2020年7月两次入海江淮气旋爆发性与非爆发性发展特征对比分析

利用高时空分辨率的欧洲中期天气预报中心（European Centre for Medium-Range Weather Forecasts,ECMWF）对全球气候的第五代大气再分析数据集（European Re-Analyses 5,ERA5）,对比分析了2020年7月淮河上游地区的两次江淮气旋过程,并结合海洋—大气—波浪—泥沙耦合模式（Coupled Ocean-Atmosphere-Wave-Sediment Transport modeling system,COAWST）进行敏感性试验,探讨同一气候尺度背景下,高低频大气环流形势和海气耦合作用对江淮气旋的影响。结果表明,低空环流形势的高频变化和海表温度的升高对气旋的大风影响和强度发展有重要作用。低空环流形势中,存在"气旋—反气旋—气旋"环流天气尺度波列,易造成气旋大风叠加增强;海气交互界面的高海表温度加热作用导致的感热和潜热释放通过气旋北部弯曲锋面强烈的上升运动,为气旋发展提供能量,促进气旋入海后爆发性增强。

Comparing the explosive and non-explosive developing characters of two Jiang-huai cyclones entering the sea in July 2020

Based on the European Re-Analyses 5 (ERA5) from European Centre for Medium-Range Weather Forecasts (ECMWF), evolutions of two Jianghuai cyclones in the upper Huaihe region during July 2020 were compared by using a regional Couple Ocean-Atmosphere-Wave-Sediment Transport modeling system (COAWST). The aim is to examine how the atmospheric circulation of different time scales and ocean-atmosphere interaction affect the evolution of Jianghuai cyclone event, under the same background state. Results show that, the high frequency variation of atmospheric circulation and the enhancement of sea surface temperature play important roles in the development of Jianghuai cyclones. For the atmospheric high frequency circulation, the superposition of low-altitude weather-scale "counter clock wise-clock wise-counter clock wise" wave train enhances the cyclone wind speed. At the ocean-atmosphere interface, warmer sea surface temperature provides heat and water vapor energy for the development of Jianghuai cyclones through the ascending motion in the frontal region. This promotes the rapid enhancement of the cyclones after they enter the ocean.