华北两次副高边缘暴雨过程卫星云图释用

Analysis and Explanation of Satellite Cloud Images for Two Rainstorm Processes around Edge of Subtropical High in North China

利用实况探空资料与FY-2C、2E卫星探测资料,对2005年8月16日、2010年8月20—21日两次西太副高与西风槽共同作用下出现的华北暴雨过程进行分析,将两次过程卫星云图与各种物理要素场的配置进行对比,得到以下结果。两次过程云系均表现为典型的锋面云系特征,靠近冷空气一侧云带边界光滑整齐。从结构上看,锋面云带主要由多层云系组成。整个云系位于高空槽前580dagpm线与副高外围588dagpm线之间;降水云带由对流云团、稳定性降水云带及混合性降水云带3部分组成,对流云团集中发展在云带靠近副高边缘晴空区一侧,通常位于在584dagpm线与588dagpm线之间靠近副高一侧;稳定性降水集中高空槽前,即云带后部,580dagpm线与584dagpm线之间;混合性降水位于两个云系之间,多产生于584dagpm线附近。云系的分布与各层的垂直速度场、涡度场、散度场,以及中高层的涡度平流场有很好的对应关系。比湿通量、比湿通量散度与假相当位温等温湿参量的分布特征,清楚的解释了锋面云带的移动、发展和分布特征。

Using radiosonde and FY 2E Satellite data, a quantitative analysis of satellite cloud images and physical fields is conducted on two rainstorm processes induced by the subtropical high and westerly trough in August 2005 and August 2010. It is found that there was a continuous complete cloud band at the east of the trough line at 500 hPa and near the boundary of the cold air side, the cloud band was smooth and neat. The cloud system was a typical frontal cloud system, and from a structural point of view, the frontal cloud band was mainly composed by the multi layer cloud systems. The entire cloud band was located between line 580 and line 588, which was composed of convective clouds, a stable precipitation cloud band and mixed precipitation cloud band. The convective clouds were concentrated near the clear zone at the edge of the subtropical high, usually located close to the subtropical high between line 584 and line 588. The stable precipitation was concentrated on the back of the cloud band between line 580 and line 584; the mixed precipitation occurred in the vicinity of the line 584 between two cloud systems. The distribution of the cloud system had a very good correspondence with the vertical velocity field, vorticity field, divergence field, and high level vorticity advection field. The distribution characteristics of temperature and humidity parameters, such as humidity flux, humidity flux divergence, and pseudo equivalent potential temperature, gave a clear explanation of the movement, development, and distribution characteristics of the frontal cloud bands.