Abstract: In this study,the ERA-Interim reanalysis data and the observation data from 43 meteorology stations in Qinghai Province from 1981 to 2010 were used. The purposes of the study were to analyze the spatial and temporal distribution characteristics of the surface latent heat flux (short for slhf) over the Qinghai-Tibetan Plateau and its relationship with precipitation in Qinghai from May to October using the method of EOF (Empirical orthogonal functions),correlation analysis and composite analysis. The result showed that: ① The spatial distribution of first order mode of slhf was different in the eastern and western regions of the plateau,the anomaly was positive in northeast Qinghai and the western and southern regions of the plateau but negative in other areas. The time coefficient of first order mode was in a significant downward trend,it was positive before 2001 but negative after that,which revealed that the slhf in northeast Qinghai and the western and southern parts of the plateau increased before 2001 but decreased after that; ② There was a significant negative correlation between the slhf over the plateau and the precipitation in northeast Qinghai Province. When the slhf over the plateau was increased (or decreased),the precipitation in northeast Qinghai was reduced (or increased); ③ The area where it passed the significance test of 0.1 was regarded as the key area (35.0°-38.5°N,98°-103.0°E) to study the relationship between the two,and 1 standard deviation was used to select the high-value years and low-value years of slhf. The results revealed that the slhf in the key area in recent 35 years was in a significant decrease trend,the precipitation in the key area was increased in the high-value years of slhf,it was decreased in the northeastern part of the key area but increased in other regions,and there was a 60 mm positive anomaly center in the south; ④ In the high-value (or low-value) years of slhf,the potential of the key area was low (or high),the wind speed was high (or low),and the water vapor convergence was weak (or strong) in the south of the key area. Analysis of the intensity of the 100 hPa South Asian High Center and the 300 hPa temperature field revealed that the intensity of the South Asian High and the 300 hPa warm center were slightly lower (or higher) in the years when the slhf was abnormally high (or low),and the establishment (or retreat) of South Asian High was earlier.

Key words: Qinghai-Tibetan Plateau, surface latent heat flux, Qinghai, precipitation, South Asian High, atmospheric circulation