Study of the ionospheric anomaly before the Wenchuan earthquake

作     者：YU Tao MAO Tian WANG YunGang WANG JingSong 

作者机构：Nation Center for Space Weather China Meteroligical Administration Beijing 100081 China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：2009年第54卷第4期

页      面：1080-1086页

核心收录：

学科分类：070801[理学-固体地球物理学] 070802[理学-空间物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：Supported by National Natural Science Foundation of China (Grant No. 40504023) National High-Tech Research Program of China (Grant No. 500009003) 

主　　题：电离层异常 地震前 汶川 电离层参数 地球电离层 地磁场扰动 华南地区 TEC 

摘      要：The behavior of the ionosphere before the Wenchuan earthquake is analyzed with the global TEC and ionospheric foF2 observed at Xiamen. It can be found from TEC maps that in the afternoon (16―18LT) on May 9, 2008, 3 days before the earthquake, there is an enhancement of TEC with an amplitude of 10―15 TECU appearing in the east-south direction of Wenchuan, and another enhancement appears at the conjugate region of the Southern Hemisphere with an amplitude of 10 TECU, but no obvious in-crement or decrement can be seen in other regions on global scale. It can also be found that on May 6 (6 days before the great earthquake), there is a decrement of TEC with small amplitude of 4TECU and larger area with 80° along the longitude in southern China, and there is no synchronous decrement observed at the conjugate region of the Southern Hemisphere. There are also many anomalies ob-served by ionosondes across China. The result shows that foF2 and TEC abnormally increased, which is different from pervious results that ionospheric parameters decreased prior to earthquakes. Pre-liminary results suggest that the enhancement on May 9 maybe has a close relationship with the pos-sible enhancement of ionospheric electric fields, and it may be an ionospheric precursor of earth-quakes. Whereas the decrement on May 6 may be attributed to the geomagnetic disturbance appearing on May 5.