Analysis of the Variation Characteristics of the Temperature and Rainfall in Mengding Basin over Recent 54 Years

Based on the temperature and rainfall data from 1955 to 2008 in Mengding Basin,the spatial-temporal variation characteristics,variation trend,annual change and mutation characteristics of temperature and precipitation were analyzed under the background of global warming by using regression analysis,variance analysis and M-K test method. The results showed that: climate warming trend was obvious over recent 54years,the annual average temperatures rising by 1. 5 ℃. Warming trend was particularly significant since the late 1990s and the largest contribution to heating was made in winter. Both the annual average temperature and seasonal mean temperature passed 99. 9% reliability test. Precipitation decrease trend was obvious in past four years and since 2000 it was the most remarkable. The annual precipitation decreased by 103. 68 mm.Precipitation tend to increase in spring but tend to decrease in summer,autumn and winter among which it decreased most obviously in summer.Precipitation in summer and autumn was above 99. 9% reliability test but the annual average temperature and seasonal mean temperature were under the reliability test. Annual and seasonal mean temperature and rainfall had one or more mutation points. It was obvious that temperature mutation tend to increase since the 1990s. Annual and seasonal mean temperature was more than 0. 01 critical path. The rainfall mutation in spring increased significantly since the 1970s. Annual and seasonal mean rainfall mutation began to decrease since mid 1980s.