基于COSMIC掩星数据探测汶川M_S8.0地震震前电离层异常  

Ionosphere anomaly before the Wenchuan M_S8.0 earthquake detected by COSMIC occultation data

作　　者：马新欣[1] 林湛[2] 陈化然[1] 金红林[2] 李大虎[3] 焦立果[1] 刘晓灿[1] 

机构地区：[1]中国地震局地球物理研究所,中国北京100081 [2]中国地震局地震预测研究所,中国北京100036 [3]四川省地震局工程地震研究院,中国成都610041

出　　处：《地震学报》2013年第6期848-855,938,共8页Acta Seismologica Sinica

基　　金：地震行业专项"山基塔基掩星和三频信标综合观测试验"(201108004);基本科研业务经费"基于B样条函数建立电离层电子密度分布模型"(DQJB10B26)项目联合资助

摘　　要：获取COSMIC掩星2级数据,基于球谐函数使用最小二乘拟合法计算模型值,为2008年5月12日汶川MS8.0地震前电离层电子密度变化提供背景依据.同时应用主成分分析法研究最大电子密度,得到各主成分所占能量百分比随时间的变化.研究结果发现,震前在震中邻近区域出现电离层扰动增强现象,且随高度不同存在一定差异,主要集中在F2层300—450km.主成分分析结果显示,4月15日—29日19:00—24:00(地方时)第三主成分能量百分比显著增加.上述结果表明,震前电离层存在异常扰动现象.这一研究结果有助于加强地震电离层耦合机理方面的研究.By a least-squares fitting method we calculated the coefficients of spherical harmonic functions, and examined electron density in and around epi- central region of the Wenchuan Ms8.0 earthquake based on COSMIC occultation data. At the same time we evaluated the maximum electron density using the principal component analysis, and deduced the temporal variation of the contri- bution of each principal component. It was found that the enhanced anomalous TEC disturbances over seismogenic zone took place before the Wenchuan earth- quake in the layer from altitude of 300 km to 450 kin, further more the disturb- ance changed with height. The third principal component increased significantly during 19：00--24：00 （local time） within 13--27 days （from April 15 to 29） pri- or to the Wenchuan earthquake. The results showed that there was a clear iono- spheric anomaly before the Wenchuan earthquake. Result of this study helps us in understanding the seismic-ionospheric coupling model.

关 键 词：COSMIC 球谐函数 最小二乘拟合法 电离层扰动 

分 类 号：P315.722[天文地球—地震学]