青藏高原季风和西风控制区典型湖泊蒸发的控制因子对比研究

Since the middle of 1990s, the Himalayan region lakes affected by the South Asia monsoon have shrunk, while the Tibetan Plateau (TP) interior lakes affected by westerlies have expanded. For the TP which possesses a large number of lakes, it is of importance to quantify the contribution of lake evaporation to water budget change. Due to harsh environment, long-term lake evaporation is seldom observed. Therefore, the simulation of lake evaporation, based on observation, is extremely urgent. This project will study different controlling factors on lake evaporation between the monsoon-dominated and westerlies-dominated zones, and the contribution of inter-decadal variation of lake evaporation to lake water budget change. This research includes three parts: (1) evaluating the capability of three one-dimensional lake models (Flake, CEMS-Lake, CoLM-Lake) to simulate evaporation on Nam Co Lake; (2) calibrating the model parameters with MODIS lake surface temperature products; (3) modeling the long-term evaporation of Nam Co Lake, Yamdro Yumco Lake and Peiku Co which are located in monsoon-dominated zone, Bangong Co Lake and Dagze Co Lake which are located in westerlies-dominated zone, and then analyzing the seasonal, inter-annual and inter-decadal variations of lake evaporation and its controlling factors for above five lakes. This research will help to understand the trend of lake water budget change.

1990年代中期以来，受季风控制的青藏高原南部湖泊普遍收缩，而受西风控制湖泊普遍扩张。在分布众多湖泊的青藏高原，研究湖泊蒸发对理解湖泊水量变化的影响尤其重要。由于环境条件艰苦，长期可靠的湖泊蒸发观测数据十分匮乏，因此基于观测的蒸发模拟研究十分迫切。本项目拟研究高原不同气候区湖泊蒸发的控制因子，并从蒸发的年代际变化分析其对湖泊水量平衡变化的贡献。主要研究内容包括：(1) 在观测资料丰富的纳木错，定量评估三个湖泊模型 (Flake, CEMS-Lake，CoLM-Lake)的蒸发模拟能力；(2) 用长序列的MODIS湖面温度数据对模型参数进行标定；(3) 用标定好的湖泊模型，在高原季风控制区的纳木错、羊卓雍错和佩枯错与西风控制区的班公湖和达则错开展蒸发的长期模拟，对比分析湖泊蒸发的季节变化、年际变化和年代际变化及其控制因子。研究结果有助于理解湖泊水量变化趋势。

1990年代中期以来，青藏高原湖泊普遍扩张。在分布众多湖泊的青藏高原，研究湖泊蒸发对理解湖泊水量变化的影响尤其重要。由于环境条件艰苦，长期可靠的湖泊蒸发观测数据十分匮乏，因此基于观测的蒸发模拟研究十分迫切。本项目以改进湖泊模型使得模拟的湖面蒸发的更加准确为目标，包含以下三个主要研究内容和结果：(1)在纳木错湖泊非冻结期间，用观测的温度扩线资料，定量评估三个湖泊模型 (Flake, WRF-Lake，CoLM-Lake)，并改进模型。Flake模拟湖面温度的能力强，WRF-Lake模拟湖泊内部深度大于10m的水温的能力强；（2）用于模型参数标定的MODIS湖面温度数据进行验证，反演精度很高，但是卫星象元东移对小湖和狭窄湖泊的MODIS湖面温度的影响很大；(3) 发现青藏高原湖冰消融末期近表层湖水温度快速上升现象，并用正反馈物理机制解释，说明太阳辐射能够穿过湖冰加热湖水，这为下一步模型改进提供依据和方法。