Evaporation and energy balance estimates over a large inland lake in the Tibet-Himalaya

The process of evaporation from the lake surface is one of the main mechanisms in the energy and water budgets of the lake hydrologic cycle, and an essential component of the water balance especially for inland lakes. In this study, using routine meteorological data as input, a one-layer potential evaporation model was employed to simulate evaporation and energy fluxes over Lake Yamdrok Yumco, the largest high-elevation inland lake in the mountain area of the Tibet-Himalaya in China. Then, the calculation results were compared with the measured values from a big pan evaporator of 20 m(2) near the lake. The results show that the average annual input radiation flux R-down arrow is 128.2 W m(-2), the lake storage heat flux G is 19.4 W m(-2), the sensible heat flux H is 20.4 W m(-2) and the latent heat flux lE is 107.8 W m(-2). The R-down arrow and G exhibit similar seasonal variations. The lE reaches a maximum in October, lagging nearly 4 months behind the R-down arrow and the G, which indicates the large heat capacity of the lake. The simulated annual evaporation ranges from 1,113.2 to 1,429.1 mm and its mean value is 1,252.5 mm during 1961-2005. The simulated annual evaporation is in good agreement with the measured value, and the measured average lake temperature is as expected when compared with the measured lake surface temperature.