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Numerical simulations of generation and propagation of the traveling atmospheric disturbances in the thermosphere

热层中移动大气扰动的产生和传播的数值模拟

基本信息

批准号：
18540442
负责人：
FUJIWARA Hitoshi
金额：
$ 2.15万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

In addition to the traveling atmospheric disturbances (TADs) generated during geomagnetically disturbed periods, we investigated characteristics of the TADs generated during geomagnetically quiet periods. From numerical simulations with a general circulation model (GCM) which covers all the atmospheric regions (troposphere, stratosphere, mesosphere, and thermosphere), we showed TADS generated at around the solar terminator, midnight temperature maximum, and moving auroral oval during geomagnetically quiet periods [Fujiwara and Miyoshi, 2006]. The results suggest that pressure bulges around these areas can generate TADs during the quiet periods.We also investigated effects of the lower atmosphere on generation and propagation of the TADs. GCM simulations showed that the amplitudes of TADs were largely modulated by the effects from the lower atmosphere, suggesting that variability of TADs was caused by day-to-day variations of the lower atmosphere. The atmospheric gravity waves propagati … More ng from the lower atmosphere should be important as energy and momentum sources in the thermosphere. In order to investigate characteristics of the atmospheric gravity waves in the thermosphere, GCM simulations were performed [Miyoshi and Fujiwara, 20081. The GCM simulations showed that short-period gravity waves were dominant in the thermosphere. The dominant period (zonal phase velocity) of gravity waves decreased (increased) with height.In this research project, we attempted to estimate the electromagnetic energy deposition rate (Joule heating rate) in the polar cap thermosphere from radar observations which were carried out in collaboration with several countries. From the simultaneous observations with the EISCAT Svalbard radar and the CUTLASS Finland radar, we derived the height distributions of the thermospheric heating rate at the F region height in association with electromagnetic energy inputs into the dayside polar cap/cusp region [Fujiwara et al., 2007]. We will investigate energy budget and dynamics in the polar thermosphere/ionosphere from GCM simulations with use of above radar data. Less

除了在地磁扰动期间产生的旅行大气扰动（TADs），我们研究了在地磁平静期间产生的TADs的特性。通过使用覆盖所有大气区域（对流层、平流层、中层和热层）的大气环流模型（GCM）进行的数值模拟，我们发现TADS在太阳终结点附近、午夜温度最高点以及地磁平静期的移动极光椭圆产生[Fujiwara and Miyoshi，2006]。结果表明，在平静期，这些区域周围的气压凸起可以产生TADs，我们还研究了低层大气对TADs产生和传播的影响。GCM模拟结果表明，TADs的振幅在很大程度上受低层大气的影响，表明TADs的变化是由低层大气的逐日变化引起的。大气重力波传播 ...更多信息来自低层大气的天然气作为热层的能量和动量来源应该很重要。为了研究热大气层中大气重力波的特征，进行了GCM模拟[Miyoshi和Fujiwara，20081]。大气环流模式的模拟表明，短周期重力波在热层中占主导地位。重力波的优势周期（纬向相速度）随高度的增加而减小（增加）。在本研究项目中，我们试图通过与几个国家合作进行的雷达观测来估计极帽热层中的电磁能量沉积率（焦耳加热率）。根据EISCAT斯瓦尔巴德雷达和CUTLASS芬兰雷达的同时观测，我们推导出了F区域高度处的热层加热率的高度分布，并与向阳面极冠/尖点区域的电磁能量输入相关联[Fujiwara等人，2007年]。我们将利用上述雷达资料从GCM模拟中研究极地热层/电离层的能量收支和动力学。少