Climate Changing Trend in Wet and Dry Seasons in the Manas River Basin in 1959-2007

The changing tendencies,periods and abrupt changes of wet season mean,dry season mean and annual mean air temperatures,precipitations and arid index were analyzed for the Manas River basin,by means of linear analysis,annual anomaly,wavelet analysis and abrupt t test from 1959 to 2007.It is found that temperature and precipitation increased in the Manas River basin during this period,with the decadal changing rates of 5.91 mm·(10a)-1 and 0.33 ℃·(10a)-1,respectively;Climatic dry-wet condition varied in a normal range.With precipitation decrease,there was a dry phase in the 1970s.The time series of temperature,precipitation and arid index of wet season mean,dry season mean and annual mean varied with a long period,which contained some short ones.Among them,there were evident periods of 8 and 14 years for temperature and arid index,however,the time series of annual mean air temperature was rather complicated and showed a period around 22 years.The abrupt change years of climate factors derived from annual cumulative anomalies and abrupt t test are identical,in the 1980s.Owing to precipitation changing form less to more,the climate in the Manas River basin became wetter in 1983.The air temperature changed form cold to warm in 1988.