西南涡降水过程中云物理特征的数值模拟研究

论文总字数：19213字

目 录

1 引言………………………………………………………………… 1

2 概况………………………………………………………………… 3

2.1 天气过程概况 ............................................................................................................. 3

2.2 降水云带发展概况 ..................................................................................................... 3

3 模拟方案及结果检验……………………………………………… 3

3.1 模式设计与实验方案 ................................................................................................. 3

3.2 模拟降水量与实况降水量比较................................................................................... 4

4 微物理特征………………………………………………………… 5

4.1 地面降水简介............................................................................................................... 5

4.2 各相态水成物的时间变化特征.....................................................................................5

4.3 各相态水成物的垂直分布特征................................................................................... 6

4.4 水成物源汇项分析....................................................................................................... 7

4.4.1 雨的源汇项分析................................................................................................ 7

4.4.2 云滴的源汇项分析............................................................................................ 8

4.4.3 冰晶的源汇项分析............................................................................................ 9

4.4.4 雪的源汇项分析................................................................................................ 10

4.4.5 霰的源汇项分析................................................................................................ 11

5 结论………………………………………………………………… 12

5.1 主要结论 ...................................................................................................................... 12

5.2 不足与展望 .................................................................................................................. 12

参考文献……………………………………………………………… 12

致谢…………………………………………………………………… 15

西南涡降水过程中云物理特征的数值模拟研究

芮雪

, China

Abstract：A precipitation process occurred from July 8 to July 10, 2010, which was associated with southwest vortex, is selected to get further comprehension of the cloud physical processes. The mesoscale model WRF is used to simulate this precipitation process. The distribution characteristics of the hydrometeors’ number concentration and mix ratio, which includes raindrop, snow, graupel, ice and cloud drop over time and altitude is analyzed in detail. Especially, the source and sink of the hydrometeors in cloud is discussed in detail. The results show that microphysical processes in cloud have a great influence on precipitation characteristics. There are a large number of ice-phase particles such as snow and graupel, which produced by water vapor sublimation and collection of clouds raindrops, in the upper layer of the convective cloud, confirming that the convection in the cloud is very strong. Cloud droplets and raindrops exist in the lower troposphere and raindrops are the main precipitation element. It was found that the occurrence and development of raindrops are mainly owing to the melting of snow and graupel and the collision of cloud water, especially the melting of graupel plays the most significant role in this precipitation, through the observation of each hydrous product’s source and sink.

Key words：Southwest Vortex, precipitation, WRF, Microphysical characteristics

1. 引言

西南低涡是一种闭合气旋式低涡环流，出现在我国西南地区，在川藏地区特殊地形和独特的大气环流条件综合作用下产生。西南涡作为我国一种重要的暴雨天气系统，全年各月都可能出现，主要出现在4月至9月，但是能够引起强对流天气的西南涡一般发生在夏半年 ^[3-4][49]。其水平尺度约为三到五个经距，结构常常为暖性，存在时间大多低于小时^[1-2,5-6]，也会有个别西南涡经过发展后可以存在5天以上。

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