A STUDY OF PARTITIONING Q VECTOR ON BACKGROUND CONDITIONS OF A TORRENTIAL RAINFALL OVER SHANGHAI,CHINA ON 25 AUGUST 2008  

作　　者：岳彩军 鲁小琴 李小凡 宗志平 

机构地区：[1]Shanghai Typhoon Institute of the China Meteorological Administration [2]Laboratory of Typhoon Forecast Technique/CMA [3]Joint Center for Satellite Data Assimilation and NOAA/NESDIS/Center for Satellite Applications and Research,Camp Springs [4]National Meteorological Center of CMA

出　　处：《Journal of Tropical Meteorology》2011年第3期231-247,共17页热带气象学报（英文版）

基　　金：National Natural Science Foundation of China(40875025,40875030,40775033,40921160381);Shanghai Natural Science Foundation of China(08ZR1422900);Key Promotion Project of New Meteorology Technology of the China Meteorological Administration in 2009(09A13)

摘　　要：A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector(DQ)and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural coordinate to identify different scale forcing in adiabatic atmosphere,and the large-scale and convective condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating that includes radiative heating and other heating and cooling processes,are calculated to study the forcing from diabatic heating.The effects of the environmental conditions on the development of the rainfall processes are diagnosed by performing the partitioning of Q vector based on 6-hourly NCEP/NCAR Final Analysis(FNL)data with the horizontal resolution of 1°×1°.The results include the following:(1)a low-pressure inverted trough associated with the landfall of Typhoon Nuri (2008),a strong southwesterly jet along the western side of the subtropical high,and an eastward-propagating westerly low-pressure trough provide favorable synoptic conditions for the development of torrential rainfall;(2)the analysis of DQ vector showed that the upward motions forced by the convergence of DQ vector in the lower troposphere(1000–600 hPa)favor the development of torrential rainfall.When DQ vector converges in the upper troposphere(500–100 hPa),upward motions in the whole air column intensify significantly to accelerate the development of torrential rainfall;(3)the partitioning analysis of DQ vector reveals that large-scale forcing persistently favors the development of torrential rainfall whereas the mesoscale forcing speeds up the torrential rainfall;(4)the calculations of large-scale A rainfall that occurred during 0200–1400 Beijing Standard Time（BST）25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h- 1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector（DQ）and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural coordinate to identify different scale forcing in adiabatic atmosphere,and the large-scale and convective condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating that includes radiative heating and other heating and cooling processes,are calculated to study the forcing from diabatic heating.The effects of the environmental conditions on the development of the rainfall processes are diagnosed by performing the partitioning of Q vector based on 6-hourly NCEP/NCAR Final Analysis（FNL）data with the horizontal resolution of 1°×1°.The results include the following：（1）a low-pressure inverted trough associated with the landfall of Typhoon Nuri （2008）,a strong southwesterly jet along the western side of the subtropical high,and an eastward-propagating westerly low-pressure trough provide favorable synoptic conditions for the development of torrential rainfall;（2）the analysis of DQ vector showed that the upward motions forced by the convergence of DQ vector in the lower troposphere（1000–600 hPa）favor the development of torrential rainfall.When DQ vector converges in the upper troposphere（500–100 hPa）,upward motions in the whole air column intensify significantly to accelerate the development of torrential rainfall;（3）the partitioning analysis of DQ vector reveals that large-scale forcing persistently favors the development of torrential rainfall whereas the mesoscale forcing speeds up the torrential rainf

关 键 词：background conditions of torrential rainfall partitioning of Q vector dry ageostrophic Q vector diabatic heating 

分 类 号：P456.7[天文地球—大气科学及气象学] P441