2019年台风利奇马引发山东特大暴雨成因分析

利用地面观测资料、雷达资料、FY-2G卫星云图资料及欧洲中心细网格资料,对台风利奇马登陆北上引发山东特大暴雨的成因进行分析。发现:利奇马登陆北上过程中,冷空气先后从台风的西部、西南部与南部侵入至台风中心内部,使其暖心结构逐渐减弱,其变性时段发生在10日20:00至11日08:00。山东的特大暴雨主要出现在台风变性前12h至台风变性后6h。变性之前的暴雨主要是由于台风螺旋云带与高空槽尾部云系相叠加造成的,变性之后的暴雨则是由于冷空气侵入致使台风外围云系演变成强对流复合体造成的。变性之前,对流层内800～500hPa风速小,500～250hPa风速大,气层内有暖平流,整层的上升运动,降水以暖区对流降水为主;变性之后800～500hPa风速大,500～250hPa风速小,500hPa至地面是上升运动,以上为下沉运动,降水以斜压锋区附近的对流降水为主。当500hPa至地面气层内出现冷平流时,湿层变薄,降水趋于减弱。特大暴雨区出现在台风中心西北方向,与850hPa假相当位温锋区与水汽通量散度辐合大值区相吻合。

Causual Analysis of Extra Torrential Rain of Typhoon Lekima in Shandong in 2019

Using the surface observation data, radar data, FY 2G satellite cloud images and ECMWF_HR data, the extra torrential rain of Typhoon Lekima in Shandong in 2019 is analyzed. The results show that during the landfalling and northward moving process of Lekima, the cold air invaded into the center from west, southwest and south of the typhoon, which gradually weakened its warm center structure and during the extratropical transition period from 20:00 of 10 August to 08:00 of 11 August. The extra torrential rain in Shandong occurred during the period of 12 hours ahead and 6 hours later of the extratropical transition. Before the transition, the precipitation in Shandong was mainly caused by the interaction between the spiral cloud belt of the typhoon and the tail clouds of the low trough, but the precipitation during the transition was caused by the cold air intrusion which made the clouds outside of the typhoon develop into mesoscale convective convergence. Before the transition, the wind speed of 800 to 500 hPa in the troposphere was small, and that of 500 to 250 hPa was large. There were warm advection and ascending motion in the air layer, and the main precipitation came from convective precipitation in the warm zone. After the transition, the wind speed of 800 to 500 hPa was large, and that of 500 to 250 hPa was small. The ascending motion lain from 500 hPa to the ground, and the descending motion was above 500 hPa. The precipitation belonged mainly the convective precipitation near the barocline front area. When the cold advection appeared between 500 hPa to the ground, the wet layer became thinner and the precipitation tended to weaken. The heavy rain appeared in the energy front on the northwest direction of the typhoon center, which was consistent with the divergence convergence of water vapor flux at 850 hPa.