利用日本GPS网探测2011年Tohoku海啸引发的电离层扰动

海平面的海啸波会产生大气重力波进而引发电离层扰动.本文利用日本GPS总电子含量数据来探测2011年3月11日Tohoku海啸引发的电离层扰动.观测结果表明，在日本上空的电离层中存在两种重力波信号，分别由海平面的海啸波以及地震破裂过程产生.地震产生的电离层重力波分布在震中周围（包括海洋上空以及远离海洋的区域），而海啸引发的电离层重力波主要分布在海洋上空.地震产生的电离层重力波具有不同的水平速度，包括约210 m·s^-1以及170 m·s^-1，其频率为1.5 mHz；而海啸引发的电离层重力波水平速度快于前者，约为280 m·s^-1，其频率为1.0 mHz.此外，海啸引发电离层重力波与海平面上的海啸波有相似的水平速度、方向、运行时间、波形以及频率等传播特征.本文的研究将电离层中的海啸信号与地震信号区分开来，进一步确认电离层对海啸波的敏感性.

Detection of ionospheric disturbances driven by the 2011 Tohoku tsunami using GPS network in Japan

Tsunami waves can produce atmospheric gravity waves and thus perturb the ionosphere. In this study, we use the GPS total electron content data in Japan to detect the ionospheric disturbances triggered by the Tohoku tsunami that occurred on 11 March 2011. The results show that there are two types of gravity waves in the ionosphere over Japan, which is produced by the tsunami waves and the seismic rupture process, respectively. The earthquake-driven ionospheric gravity waves are distributed around the epicenter (including the areas over and far from the ocean) whereas the tsunami-driven ionospheric gravity waves are observed above the ocean. The earthquake-driven ionospheric gravity waves have different horizontal velocities, including about 210 m·s^-1 and 170 m·s^-1, and frequency of about 1.5 mHz. The tsunami-driven ionospheric gravity waves have velocity of about 280 m·s^-1, which are faster than that of the earthquake-driven ionospheric gravity waves, and frequency of about 1.0 mHz. In addition, the tsunami-driven ionospheric gravity waves have similar propagation characteristics to the causative tsunami waves in terms of horizontal velocity, direction, travel time, waveform and frequency.This study distinguishes the tsunami signals in ionosphere from ionospheric disturbances triggered by the earthquake event and confirms again that the ionosphere is sensitive to tsunami waves.