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利用地基GPS观测资料反演的垂直电子总含量(VTEC),本文考察了2008年5月12日汶川M_s8.0地震期间的电离层变化.在考察过程中,以前10天的VTEC均值和伴随的2倍标准偏差作为参考来识别电离层异常.最终的考察分析结果表明:(1)VTEC的异常增加出现在5月3日和5月9日,而VTEC的异常减小出现在4月29日和5月6日;(2)所有这4天的电离层VTEC异常持续时间均超过了4 h,且异常自东向西漂移;(3)相对于电离层的非扰动状态,在5次电离层异常的峰值时刻,震中附近VTEC增加或减小超过30%的空间区域沿经、纬向分别超过了4000 km和1500 km.鉴于地震期间的日一地空间环境和电离层VTEC异常特征,我们认为,5月3日下午和5月9日的VTEC正异常可能是本次汶川地震的电离层前兆.
Using the total vertical electron total content (VTEC) retrieved from the ground-based GPS observations, we examine the ionospheric variations during the Wenchuan M_s8.0 earthquake on May 12, 2008. During the study, the mean VTEC over the previous 10 days and the accompanying 2 times the standard deviation as a reference to identify the ionospheric abnormalities.The final inspection and analysis results show that: (1) VTEC anomaly increases appear on May 3 and May 9, while the abnormal decrease of VTEC appeared on April 29 And May 6; (2) all 4 days of ionospheric VTEC anomalies last longer than 4 h and anomalies drift from east to west; (3) relative to the ionospheric uncontrolled state, At the peak anomalous time of the epicenter, the space area where the VTEC increases or decreases by more than 30% near the epicenter exceeds 4000 km and 1500 km along the latitude and longitude, respectively. In view of the terrestrial-temporal space environment and the ionospheric VTEC anomaly during the earthquake, we It is considered that the positive VTEC anomaly on the afternoon of May 3 and May 9 may be the ionospheric precursors of this Wenchuan earthquake.