西北东部一次强降水形成机制及能量来源  

Formation mechanism and energy source of a heavy rainfall event in the eastern northwest region

作　　者：石霞 刘维成 陈晓燕 黄玉霞[2] 谭丹[2] 伍继业 SHI Xia;LIU Weicheng;CHEN Xiaoyan;HUANG Yuxia;TAN Dan;WU Jiye(Institute of Arid Meteorology,China Meteorological Administration,Gansu Key Laboratory of Arid Climatic Changeand Reducing Disaster,Key Laboratory of Arid Climatic Change,Lanzhou 730020,Gansu,China;Lanzhou Central Meteorological Observatory,Lanzhou 730020,Gansu,China;Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China)

机构地区：[1]中国气象局兰州干旱气象研究所,甘肃省干旱气候变化与减灾重点实验室,中国气象局干旱气候变化与减灾重点开放实验室,甘肃兰州730020 [2]兰州中心气象台,甘肃兰州730020 [3]南京信息工程大学,江苏南京210044

出　　处：《干旱区研究》2025年第4期600-612,共13页Arid Zone Research

基　　金：甘肃省自然科学基金项目(23JRRA1573,24JRRA1182);中国气象局气象能力提升联合研究专项(23NLTSZ001);甘肃省气象局区域数值预报创新团队(GXQXCXTD-2024-03)共同资助。

摘　　要：利用2020年7月10日甘肃省陇南市站点逐小时降水观测及ERA5再分析资料,分析了强降水时空分布、环流形势及水汽输送等特征,并引入大气湿位能(Moist Static Energy,MSE)研究了对流活动的不稳定能量来源。结果表明:(1)此次强降水过程具有强度大、局地性明显和对流性强等特征;500 hPa受高原短波槽影响,冷暖空气交汇明显,700 hPa为偏南气流并配合有气旋性切变,具备较好的水汽和动力抬升条件。(2)强降水发生伴随MSE充放能过程,强降水到达峰值前MSE不断累积,大气处于充能状态;到达峰值后MSE明显减弱,大气处于放能状态。(3)不同垂直高度的大气充能机制存在差异,对流层低层MSE垂直输送起正贡献,水平平流为负贡献;中层水平平流为正贡献,且以经向平流为主,垂直输送为负贡献;高层MSE增加主要由纬向平流引起。(4)对流层低层MSE受水汽垂直输送的影响;中层MSE受水汽相关的潜热能控制,MSE增加主要为偏南风异常造成水汽经向平流;高层MSE由内能项主导,MSE增加主要由西风叠加西暖东冷的温度梯度造成纬向平流所致。This study analyzes the spatial and temporal distribution,circulation patterns,and water vapor trans-port characteristics of a heavy precipitation event in Longnan City,Gansu Province,on July 10,2020,using hour-ly precipitation observations and ERA5 reanalysis data.Additionally,atmospheric moisture energy(MSE)was in-troduced to investigate the unstable energy sources of convective activity,providing a new perspective for the re-evaluation and diagnosis of severe convective weather in the northwest region,as well as new reference indica-tors for business forecasting.The results show that:(1)The heavy precipitation exhibited high intensity,obvious locality,and strong convection.At 500 hPa,the plateau shortwave trough facilitated the convergence of cold and warm air,while at 700 hPa,the southerly airflow combined with cyclonic shear provided favorable conditions for water vapor transport and dynamic uplift.(2)The occurrence of heavy precipitation was accompanied by MSE charging and discharging.The MSE accumulates continuously before the peak of heavy precipitation,putting the atmosphere in a charging state.After peaking,the MSE significantly decreased,and the atmosphere was in a state of energy release.(3)The mechanisms of atmospheric charging differed by vertical height,with vertical MSE transport in the lower troposphere contributing positively,whereas horizontal advection contributing negatively.Horizontal advection,particularly meridional advection,positively contributed to the middle layer,whereas verti-cal transport contributed negatively.The increase in MSE transport in the upper troposphere is mainly driven by meridional advection.(4)The vertical transport of water vapor influenced the MSE in the lower troposphere,whereas the latent heat energy from water vapor controlled MSE in the middle layer.The meridional advection of water vapor increases the MSE due to abnormal southerly winds.High-level MSE is dominated by the internal en-ergy term,and the main contribution to the increase in MSE is the meridional ad

关 键 词：强降水 大气不稳定能量 湿位能 水汽通量 西北地区 

分 类 号：P426.6[天文地球—大气科学及气象学]