Basic characteristics of major climatic factors on Qinghai-Tibet Plateau in recent 45 years

This paper analyzed basic characteristics of major climatic factors on the Qinghai-Tibet Plateau during 1961～2005.The result are shown as follows.In the past 45 years,the annual mean temperature was on the rise,with a rate of 0.265℃/10a.The warming tendency in winter was remarkable and that in spring was faint.The temperature rise from 1980 to 2005 was higher than that from 1961 to 1980 and from 1961 to 2005,indicating that there has been a warming trend since the 1980s.In the 45-year period,the annual mean precipitation on the Qinghai-Tibet Plateau was on the faint rise,with a rate of 8.21 mm/10a;annual mean precipitation from 1961 to 1975 was below the average,that from 1975 to 1989 held the line and that after 1990s above the average.Generally speaking,precipitation in spring and winter tended to increase,but the tendency in spring was far greater than that in winter.Annual mean precipitation showed a certain periodicity.At 32 sites on the Qinghai-Tibet Plateau existed a 2～4a short cycle,at 11 sites a 5～8a medium cycle and at 6 sites a long cycle of above 10a.From 1961 to 2005 climatic synthetic tendency was mainly warming-wetting,with sites accounting for 67% of the all.