Characteristics of climatic variation in Tibet area for last 52 years

Based on the data of temperature and precipitation of 38 stations in Tibet from 1955 to 2007,the seasonal variation trends and their seasonal differences of temperature and precipitation were analyzed,and significance test also was carried out.The linear trend estimation indicates that annual mean temperature,minimum and maximum temperature had an evident warming trend,especially the mean minimum air temperature.Annual mean precipitation,minimum and maximum precipitation had an increase trend.Mann-Kendall analysis shows that from the end of 1980's,annual mean and seasons air temperature appeared to be a transition,the warming was more evident since the middle of 1980's.From the end of 1960's,winter,spring and summer precipitation appeared to be a transition,precipitation increase was more evident since 1970.