An Analysis On Change Of Trend Coefficient Of Extreme Climate Events In China

Based on the data of dally temperature and precipitation from year 1955 to 2005,the spatial and temporal features of trends of extreme climate events are studied, andthe major conclusions are summarized as follow:1. (1) Results show that the stable increasing trends of annual and seasonalextreme minimum temperatures are found all over China in the spacial structure.Decreasing trends of extreme maximum temperatures are obvious in the lowerreaches of the Yellow River in year, spring and summer: on the other side, increasingtrends of extreme temperatures are obvious in south China and northwest China.(2)Generally, increasing trends of extreme temperatures in the temporal change aredetected, and increase in extreme minimum temperatures is more dominant than thatin extreme maximum temperatures. Increasing trends of extreme temperatures arefound in every season, especially in winter. Further analysis suggests thatinterdecadal variations in extreme maximum and minimum temperatures aregenerally consistent.2. (1) There are good relations in the changes between extreme temperatures andtheir frequences in the special structure; (2) In the temporal change, the trends offrequences of extreme minimum temperature events, but it is contrary in thefrequences of extreme maximum temperature events.3. (1) The trends of intensities and frequences of extreme precipitation events aredecreased in the north China, Shandong Province and the Great Bend of the HuangheRiver, but obviously increased in the north of northwest China in the special structure;(2) The researches about the extreme precipitation events show that the long-termchange of annual extreme precipitation events has two different periods in thetemporal change: Decreasing trends are found before the end of 70th in the 20thcentury, but increasing trends are detected after that time; (3) As a whole, the events of heavy rain and rainstorm is decreased in north China, but increased in south China.4. (1) Increasing trends of average temperatures, especially of average minimumtemperature, are found all over China in the special structure; (2) There are obviouspositive relations between average temperatures and frequences of extremetemperature events, except for the obvious negative relation between averagetemperature and frequence of extreme minimum temperature at night; (3) Comparedwith annual average temperature, the mean of seasonal average temperature havecloser relations to the extreme temperature events.