应用改进的图像信息方法,结合DEMETER电磁卫星的电子温度数据,对2008年汶川MS8.0地震进行了长时程的回溯性预测研究.与以往的地震电离层演化图像提取异常的研究相比,将其回溯的时程延长至震前近11个月,并向震后延长48 d.在长期连续的异常扰动演化图中,出现了两个明显的异常时段,且在震前2个月短期内异常扰动明显减弱并趋于背景值.两个时段出现的异常扰动分布位置及其形态以及持续时间皆不重复,这体现了前兆异常的不易确定,难以定性及定量识别的特点.电离层异常扰动特征的长时程研究,有评估其预测参数和模型可靠性的实际作用,也为应用中国卫星观测数据服务于地震预报等研究积累经验,具有借鉴意义.%In this paper, modified PI method was applied to analyze ionospheric anomalous disturbances of Wenchuan MS8.0 earthquake with the data from France DEMETER electromagnetic satellite (electron temperature) for retrospective forecast research. Abnormal pattern evolution characteristics of the Wenchuan M8.0 earthquake was carried out. Compared with previous research about extracting seismo-ionospheric abmormal disturbance, the retrospective timescale was extended to nearly 11 months before the earthquake and 48 days after the earthquake. In the long-term continuous evolution patterns, there were two periods of obvious abnormal disturbance. And in the short term before the impending earthquake, abnormal disturbance significantly reduced and tended towards the background. The location, shape and duration of the abnormal disturbances in the two periods were not repeated, which reflects the uncertainty of the precursory anomaly and the difficulty of qualitative analysis and quantitative identification. The long timescale research of precursor anomalous disturbance characteristics of ionosphere in this paper has practical function for evaluating its forecast parameters and model reliability. It could be used to accumulate experience for the application of the satellite data and forecast earthquake.
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