| 摘 要： |
Lake surface water-heat exchange and its climatic attribution critically influence alpine lakes' evaporation mechanism and water storage balance with climate change. Here, this paper first explored the hourly, daily, and monthly water-heat flux variations of the lake surface and their correlations with meteorological factors based on the eddy covariance turbulent flux observation over the Yamzhog Yumco, an alpine lake in south Tibet in the non-freezing period (April-December) in 2016 and 2017. We found that the average latent heat flux was much higher than the sensible heat flux on the lake surface from April to December. Meanwhile, the water-heat flux exhibited remarkable seasonal variation, with a prominent role of higher air temperature and humidity in summer jointly controlling the lake-air energy exchange. Moreover, the main controlling meteorological factors for the water-heat flux variation of the lake surface differed with diversified timescales. First, the lake-air temperature difference was the most significant meteorological factor related to sensible heat flux on the half-hourly, daily, and monthly timescales. Second, the latent heat flux was strongly positively correlated with wind speed and the synergies of wind speed and water vapor pressure deficit on the daily and half-hourly timescales. Third, the lake surface heat flux was significantly negatively correlated with net radiation flux on the daily and monthly scales. The negative correlation can be attributed to the seasonal variation of the water surface net radiation, and the phase difference in heat flux intensity caused by the lake-air temperature difference and heat capacity contrast. Our findings will hopefully improve the understanding of energy exchange and evaporation mechanisms for alpine lakes in a warming climate. |
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