摘要
利用常规气象观测资料、NCEP再分析资料、卫星和雷达资料,对2013年7月1—2日辽宁地区一次大暴雨过程,从大暴雨发生区附近低空急流、干侵入活动和卫星云图演变角度进行系统的分析。结果表明:此次大暴雨过程发生前低空急流迅速向低层扩展加强,超低空东南急流迅速加强,为大暴雨发生输送了充足的水汽;对流中层干层加强了暴雨过程的对流性不稳定;湿度梯度锋区形成和维持的重要原因为干冷空气侵入。此次大暴雨形成过程中卫星云图的演变为:暴雨发生前有低湿、高位涡的冷空气向低纬度移动、并不断加强;在雨带维持阶段,强降水区在红外和水汽图像,主要特征有向北、向东北、向东、向东南、向南及向西南疏散的外流丝缕状卷云,同时西北侧不断有小尺度的暗区补充;强降水结束前,从南亚高压脊的北侧动力干带东移,反气旋脊快速扩大,反气旋结构更加松散,强降水区附近副热带西风急流逐渐减弱消失;同时可知强降水发生在强对流云团梯度最大值时段,因此卫星云图特征对强降水发生过程有较好的指示意义。此次辽宁地区大暴雨过程两个强降水中心位于背风坡附近,说明地形抬升对此次对流性强降水的对流加强起一定的推动作用。
Based on conventional observation data, reanalysis data and satellite radar data, a torrential rain process in Liaoning province on July 1 to 2,2013 was analyzed. This includes lower jet near the torrential rain area,dry in- vasion and evolution of satellite cloud image. The results show that lower jet extends and strengthens rapidly to the low level before the process, so is super low southeast jet that provides abundant water vapor for the process. Dry layer of convective layer makes convection unstable. Invasion of dry and cold air is an important reason for develo- ping and maintaining humidity gradient in the front area. This process can also be identified from the characteristics of satellite images. Cold air with low humidity and high potential vorticity moves from high latitudes to low lati- tudes, and is continuously strengthened before the rainfall. During the malntainence of precipitation, cloud images are characterized as silk thread-like cirrus outflow, there is no small-scale dry band accompanied with high wind speed eastward from the north side of South Asia high pressure before the end of the heavy rainfall, while there are small-scale dark areas at the northwest side. As strong rain band from rising warm air occupies the upper tropo- sphere anticyclones ridge, the rapid expansion of the anticyclones ridge structure becomes loose. It can be inferred that features of satellite image could be a very good indicator for heavy rainfall forecast, having two strong rainfall centers located in the leeward slope. A heavy rainfall might occur in the maximum period of strong convective cloud gradient, it means that the corresponding terrain plays an important role in promoting the strengthening of strong convective precipitation.
出处
《气象与环境学报》
2015年第6期51-58,共8页
Journal of Meteorology and Environment
基金
中国气象局预报员专项(CMAYBY2014-012)
国家重点基础研究计划(973项目)(2012CB957800)
国家重点基础研究计划973项目(2013CB430103)
灾害天气国家重点实验室开放课题(2012LASW-B8)共同资助
关键词
大暴雨
干侵入
云图演变
地形影响
：Torrential rain
Dry invasion
Cloud evolution
Topographic effect
