Extreme Temperature Events in Chongqing and Their Relation with the Mean Temperature and Precipitation Change Based on Granger Causality Test

The threshold of extreme temperature events was defined by percentile and agrometeorological service,according to the series data of daily temperature and precipitation in Chongqing from 1951 to 2010.The statistical results showed that the trends of the extreme temperature events defined by two methods were featured with similarity.The trends appeared that the extreme maximum temperature events in 1980s-1990s were relatively few and the strength was relatively weak in 1980s,which was opposite to that in other periods.The Granger Causality Test was used to analyze the relation between the extreme temperature events and the change of mean temperature and precipitation,and the results showed that the causes of the rise of annual average temperature were the rise of frequency of extreme maximum temperature events and the fall of frequency of extreme minimum temperature events,and also the weakening of the strength of the extreme minimum temperature events.It was also showed that the strength of the maximum temperature events was the cause of precipitation change in statistical sense.The Granger Causality Test is a new statistical method to analyze the relationship of different events.