辨明大洋海啸于中性粘滞大气层的扰动响应分析

发布时间：2018-12-14 12:32

【摘要】：海啸在长距离的传播过程中,与其所诱发的大气重力波的波阵面特征前后连贯一致。同时大气重力波在向上传播过程中,其振幅随高度呈指数性增长,因此在高层大气中提高了其被探测的可能性。本文选取2011年日本海啸及2004年苏门答腊海啸作为中纬度与低纬度的研究事件,建立各自的海啸波模型,并通过全波模型及二维非线性时变模型对此进行数值模拟,进而分析海啸所诱发的不同特性波在粘滞、且含风场的中性大气层中的扰动响应。本文的研究可为今后在大气电离层中探测到此类重力波提供必要的支持,也可为远洋海啸的离岸探测开辟新的应用途径。由于海啸所诱发的大气重力波对电离层E区及以下高度的大气层扰动响应受磁场影响较小,因此电离层E区的扰动情况在一定程度上能够反映海啸波动。本文通过对比分析不同特性的重力波对大气层的扰动响应,发现日本海啸的模拟结果能够很好地解释所观测到的TIDs在震中西北方向出现的强烈扰动现象。模拟进一步发现在海啸发生后约50min,西北向传播的重力波对大气层产生的最快响应应该作用于E区电离层,F区电离层的扰动响应应该以东南向传播的快波为主。而位于低纬度的苏门答腊海啸,其震源朝N250°E方向传播的重力波对低热层大气的扰动响应较大。在高热层大气中,朝N340°E方向传播的重力波的粘滞耗散较小,相比较于向N250°E传播的重力波,更易于在F区电离层上观测到。以上模拟结果的前提是将整个大气层视为中性状态,不考虑大气分子的电离情况。大气重力波对F区电离层的扰动响应由于受到地磁场的作用,应具有纬度相关性。因此未来需要充分考虑中性粒子与电离层离子间的化学反应及动力耦合过程,并通过电离层耦合模型进一步研究大气重力波对电离层的扰动响应,进而针对性的研究纬度相关性是很有必要的。
[Abstract]:During the long distance propagation of tsunami, it is consistent with the wave front characteristics of atmospheric gravity wave induced by tsunami. At the same time, the amplitude of atmospheric gravity wave increases exponentially with the height during its upward propagation, so the probability of its detection is improved in the upper atmosphere. In this paper, the Japanese tsunami of 2011 and the Sumatra tsunami of 2004 are selected as the research events of mid-latitude and low-latitude, and their tsunami wave models are established, and the numerical simulation is carried out through full-wave model and two-dimensional nonlinear time-varying model. Furthermore, the disturbance response of different characteristic waves induced by tsunami in the viscous and wind-contained neutral atmosphere is analyzed. The research in this paper can provide the necessary support for the detection of such gravity waves in the atmospheric ionosphere in the future, and also open a new way for offshore exploration of ocean-going tsunamis. Because the atmospheric gravity wave induced by the tsunami is less affected by the magnetic field to the atmospheric disturbance in the ionospheric E region and below, the disturbance in the ionospheric E region can reflect the tsunami wave to a certain extent. By comparing and analyzing the response of gravity waves with different characteristics to the atmospheric disturbance, it is found that the simulated results of the Japanese tsunami can explain the strong disturbance phenomenon observed in the northwestern direction of the epicenter of the Japanese tsunami. It is further found that, about 50 minutes after the tsunami, the fastest response of the gravity wave propagating in the northwest direction to the atmosphere should act on the ionosphere in region E, and the disturbance response of the ionosphere in region F should be dominated by the fast wave propagating in the southeast direction. However, the gravity waves propagating towards N 250 掳E in the Sumatra tsunami at low latitudes are more responsive to the disturbances in the lower thermosphere atmosphere. In the atmosphere of high thermosphere, the viscosity dissipation of gravity wave propagating towards N340 掳E is smaller, which is more easily observed in the ionosphere of F region than the gravity wave propagating to N250 掳E. The premise of the above simulation is that the whole atmosphere is regarded as a neutral state, and the ionization of atmospheric molecules is not considered. The response of atmospheric gravity wave to the ionospheric disturbance in region F should be latitude dependent due to the effect of geomagnetic field. Therefore, the chemical reaction and dynamic coupling between neutral particles and ionospheric ions should be fully considered in the future, and the response of atmospheric gravity waves to ionospheric disturbances should be further studied by the ionospheric coupling model. It is necessary to study the correlation of latitude.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P352;P731.25

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