Study On Extreme Temperature And Precipitation Events In Sichuan Basin

The research on extreme temperature and precipitation events plays an important role in research fields on climate change. In past several decades, the climate got warmer, resulting in that the extreme temperature and precipitation events changed to be variable and complex. The extreme temperature and precipitation events frequently happen in China, leading a very serious influence on social economy and people’s property and life. So the importance of strengthening research on extreme temperature and precipitation events not only exists in science research, but also in practical application.This paper is based on the daily temperature and precipitation series of Chengdu, Nanchong and Shapingba station from1956to2010, which are3representative weather stations in Sichuan Basin. The main purpose and content is to analyze the change trends of extreme temperature and precipitation events on time scales and spatial scales in past55years, using statistical analysis such as the linear trends, six-order polynomial, Mann-Kendall test and wavelet analysis. Also, the relationship between extreme climate events and regional climate change is concentrated in this paper, using Granger causality test which has been widely used in economic research. The inclusion can be identified as follows:(1) The frequency of extreme high temperature events was relatively less and the strength was relatively lighter in the period from middle of1970s to1980s, while contrary in the period behind the late1990s. The change trends of extreme low temperature events were opposite. The frequency of extreme low temperature events between1970s and1980s was relatively more and the strength was relatively stronger, and it was contrary behind late1990s. The increase of extreme high temperature events appeared obviously in northwest part of Sichuan Basin, but the extreme high temperature events most happened in northeast part and the strength of extreme high temperature events was most serious in south part of Sichuan Basin. As for extreme low temperature events, the frequency was relatively largest in south part of Sichuan Basin, but the strength was relatively less serious, and it was opposite in northwest part.(2) The extreme rainy events in different parts of Sichuan Basin differed from each other, the frequency of extreme rainy events in the northern basin was largest, especially in1970s and1990s in last55years, while relatively less in1960s and1980s. The trends was opposite in northwest part of Sichuan Basin. The extreme rainy events in northwest of Sichuan Basin strengthened in1960s and mitigated in the period behind middle of1990s, while it was opposite in south part of Sichuan Basin. The place where the extreme little precipitation events most happened was the northwest basin, the south basin was the place where the extreme little precipitation events least happened but the strength was strongest. In past55years, the extreme little precipitation events less happened in1980s and the strength is relatively less serious, while more happened with a stronger strength in1960s and the period behind middle of1990s.(3) The causes that lead higher temperature can be attributed to the increased frequency and severity of extreme high temperature events, as well as the decreased frequency and severity of the extreme low temperature events. The increase of extreme high temperature events can result in the decrease of precipitation, while the decrease of precipitation can also result in the increase of extreme high temperature events. The higher temperature was the important factor that contributed to the increased frequency and severity of extreme little precipitation events. The increase of precipitation was the result of the increased frequency and severity of extreme rainy events and also the cause of the severity of extreme rainy events, the less severity of extreme little precipitation was also the cause of the increase of precipitation. The increase of precipitation can result in the severity of extreme rainy events.