离出来一直是电离层扰动研究的核心与难点。文章综述白谱法在电离层扰动研究方面取得的进展,主要有:1)白谱法比常规电离层扰动提取方法能更好地描述磁暴期间电离层的扰动,利用白谱法构建的电离层天气单站指数Js、全球指数Jp和区域指数Jr与Dst指数之间存在极好的关联性,可以直接利用Dst来对Jp进行预报。2)白谱法同样适合研究强磁暴期间的电离层异常弱响应。对比研究发现,电离层在强磁暴条件下的弱响应不依赖于采用的扰动提取方法本身,并且该现象的出现与纬度、地方时及磁暴前期条件强烈相关。3)白谱法是研究地磁平静期由其他扰动源引起电离层扰动的有力工具。基于白谱法构建的Js分布图能够很好地反映台风过程中电离层扰动的空间特征。

It is a core issue and a difficult point in the study of the ionosphere to extract the ionospheric disturbance from the background.This paper briefly reviews the progress of the spectral whitening method(SWM)in the study of ionospheric disturbances.It is shown that,compared with the traditional ionospheric disturbance extraction method,the SWM is more sensitive to identify the ionospheric disturbance responding to the geomagnetic storm.The ionospheric weather single station index Js,the global index Jp and the regional index Jr constructed by the SWM are closely correlated to the Dst value.This makes it possible to forecast Jp by the Dst;It is also shown that the SWM is also suitable for studying the weak ionospheric response during a severe geomagnetic storm.A comparison indicates that the weak response of the ionosphere under the condition of a strong geomagnetic storm does not depend on the disturbance extraction method itself,which is strongly related to the latitude,the local time and the conditions of the early geomagnetic storm.The SWM may serve as a useful tool to study the ionospheric disturbances responding to other sources during the quiet geomagnetic period.Based on SWM,the Js Map can well reflect the spatial characteristics of the ionospheric disturbance during a typhoon process.