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利用GPS-TEC和厦门电离层测高仪数据,分析了汶川大地震前我国地区电离层的形态和变化.其中,利用JPL提供的电离层TEC地图数据分析发现,在地震前3天的下午16~18LT,汶川以东南约20°范围内的我国地区电离层TEC出现了10~15TECU的显著增强,同时在南半球磁力线共轭区也出现了电离层TEC增强现象,增强幅度约10TECU,在此区域外全球其他地区未见明显TEC增加或减少.从TEC数据中也可以看出在地震前6天(5月6日)我国南方地区发生了电离层TEC减小现象,与9日出现的电离层TEC增强现象相比,此次减小的幅度较小(约4TECU)、区域较大(经度方向约80°),在南半球磁力线共轭区域未见如此大面积的TEC同步减小现象.主要分析厦门站数据并参照少数其他台站测高仪资料的监测结果显示,我国多个电离层垂测站均观测到电离层的异常扰动.发现震前3天地震附近地区出现了电离层参量异常增加,与以往研究发现的震前电离层参量异常减小的结果不一致,初步分析此次震前震前3天电离层参量异常增加可能与该区域电场突然增加有关,可能是本次地震的电离层前兆;震前6天电离层参量的异常减小可能与发生在5月5日的地磁小扰动有关,具体因素需进一步分析.
Using the data of GPS-TEC and ionosphere altimeter in Xiamen, the morphology and changes of the ionosphere in China before the Wenchuan Earthquake were analyzed.Using the ionospheric TEC map data provided by JPL, it was found that at 16 o’clock in the afternoon before the earthquake ~ 18LT, the tectonic TEC in China in the region of about 20 ° southeast of Wenchuan has been significantly enhanced by 10 ~ 15 TECU, and the enhancement of ionospheric TEC also appears in the conjugate region of the magnetic line in the southern hemisphere, with an enhancement of about 10 TECU. In this region There is no obvious increase or decrease of TEC in the rest of the world except for the fact that the decrease of ionospheric TEC occurs in the southern part of China 6 days before the earthquake (May 6) Compared with the TEC enhancement phenomenon, the decrease is smaller (about 4 TECU) and the area is larger (about 80 ° in the longitude direction), so there is no such large area TEC synchronization reduction in the conjugate region of the magnetic line in the southern hemisphere. According to the monitoring results of Xiamen station data and a few other altimeter data, abnormal ionospheric disturbances were observed in many vertical ionospheric stations in China, and the anomalous increase of ionospheric parameters appeared in the vicinity of the 3 days before the earthquake ,versus The results of previous studies show that the anomalies in ionospheric parameters before the earthquake decrease are inconsistent. A preliminary analysis of the anomalous increase of ionospheric parameters 3 days before the earthquake may be related to the sudden increase of the electric field in this region, which may be the ionospheric precursors of this earthquake. The anomalous decrease of ionospheric parameters in the first 6 days may be related to the small perturbation of geomagnetic that occurred on May 5, and the specific factors need further analysis.