Guangdong Province, Nearly 40 Years Of Extreme Temperature And Precipitation Variation Analysis

Based on the daily maximum and minimum surface air temperature data and precipitation data at 76 observational stations of Guangdong province from 1962 to 2004, with the thresholds of extremes are estimated according to the 95th and 5th percentiles of non-parametric distribution, and using the methods of REOF and Wavelet analysis, the spatial and temporal variation of the extreme temperature and precipitation are analyzed. The main conclusions are summarized as follows:(1) The maximum and minimum extreme temperature both have a warming trend and remarkable characteristics of inter-annual and inter-decadal change in recent 43 years. The spatial distributions of the trend-coefficients show that, the regional differences of extreme high temperatures are obvious compare to that of extreme low temperatures.(2) There are distinct differences of the trends of extreme temperature variation between different regions, but the periodic variation analysis show that the inter-decadal variations are consistent.(3) The frequencies of extreme high temperature event in day and night in summer increase obviously, and that of extreme low temperature event in winter night decreases obviously. The spatial distributions of the frequency trend-coefficients of extreme temperature events have opposite relation with that of the extreme temperatures.(4) By studying relationship between the extreme and the mean and variability of daily temperatures, the results reveal that in the north of Guangdong the increase of mean value cause the increase of extreme low temperature;in littoral, the mean value and variability increased obviously, as a result, extreme high and low temperature both increased.(5) The trend analysis shows that there are no obvious trend variations of all the extreme precipitation indexes. The Morlet Wavelet analysis results show that all the indexes have complex periodic variations.(6) All the extreme precipitation indexes have distinct different trends and periodic variations in different regions.(7) By studying the relationship between annual rainfall amount and rainfall amount of 5 intensity categories, the results show that in the north of Guangdong the increases of storm and heavy storm rainfall are the main cause of the increase of annual rainfall amount. In the central of Guangdong the decreases of storm and heavy storm rainfall are the main cause of the decrease of annual rainfall amount.