几种特殊地形对气流运动影响的解析研究
投稿时间: 2018-01-14  最后修改时间: 2018-03-29  点此下载全文
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作者单位E-mail
王宇 国防科技大学气象海洋学院 wangyu20140901@163.com 
黄思训 国防科技大学气象海洋学院 huangsxp@163.com 
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:本文在地形相关函数与地形高度函数近似相等的假设下,利用一种解析方法得到多种典型地形影响下的大气中尺度运动的定常解析解以及对应的气流的运动情况。结果表明,在地形上风方的水平方向不呈现波动形态;低(浅)的地形不会在大气中形成急流和转子。对各种有一定高(深)度的地形,当Froude数Fr>1/pi时,大气波动仅出现在地形附近,低层流线接近地形,向上则波动有所减弱;当1/pi>Fr>1/(2pi)时,该波动不仅出现在地形附近,还出现在地形的下风方,波长与地形的水平尺度无关,仅取决于背景场,且向上波动仍有所减弱;当Fr<1/(2pi)时,在地形下风方的大气中层,会形成一支急流,再往下风方,该急流又分为两支,一支位于大气高层,一支位于大气低层,并又会在大气中层再度汇合;在该急流的一侧或两侧,会出现转子。在奇异值Fr=1/(npi)上出现间断,扰动会出现一个急剧增强的现象。
中文关键词:地形,中尺度,解析解,急流,转子
 
Analytical study of the influence of several special topography on the airflow movement
Abstract:On the assumption that the topographic correlation function is approximately equal to the terrain height function, the constant analytical solutions of the mesoscale motion under the influence of some typical terrains are obtained by using an analytical method and the movement of airflow is discussed correspondingly in this paper. The main conclusions are as follows: the airflow does not present any fluctuation on the windward side of the terrain, and jet streams and rotors cannot form in the lower terrain. For the terrains with a certain height (depth), when the Froude number Fr>1/pi, the atmospheric fluctuation only occurs near the terrain, the low-level streamlines are close to the terrain, and the strength of fluctuation decreases with the increase of the height; when 1/pi>Fr>1/(2pi), the fluctuation occurs not only near the terrain, but also on its leeward side. The wave length depends only on the background field, rather than the horizontal scale of the terrain, and the fluctuation decreases gradually with the increase of the height; when Fr<1/(2pi), a jet stream forms in the middle atmosphere of the leeward side of terrain, then it divides into two branches, one locates in the upper atmosphere and the other locates in the lower atmosphere, and they finally converge in the middle atmosphere; rotors appear on one or both sides of the jet stream.There is a sharp increase in the disturbance due to a discontinuity in the singular value Fr=1/(npi).
keywords:topography  mesoscale  analytical solution  jet stream  rotor
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