A Study On The Relationship Between The Trajectories Of Mesoscale Convective System Over The Tibetan Plateau And Intensive Precipitation In The Yangtze River Basin

Strong convective weathers, for instance, heavy rainfall, hail, tornado, thunderstorm, etc., will cause severe disasters. Especially in China, every summer, continual and intensive precipitation will usually bring about severe flood disasters, grave loss to the life and property of people and the construction of national economy. Therefore, studying the features of spatial distribution and causes of heavy rainfall in summer in China is of great meaning to strengthen the ability of forecasting heavy precipitation and reduce the loss due to the disaster weather.In this paper, the trajectories of Mesoscale Convective System (MCS) over the Tibetan Plateau in China in summer 1998 are automatically tracked using GMS (Geostationary Meteorological Satellite) brightness temperature (Tbb). Based on these, clustering methods in spatial data mining, such as K-means and CLARANS, are used to analyze the characteristics of spatial distribution of environmental physical field values influencing MCS to move out of the Plateau and to the east. Furthermore, the relationship between the trajectories of MCS over the Tibetan Plateau and heavy rainfall process in Yangtze River Basin is discussed. These are of important theoretical and practical value to analyze the regulations of the trajectories of MCS over the Tibetan Plateau, reveal the reason of MCS origin and development, improve the predicted accuracy of heavy rainfall and intensive convective weather in Yangtze River Basin.Six chapters are included in this paper. Chapter one discusses recent study results of MCS and its relationship with heavy rainfall, based on these, methodology is provided. The fundamental principles of two spatial clustering methods, i.e. K-means and CLARANS, are represented in chapter two. Automatic tracking method of MCS is discussed in chapter three, on the basis of these, some information about MCS, including trajectories, size, shape, intensity, active regions, life characteristics etc., are obtained from June to August in 1998. And, spatial-time database of MCS and precipitation in Yangtze River Basin in summer 1998 is set up through GIS (Geographic Information System) software. In chapter four, environmental physical field values of influencing MCS to move out of the Tibetan Plateau and to the east are analyzed by K-means and CLARANS, therefore, the characteristics of spatial distribution of environmental physical field values aroundMCS over the Plateau in different stages, i.e., origination, development, and movement east out of the Plateau, are obtained to reveal the dynamic and thermal conditions favoring the trajectories and propagation of MCS over the Plateau. In chapter five, the relationship between the trajectories and propagation of MCS over the Plateau and heavy rainfall process in Yangtze River Basin is discussed, and the characteristics of dynamic field and thermal field around the heavy rainfall centers are analyzed to reveal the dynamic and thermal conditions causing heavy rainfall. In chapter six, the research results are concluded. Furthermore, future studies are discussed, too.