基于热指数多时空尺度的蒸散发模型构建及其应用研究

许多蒸散发（ET）模型具有高度的尺度依赖性，不同尺度间ET转换方法的构建和检验是蒸散发研究中的难点。BTA是一个简化的机理性蒸腾模型，因缺乏指示土壤水分亏缺的变量，模型在水分变化幅度大时模拟效果差。基于“叶片冷却效应”原理，通过热遥感数据估算的热指数可被用于指示植被水分状况。本项目旨在将热指数响应函数与BTA模型结合，发展一个适用于不同水分条件和多时空尺度估算蒸散发的BTA-TI模型。拟开展三个主要研究内容：（1）基于热指数构建BTA-TI模型，利用小时尺度和日尺度试验数据评估模型在单木尺度估算蒸腾的性能；（2）在生态系统尺度，探索适合BTA-TI模型估算蒸散发的环境条件并分析不同生态系统蒸散发的敏感性因素；（3）量化BTA-TI模型在区域尺度估算ET的不确定性并探索模型的不确定性源。本项目研究结果对于气候变化背景下，制定有效的农林用水管理策略、量化地表能量和水分收支有重要意义。

Many approaches of evapotranspiration (ET) estimates are highly scale-dependent. The construction and validation of transferable ET models across different spatial and temporal scales have become difficult problems in the field of ET research. There is a simplified process-based transpiration model (hereafter BTA) that fails to simulate transpiration under a wide range of root zone soil water conditions, due to a lake of an index to represent soil water conditions explicitly. The thermal index can represent plant water stress and can be accessed in multi-spatial-temporal scales. This program is aimed to develop a new model (hereafter BTA-TI) to estimate ET under different water conditions and in multi-spatial-temporal scales by combining a thermal index and the BTA model. There are three main research contents: (1) establishing the BTA-TI model based on the thermal index response function and evaluating the performance of BTA-TI in plant water use estimation at tree scale based on field site hourly and daily data; (2) exploring the appropriate environmental conditions of ET estimates with BTA-TI at ecosystem scales and the sensitive factors of ET across different ecosystems; (3) quantifying the uncertainty of ET estimation with BTA-TI in regional scale and exploring the sources of uncertainty of the BTA-TI model. Results of this program will be meaningful for the development of agricultural and forestry water management strategies and the quantification of surface energy and water budgets under climate change.