摘要
根据NCEP/NCAR再分析资料、常规观测和加密观测资料以及FY-2C TBB资料,对2008年8月28—30日湖北大暴雨过程两个强降水时段的大尺度环流背景和中尺度对流系统进行诊断分析。在此基础上,利用中尺度数值模式WRF的模拟结果对影响大暴雨过程两个强降水时段的中尺度对流系统和其他物理量场深入分析。结果表明:湖北大暴雨过程存在明显的两个降水增强阶段,它们发生与结束的时间近乎一致,并且第二阶段的强降水比第一阶段强度更大;强降水第一阶段是由低涡切变与地面暖湿气流影响造成的,强降水第二阶段是由低涡切变、中低纬短波槽和地面冷空气共同影响造成的。两个强降水时段逐小时降水与云团特征表明,雨团与云团的活动规律一致,其增幅均出现在晚间至凌晨。同时表明,β中尺度对流云团与暴雨过程关系密切;暖切变线自南向北影响第一时段降水增幅,西南涡中伸展出的冷切变线自西至东影响第二时段降水增幅,模式结果证明由冷切变线引起的第二时段降水增幅更大;两个强降水时段雨区上空均有较强的能量,强的水汽通量辐合贯穿整个降水过程;地面降水中心与其上空湿位涡大值中心有较好的对应关系。
Based on the daily NCEP/NCAR reanalysis data, the conventional and intensive observational data, the brightness temperature （ TBB ） from FY-2C, the large-scale circulation background and mesoscale convective system of two heavy rainfall time periods in a torrential rain process on August 28-30,2008 in Hubei province were diag- nosed,and other physical quantities fields influencing this process were also analyzed by WRF model. The results indicate that there are two significantly precipitation enhancement time periods in this process, and both durations from the beginning to the end are same. Precipitation intensity is stronger in the second time period than in the first one. The first heavy rainfall time period is formed by low vortex shear and surface warm moist airflow, while the second one is caused by low vortex shear, the middle and low level short wave trough and cold surface air. The hourly rainfall and cloud mass characteristics during the two time periods suggest that motions of the rain mass and cloud mass are same, and enhancements of precipitation intensity appear at the night and early morning. It also sug- gests that the ~ mesoscale convective cloud cluster has a close relationship with the torrential rain process. The movement of warm shear line from south to north affects the rainfall enhancement in the first time period, while that of cold shear line of southwest vortex from west to east affects the rainfall enhancement in the second one. Ac- cording to the model results, the increasing amplitude of rainfall in the second time period is more significant. There is strong energy for two heavy rainfall time periods over the study area. There exists the strong water vapor convergence in the whole process. The rainfall center at the surface has a good correlation with a large value center of the moist potential vorticity at upper level.
出处
《气象与环境学报》
2013年第4期1-10,共10页
Journal of Meteorology and Environment
基金
国家自然科学基金(40930951
41075038
40975025
41105073)
公益性(气象)行业科研专项(GYHY201106003)共同资助
关键词
暴雨
强降水
云团
Torrential rain
Heavy rainfall
Cloud mass
