中国气象局关键技术发展专项YBGJXM 2018 2017C03035国家自然科学基金项目41575042，中国气象局关键技术发展专项YBGJXM (2018) 1B-06，浙江省科技重大项目2017C03035
1.Zhejiang Meteorological Observatory, Hangzhou 310017;2.Department of Earth Sciences, Zhejiang University, Hangzhou 310027
National Natural Science Foundation of China Grant 41575042;Special Program for Key Technology development of China Meteorological Administration (Grant YBGJXM 2018) 1B-06;Major Science and Technology projects of Zhejiang Province Grant 2017C03035National Natural Science Foundation of China (Grant 41575042), Special Program for Key Technology development of China Meteorological Administration (Grant YBGJXM (2018) 1B-06), Major Science and Technology projects of Zhejiang Province (Grant 2017C03035)
Using 0.5°×0.5° ERA-Interim analysis data from the European Centre for Medium-Range Weather Forecasts, hourly and minutely observational data from Automatic Weather Stations (AWS), Doppler radar and wind profile radar, as well as infrared cloud images from the Fengyun 2G Satellite (FY-2G), we investigated two local torrential rain events in coastal Zhejiang Province caused by two typhoons with similar tracks, Soudelor and Dujuan, 2015. Both rain events were generated after the typhoons had weakened to tropical depression or remnants and travelled far from Zhejiang. It was found that the rain event associated with Soudelor was triggered by long-duration convergence of a strong low-level southeast jet and a south jet as well as topography. Meridional circulation with persistent water vapor transfer by summer monsoon provided a favorable background for the long-lasting life cycle of Soudelor and its precipitation. In contrast, the rain brought about by remnants of Dujuan was produced by a mesoscale inverted trough, comprised of the east-northeast boundary layer flow out of the cold high in the high latitudes and the east-southeast wind in the north quadrant of Dujuan. Zonal circulation, weak steering currents under a powerful western pacific subtropical high, water vapor transport cut off by monsoonal retreat, and vortex entrainment were reasons for the rapid decay of Dujuan and reduced duration of rain compared with Soudelor. There was no external transfer or convective available potential energy (CAPE) conversion to kinetic energy for both rain events. Rotational divergent wind effects and energy transfer between resolvable and unresolvable scale motions, as well as frictional processes in the lower and middle levels, were main-impact factors in the kinetic energy budgets of these two rain events. As a result, convective forcing and heavy rain occurred despite the small CAPE of Dujuan. Diabatic heating associated with condensational latent heat released by local precipitation massively increased the sensible heat energy in the air column, and consequently, potentially promoted meso- and micro-scale vortices and an inverted trough. As a result, the rain events were intensified and sustained.
潘劲松,周玲丽,陆玮,罗玲,翟国庆.两个相似路径台风残余造成局地特大暴雨的成因机制和能量收支对比分析.大气科学,2019,43(6):1399~1412 PAN Jinsong,ZHOU Lingli,LU Wei,LUO Ling,ZHAI Guoqing.