期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
卷 120, 期 6, 页码 5062-5075出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2015JA020986
关键词
tsunami; atmospheric gravity waves; traveling ionospheric disturbances; total electron content; numerical simulations; lower thermospheric response
资金
- National Natural Science Foundation of China [40874100, 41174128]
- U.S. NSF [AGS-1001074]
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1001074] Funding Source: National Science Foundation
Previous GPS observations have revealed that while ionospheric TIDs were seen propagating in all directions away from the 2011 Tohoku earthquake epicenter, the total electron content (TEC) fluctuations associated with the subsequent tsunami were largest for waves propagating toward the northwest of the epicenter. Ionospheric motions observed approximately 10min after the earthquake were attributed to fast acoustic waves directly produced by the earthquake. Waves that first appeared about 40min after the tsunami onset in TEC measurements were attributed to atmospheric gravity waves. In this paper, we conjecture that the remarkably different responses observed for the eastward and westward propagating waves noted in previous observations can be explained by the different ocean depths associated with the two directions of travel and by the effects of the mean winds. The former has consequences for the generated gravity waves (wave spectrum), while their combination has consequences for the ability of the waves to propagate to higher altitudes. Because the ocean depth to the east of the epicenter is greater than that to the west, the eastward propagating tsunami travels faster than the westward propagating tsunami; and hence, the eastward propagating gravity waves that are generated will be faster than the westward waves. We demonstrate that the faster eastward waves encounter regions of evanescence that inhibits their upward propagation, with the result that the westward propagating waves reach the lower thermosphere sooner and with much larger amplitudes than those of the eastward propagating waves. However, at much higher altitudes the slower westward propagating waves are severely damped by viscosity, with the result that only the eastward propagating waves survive to F region altitudes. These results are clearly seen in our full-wave model simulations and also in the evolution of the wave momentum flux calculated using our 2-D, time-dependent model.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据