A Study On The Environmental Field Values Affecting The Producing Of Rainstorm

Rainstorm is a kind of common weather processes, consistent intensity rainstorm usually arises flood disaster, even leads to severe loss to the people's lives and property. Therefore, it is very important to study the producing and developing of the rainstorm. On the other hand, the relationship between environmental physical field values and the center of rainstorm is complex, consequently, it is difficult to solve such problems, for example, how to develop the relationship between environmental physical field values and rainstorm? How to form rainstorm? How much rainstorm will be produced? When will each environmental physical field value impact the amount of rainstorm? To these problems, traditional methods, such as weather graph models and numeric weather forecasting methods, are limited. However, spatial data mining is a new application technology and develops quickly in recent years. Therefore, it is a great meaning to solve difficult problems in meteorology using deferent knowledge. In this project, T106 data and daily rainfall data in Yangtze River (110° E~ 123°E, 24° N~34°N) Basin are used from June to August between years of 1998 to 2000. Based on these, the daily rainfall database and environmental physical field values database are developed. And, the feature values of environmental physical field are abstracted and decision tree is applied to set up the relationship between rainfall of rainstorm center and environmental physical field values.In this paper, nine parameters, including geopotential height, temperature, vorticity, divergency, relative water vapor flux divergence, pressure on the ground level, 9 se, K index and relative humidity at the level of 500hPa, are used to study the relationship between rainstorm and environmental physical field values. Among these data, the spatial resolution is 1°lat x1° long and time resolution is twenty four-hour. Based on these, the spatial distribution of each environmental physical field value and rainfall in study area is obtained to discuss the relationship between them. The results indicate that the relationship is undistinguishable and uncertain. Consequently, decision tree is used to reveal the basic theory of causing rainstorm. The results show that it is different of environmental physical field values influencing rainstorm in different area. And, environmental physical field values are also different around rainstorm center in different distance. Therefore, it has great meaning in choosing environmental field factors for regional disaster weather forecasting.