APPLICATION OF GENERALIZED CONVECTIVE VORTICITY VECTOR IN A RAINFALL PROCESS CAUSED BY A LANDFALLING TROPICAL DEPRESSION  

作　　者：喻自凤 余晖 

机构地区：[1]Key Laboratory of Meteorological Disaster of Ministry of Education,Nanjing University of Information Science&Technology [2]Shanghai Typhoon Institute/Laboratory of Typhoon Forecast Technique,China Meteorological Administration

出　　处：《Journal of Tropical Meteorology》2012年第4期422-435,共14页热带气象学报（英文版）

基　　金：The State 973 Program (2009CB421505);National Natural Sciences Foundation of China (40921160381,40875039,40905020,41005033,40905029);Projects for Public Welfare (Meteorology) of China (GYHY200906002,GYHY201006008);Shanghai Meteorological Bureau (MS201202);Fund for Graduate Renovative Education of Jiangsu Province

摘　　要：A heavy rainfall process, which occurred in Shanghai during 5-6 August, 2001 from a landfalling tropical depression (TD),is examined with a control numerical experiment based on MM5 model. It is found that the contours of generalized equivalent potential temperature (θ*) are almost vertical with respect to horizontal surfaces near the TD center and more densely distributed than those of equivalent potential temperature (θe).Because the atmosphere is non-uniformly saturated in reality, θ* takes the place of θe in the definition of convective vorticity vector (CVV) so that a new vector, namely the generalized convective vorticity vector (CVV*), is applied in this study. Since CVV* can reflect both the secondary circulation and the variation of horizontal moist baroclinicity, the vertical integration of vertical component of CVV* is found, in this study, to represent the rainfall areas in the TD case better than potential vorticity (PV), moist potential vorticity (MPV), generalized moist potential vorticity (Pm), and CVV, with high-value area of CVV* corresponding to heavy-rainfall area. Moreover, the analysis from CVV* implies that the Hangzhou Bay might play an important role in the heavy rain process. A sensitivity experiment without the Hangzhou Bay is then designed and compared with the control run. It is found that the CVV* becomes weaker than that in the control run, implying that the elimination of Hangzhou Bay results in reduced rainfall. Further analyses show that the Hangzhou Bay provides sufficient water vapor and surface heat flux to the TD system, which is very important to the genesis and development of mesoscale cloud clusters around the TD and the associated heavy rainfall.A heavy rainfall process, which occurred in Shanghai during 5-6 August, 2001 from a landfalling tropical depression （TD）, is examined with a control numerical experiment based on MM5 model. It is found that the contours of generalized equivalent potential temperature （θ ＊ ） are almost vertical with respect to horizontal surfaces near the TD center and more densely distributed than those of equivalent potential temperature （θe）. Because the atmosphere is non-uniformly saturated in reality, θ ＊ takes the place of θe in the definition of convective vorticity vector （CVV） so that a new vector, namely the generalized convective vorticity vector （CVV＊）, is applied in this study. Since CVV＊ can reflect both the secondary circulation and the variation of horizontal moist baroclinicity, the vertical integration of vertical component of CVV＊ is found, in this study, to represent the rainfall areas in the TD case better than potential vorticity （PV）, moist potential vorticity （MPV）, generalized moist potential vorticity （Pm）, and CVV, with high-value area of CVV＊ corresponding to heavy-rainfall area. Moreover, the analysis from CVV＊ implies that the Hangzhou Bay might play an important role in the heavy rain process. A sensitivity experiment without the Hangzhou Bay is then designed and compared with the control run. It is found that the CVV＊ becomes weaker than that in the control run, implying that the elimination of Hangzhou Bay results in reduced rainfall. Further analyses show that the Hangzhou Bay provides sufficient water vapor and surface heat flux to the TD system, which is very important to the genesis and development of mesoscale cloud clusters around the TD and the associated heavy rainfall.

关 键 词：tropical cyclone generalized convective vorticity vector （CVV＊） RAINFALL LANDFALL 

分 类 号：P444[天文地球—大气科学及气象学]