基于双偏振雷达资料对南海弱台风降水微物理结构的分析

有些南海弱台风在登陆广东时,由于路径复杂、移动缓慢,会对广东地区造成较长时间和较大范围的风雨灾害。使用双偏振雷达对2018—2020年登陆广东的南海弱台风分析,发现南海弱台风在登陆前强降水区主要有两个:一个是位于海上的台风中心南侧眼墙的降水区,另外一个是在台风移动方向的右前方,台风螺旋雨带上岸的区域。在眼墙中,Z_H和K_DP的大值区在低层同位相,Z_DR大值区位于偏上风方向,降水粒子在移动的右侧开始激发,移动的右侧至右前侧为浓度较大的小粒子降水,而右侧和右后侧为大粒子降水。而且台风降水粒子在海洋和陆地有明显差异,陆地由于地形摩擦和抬升作用,降水粒子浓度较大,但水汽和能量供应不足,降水粒子直径较小;海面由于水汽和能量供应充足,对流发展较高,主要为大雨滴的对流降水,但降水粒子浓度不及陆地。 

MICROPHYSICAL STRUCTURE OF PRECIPITATION INDUCED BY WEAK TYPHOON FROM THE SOUTH CHINA SEA BASED ON DUAL POLARIZATION RADAR DATA

When some weak typhoons from the South China Sea land in Guangdong, they cause long-term and large-scale wind and rain disasters to the local area due to their complicated paths and slow movement. This paper uses dual polarization radar data to analyze the microphysical structure of precipitation induced by weak typhoons that came from the South China Sea and landed in Guangdong during 2018—2020. It is found that there were two main areas of strong precipitation before the landing of weak typhoons from the South China Sea. One, on the sea and south to the typhoon center, was the precipitation area of the typhoon eye wall and the other, on the right front of the typhoon's moving direction, was located in the region where the spiral rain bands landed. In the eye wall, the large value areas of horizontal reflectivity (ZH) and differential propagation phase shift (KDP) were in the same phase in the lower levels, and the large value areas of differential reflectivity (ZDR) were located in the upwind direction. The precipitation particles started to be excited on the right side of the movement. The large concentration of small precipitation particles was distributed from the right side to the right front of the movement, while large-particle precipitation appeared on the right side and in the rear right region. In addition, typhoon precipitation particles were significantly different when they were over the ocean and the land. Due to terrain friction and uplift, the concentration of precipitation particles over the land was relatively large, but the water vapor and energy supply was insufficient, and the diameter of precipitation particle was small. Nevertheless, the sea surface had sufficient water vapor and energy supply, and the convection height was relatively high. The precipitation over the ocean was mainly composed of convective precipitation of heavy raindrops, but the concentration of precipitation particles was lower than that of land.