【摘要】 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.更多还原

【Abstract】 In this paper, we investigated the variations of the ionospheric Vertical Total Electron Content (VTEC) derived from the ground-based GPS observations during the 12 May 2008 M_s8.0 Wenchuan earthquake.A mean of the previous 10-day VTECs and the associated two standard deviations are utilized as a reference for identifying the ionospheric anomalies.The analysis showed that (1) the anomalous enhancements of VTEC appeared on May 3 and 9, while the anomalous decreases appeared on April 29 and May 6;(2)all of the ionospheric anomalies lasted beyond 4 hours and drifted from east to west;(3)relative to a non-perturbed state of the ionosphere, the zones of the VTEC decrease or enhancement by more than 30% around the epicenter had spatial scale of more than 4000 km in longitude and 1500 km in latitude at five peak times of the ionospheric anomalies.In view of the solar-terrestrial environment and the characters of the ionospheric anomalies, we think that the positive anomalies of VTEC in the afternoon of May 3 and on May 9 are probably the ionospheric precursors of Wenchuan earthquake.更多还原