中文摘要：

利用CODE根据IGS观测站的GPS资料解算的全球电离层 TEC资料，分析了2008年5月12日的中国汶川8．0级地震和2011年3月11日的日本9．0级地震，得到震中区域的电离层TEC时间序列，以27天为背景值用滑动四分位法分析电离层异常，在考虑太阳及地磁活动的因素下，分析结果发现汶川地震和日本地震震前3天震中区域均有明显的正异常。研究表明：两次地震震中附近区域电离层均有明显异常，两次异常峰值点都不在震中正上方，而是位于震中靠近赤道方向，同时在赤道共轭区也存在异常，但是日本地震前异常区域范围和幅度明显大于汶川地震，这表明震前电离层异常扰动确实存在，且异常幅度和地震强度有关。

英文摘要：

To investigate the coupling relationship between earthquake and ionosphere,we process the global TEC data which are estimated from the GPS data of IGS stations by CODE and analyze pre-sersmic ionospheric TEC anomalies of Wenchuan earthquake on May 12th 2008 and Japan earthquake on March 11th 2011.The time series of the ionosphere total electron con-tent over the epicenter are captured,to detect abnormal signal of TEC variation,a sliding quar-tile-based（before 27 days）process is performed.By considering the sun （F10.7 index）and ge-omagnetism activity level（Dst index and Kp index）,the results show a positive disturbance in epicenter region in 3 days before two earthquakes.The global disturbance maps are analyzed and represent that the anomaly peaks before two earthquakes aren’t coincide with the vertical proj ection of the epicenter,but was instead to its south.Corresponding ionospheric anomalies are also observed in the magnetically conj ugated region,but the region and amplitude of anom-aly before Japan earthquake is larger than the anomaly before Wenchuan earthquake .The re-sults show that TEC anomaly before earthquake is really existed and it’s amplitude is connect-ed with earthquake magnitude.