Observations and Simulations of Cold Air Pooling in Valleys
Observations and Simulations of Cold Air Pooling in Valleys
复制标题
山谷冷空气汇集的观测与模拟
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
A. Veal
中科院分区：
文献类型：
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作者：
S. A. Smith;A. Brown;S. Vosper;P. Murkin;A. Veal
2007年1月20日至4月4日期间，在英格兰西南部的A361公路上使用一辆装有仪器的车辆沿着进行了一系列调查，主要是在晴朗的平静夜晚，以观察山谷中冷空气池的形成。使用气象局统一模型（MetUM®）对其中三种情况进行了高分辨率模拟，结果表明，该模型成功再现了观测到的空气温度沿路线变化的许多特征。对观测结果和模拟结果的分析表明，这些中等山谷内的空气冷却是遮蔽的结果，这减少了从高处向下的湍流热通量。经历大程度冷却的山谷是那些完全解耦的山谷，允许山谷内的近地表空气迅速冷却，以响应地表长波辐射冷却。山谷冷却强度的表现与遮蔽机制的理想化模拟中观察到的相似（Voelman和Brown，2008年，边界层气象学127：429-448）。
A series of surveys was carried out with an instrumented vehicle along the A361 in south-west England between 20 January and 4 April 2007, primarily during clear calm nights in order to observe the formation of pools of cold air in valleys. High resolution simulations were performed for three of these cases using the Met Office Unified Model (MetUM®), which was shown to successfully reproduce many of the features of the observed along-route variations in air temperature. Analysis of the observations and the results of the simulations suggest that the cooling of air within these moderate valleys was the result of sheltering, which reduces the turbulent flux of heat down from aloft. Valleys that experience a large degree of cooling are those that become fully decoupled, allowing the near-surface air within the valley to cool rapidly in response to the surface longwave radiative cooling. The behaviour of the valley cooling intensity is shown to be similar to that observed in idealised simulations of the sheltering mechanism (Vosper and Brown, 2008, Boundary-Layer Meteorol 127:429–448).