Study on Abrupt and Periodic Changes of Temperature and Precipitation in the Qaidam Basin

Using air temperature and precipitation data from 1954 to 2003 of 6 meteorological stations in Qaidam basin,the changing trend as well as abrupt and periodic changes of temperature and precipitation processes of the basin in recent 50 years are analyzed.The results show that the increasing trend of annual and seasonal mean temperature in summer,autumn and winter are significant at 0.01 level,while the increasing trend of spring temperature and the decreasing trend of annual temperature anomaly are significant at 0.05 level.In the precipitation processes,annual and summer precipitation exhibits an increasing tendency at the 0.10 significance level.Abrupt change occurred in every temperature series.An abrupt warming at the 0.001 significance level took place in the early 1980s in annual mean temperature.The abrupt changes in autumn and winter are more significant than that of spring and summer temperature.The jump in winter temperature is earlier than that in other seasonal temperature and the jump in annual temperature anomaly is earliest in all temperature series.For the annual precipitation,an abrupt change occurred in 1976.There are jumps in spring and summer precipitation while there aren't in autumn and winter series.The tests on periodic changes indicate that the major periods of annual mean temperature are 12 years,7 years and 3 years in order by intensity and that of annual precipitation are 9 years and 4 years.