西南涡对流云中夹卷率的模拟研究
投稿时间: 2016-11-28  最后修改时间: 2017-01-13  点此下载全文
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作者单位E-mail
郭小浩 南京信息工程大学 gxh246226@126.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:本文使用中尺度数值模式WRF(Weather Research and Forecast)模拟了2010年7月8日至9日发生在四川盆地的一次西南涡降水天气过程,并计算了该过程中零度层以下对流云中的夹卷率。从云内垂直特征看:云内的含水量、垂直风速和浮力都在云底之上随高度递增而在云顶附近随高度递减;云内的湿静力能则主要随高度递减;夹卷率在云底以上随高度递减,而在云顶附近随高度递增,但是云顶高度越高则云顶附近的递增趋势越不明显。另外,夹卷率和云内的云水、雨水含量都呈负相关,说明夹卷抑制了对流云的发展以及地面降水。当假设被夹卷的环境空气来自云边界附近时,计算所得的夹卷率值要大于假设夹卷空气远离云边界所得值,但这两种假设中夹卷率的其他特征是类似的。从演变特征看,夹卷率总体上随时间减小,这和这段时间内对流云整体发展增高有关。
中文关键词:夹卷率  西南涡  WRF模拟
 
A Simulation Study of Entrainment Rate in Southwest Vortex Convective clouds
Abstract:In this paper, a southwest vortex rainfall process over Sichuan Basin on 8-9 July 2010 is simulated by Mesoscale Weather Research and Forecasting (WRF) model, and entrainment rate in convective clouds under 0 癈 layer is estimated by simulation results. It is found that liquid water content and vertical velocity in cloud increase with height above cloud base and decrease with height near cloud top. Moisture static energy mainly reduces with height in cloud. Entrainment rate decreases with height above cloud base but increases with height near cloud top. For the clouds the top of them is higher, the increasing intensity of entrainment rate near cloud top is weaker. In addition, entrainment rate is negatively correlated with both cloud water content and rain water content, and this indicates that entrainment suppress the development of convective cloud and precipitation. When we assume the entrained environmental air surrounding the cloud edge, the estimated entrainment rate is larger than the corresponding value when assuming the entrained air is far away from the cloud edge. But some other characteristics about entrainment rate under the two assumptions are similar. Moreover, Entrainment rate decreases with time as a whole and this is related to the development and growing of cloud ensemble during this time.
keywords:entrainment rate  Southwest Vortex  WRF simulation
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