The movement of Indian monsoon depressions by interaction with image vortices near the Himalayan wall
The movement of Indian monsoon depressions by interaction with image vortices near the Himalayan wall
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DOI：
10.1002/qj.2812
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发表时间：
2016-07-01
影响因子：
8.9
通讯作者：
Parker, Douglas J.
中科院分区：
文献类型：
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作者：
Hunt, Kieran M. R.;Parker, Douglas J.
印度季风低压向西传的一个简单解释是低压涡旋与喜马拉雅墙的相互作用。这种相互作用可以通过将IMD模拟为水平面（850 hPa）中的点涡并调用屏障后面的图像涡来建模。与图像涡相关的螺线管流允许满足喜马拉雅山的边界条件，并导致IMD涡平行于障碍物向西传播。这个简单的模型进行了测试，对所观察到的IMD的传播速度。观测到的传播速度的直方图，由点涡模型预测归一化，平均值为1.08，标准差为0.68。该模型还解释了所观察到的加强流动的喜马拉雅一侧的IMD，这是一个关键的过程，在加强降雨的印度-恒河平原在季风季节。
It is argued that a simple explanation for the westward propagation of Indian monsoon depressions (IMDs) is the interaction of the depression vortex with the Himalayan wall'. This interaction can be modelled by simulating an IMD as a point vortex in a horizontal plane (at 850 hPa) and invoking image vortices behind the barrier. Solenoidal flows associated with the image vortices allow the boundary conditions at the Himalayas to be met, and cause the IMD vortex to propagate parallel to the barrier, toward the west. This simple model is tested against propagation speeds for observed IMDs. The histogram of observed propagation speed, normalised by the point-vortex model prediction, has a mean of 1.08 and standard deviation of 0.68. The model also explains the observed intensification of flow on the Himalayan side of the IMD which is a key process in enhancing rainfall to the Indo-Gangetic Plain in the monsoon season.