基于极轨气象卫星与静止气象卫星数据的日尺度地表土壤热通量模型研究

The daily surface soil heat flux (G0) is an important variable for the study on the land surface energy balance, daily land surface evapotranspiration estimation and land atmosphere interaction. Due to the lack of in-depth research, some related models usually assume the soil absorbed energy is equal to the energy released during a day, which means the daily G0 is zero and it’s contrary to the fact. Diurnal variation of surface temperature affect the diurnal variation of surface soil heat flux and the existing G0 model method lack of the consideration of soil properties, soil moisture data and the extinction effect of vegetation. By considering soil properties and soil moisture data, a model for estimating G0 on a daily scale under bare soil condition was to build based on the data of domestic polar orbiting meteorological satellites and geostationary meteorological satellites. Based on the analysis of the effect of canopy on the solar short wave radiation, A half order model of G0 under the condition of vegetation coverage was to build. This study can make up for the lack of the study on the G0, to improve the surface soil heat flux on the regional scale estimation accuracy, the accuracy of surface evapotranspiration estimation can be improved by increasing the energy balance ration and it has important scientific significance to the study of water cycle research, hydrological process, land atmosphere interaction.

日尺度地表土壤热通量是地表能量平衡、地表蒸散发、地-气相互作用研究中的重要参数，受研究不够深入，目前相关模型通常假定日尺度地表土壤热通量均值为零，这与事实不符。地表土壤热通量日间变化同时受地表温度日变化过程的影响；且现有模型方法缺少综合考虑土壤属性参数、土壤水分数据以及植被的消光作用的影响；本研究基于国产极轨气象卫星与静止气象卫星数据，通过引入土壤属性、土壤水分数据，构建裸土状况下日尺度地表土壤热通量估算模型；通过分析冠层对太阳短波辐射的消减作用过程，构建植被覆盖状况下日尺度地表土壤热通量半阶法模型；本研究可弥补目前日尺度地表土壤热通量研究的不足，提高区域日尺度地表土壤热通量估算精度，提高能量平衡闭合率，进而提高地表蒸散发遥感估算精度，对水循环研究、水文过程、陆-气交互模式等研究具有重要的科学意义。

本项目基于极轨卫星与静止气象卫星星数据，采用地表温度日变化数据、叶面积指数、地表反照率，引入土壤属性、土壤水分，构建了两种裸土状况下地表土壤热通量日变化估算模型。其次，通过分析植被冠层对太阳短波辐射的消减作用过程以及冠层对土壤表面温度变化相位的影响，给出了地表温度变化与地表土壤热通量之间的相位差的关系，该相位差与植被的覆盖度存在线性关系，即相位(Δt)等于1.8倍的植被覆盖度。考虑植被冠层对土壤表面温度变化相位差以及引入土壤属性信息，改进获得了植被覆盖状况下两种地表土壤热通量日变化估算模型。最后基于日地表土壤热通量与日净辐射之间的变化关系，构建了基于日净辐射与植被覆盖度的日地表土壤热通量的经验估算方法，且完成了构建的植被覆盖状况下的地表土壤热通量遥感模型精度评价。本研究弥补地表土壤热通量日变化研究的不足，提高了植被覆盖状况下区域日尺度地表土壤热通量估算精度，进而提高能量平衡闭合率与可提高地表蒸散发遥感估算精度，可为水循环研究、水文过程、陆-气交互模式等研究提供技术与数据支撑。