A Study On Typhoon Torrential Rain Over China During The Last About 50 Years

The severe rainfall company with a typhoon is the primary cause of itscatastrophic influences. At the same time, typhoon torrential rain is a kind ofimportant precipitation form in Middle and Eastern China. Studying the climatecharacteristic of the Chinese typhoon torrential rain, primary meaning lies in disasterprevention and reduction; In addition, there is important value to distinguishing andunderstanding the climate change of our country. This study deals with typhoons that influence China and focus on correspondingprecipitation situation during 1951-2001, with the method of climate diagnosing. Itsummarizes the spatial-temporal characteristics of the Chinese typhoon torrential rainin the latest about 50 years; and discusses the influencing climatic background factorswhich impact on its variation. The major conclusions of this study are as follows: (1) The geographical distribution of the Chinese typhoon torrential rain is veryuneven. The frequency of typhoon torrential rain shows a decrease trend fromsoutheast coastal district to the northwest inland gradually; and the frequency in thecoastal area is the highest at the same latitude. There isn't evident distinction indifference region, on the maximum intensity of typhoon torrential rain; in averageintensity, some areas of North China and south of Northeast China are generallyhigher than South China or East China. (2) The main season of Chinese typhoon torrential rain is from May to November,especially between July and September. The frequency of typhoon torrential rain hasstrong interannual and interdecadal oscillation. On the long terms, the frequency andintensity of typhoon torrential rain both demonstrate the trend of increasing, but notsignificant in statistics; In addition, the frequency and intensity of torrential rain showsome cycles, unsignificantly yet. (3) The systematic characters of the typhoon have influences on the behavior oftyphoon torrential rain in many aspects. As regards the frequency of the typhoontorrential rain, typhoon frequency and the range and time that typhoon influenced areboth important factor; And the latter include the route, move speed and disappearingspeed of a typhoon. (4) The oceanic influences on the typhoon and the torrential rain are self-evident.There is restricting relations between the Pacific Ocean sea surface temperatureanomaly and Chinese typhoon torrential rain variation. And the activity of torrentialrain lags behind SST change, about one or two seasons. There is a constant relationbetween ENSO and Chinese typhoon torrential rain as well. In El Ni?o phase, theannual frequency of typhoon torrential rain seems to be lower; In La Ni?a phase, it'sreverse. This relation is more evidence in El Ni?o phase. II(5) The atmospheric circulation background is one of the important factors thatinfluencing precipitation. This study select SLP, 500hPa potential height and 30hPalatitudinal wind, to represent low, middle and high layer of atmospheric circulationvariable respectively. These variables all have obvious connections with the Chinesetyphoon torrential rain variation. There are common characteristics between typhoontorrential rain and each of them, that is, a teleconnection exist between the previouswinter circulation field and the typhoon torrential rain; and a contemporary relationexist in summer as well. These relations are prominent in some location. Especially,for Western Pacific subtropical High, that is an important circulation systeminfluencing China, also have a remarkable relation to the typhoon torrential rain insummer. If the WPSH leans towards strongly in summer, the typhoon torrential rainover China is on the weak phase. We also studied the relationship between typhoontorrential rain and QBO, and found this relation can be summed up for two respects:(a) As QBO is at the whole year east wind phase or transferred from west to east, thefrequency of typ...