青藏高原大型湖泊蒸发量的观测与模拟研究

湖泊蒸发量是青藏高原内陆湖泊水量平衡的重要支出项，对流域水分循环和水量平衡研究至关重要。目前，青藏高原大型湖泊蒸发量（尤其是冰面升华量）观测严重缺乏，遥感估算和模型模拟因缺少资料验证而存在很大的不确定性，同一湖泊蒸发量估算结果差异显著。本项目将基于高原中西部三个湖泊（纳木错、巴木错、拉昂错）湖气相互作用过程（包含结冰过程）观测（风、温、湿、压、辐射观测、涡动水热通量观测、水温链观测），对比分析三个湖泊热力分层结构、水热通量季节变化及其影响因素的异同；进而结合卫星遥感算法（总体传输法和能量平衡法）和湖泊模型（Flake和WRF-Lake），改善湖泊水热通量（包括冰面升华）模拟效果，探究湖泊蒸发量的空间分布规律、变化趋势及其水资源总量。研究项目将为青藏高原湖泊的区域气候效应研究和“亚洲水塔”水资源评估奠定基础。

Lake evaporation is an important loss item in the water balance of high-elevation inland lakes on the Tibetan Plateau (TP), and it shows significance for the study of water cycle and water balance in the lake basin. At present, the in situ measurements of lakes’ evaporation amounts (especially the ice sublimation) are seriously limited. Thus lake evaporation estimation by satellite algorithms and model simulations has great uncertainty due to lack of verification data, and the estimated values over a same lake show significant differences. This study will set up instruments for the lake-atmosphere interaction process (including the ice-atmosphere interaction process in winter) in the lakes of the central and western TP (Lake Nam Co, Lake Bam Co and Lake Ngangla Ring Co), collect the detailed dataset of meteorological variables (wind speed and direction, air temperature, air humidity, air pressure and radiation components), eddy covariance data (sensible and latent heat flux) and water temperature gradients, and analyze the thermal stratifications, the seasonal variations of water and heat fluxes and their influencing factors comparatively. We will further make usage of satellite algorithms (bulk transfer algorithm and energy balance method) and lake models (Flake and WRF-Lake), improve the performances of lake models on the lake-atmosphere (including ice-atmosphere) interaction simulation, and explore the temporal and spatial variations, trends and total amounts of lake evaporations. The research project will lay a foundation for the study of regional climate effect of high-elevation lakes and the assessment of water resources in the “Asia’s water tower”.