复杂地形区地表短波辐射估算及时空扩展研究

地表短波辐射是总辐射的主导因素，是整个地球系统物质与能量循环的主要驱动力，但是目前的全球辐射产品未充分考虑云和复杂地形的综合影响，且空间分辨率较粗，难以满足实际应用的需求。本项目在已建立的水平地表全天候短波辐射传输模型的基础上，综合考虑太阳-云-地-观测之间的几何关系，耦合地形因素，建立适合复杂地形区的全天候短波辐射传输模型，利用极轨卫星数据，实现复杂地形区高空间分辨率地表短波辐射分量估算；以此为基础，在区域尺度建立云覆盖度和地形统计因子耦合的参数化模型，寻找区域耦合模型估算短波辐射分量的最优空间尺度；结合极轨和静止卫星数据，在最优空间尺度实现1小时分辨率地表短波辐射分量的估算，提取地表短波辐射的日变化特征并进行时间扩展，得到日平均的复杂地表短波辐射；最后，结合计算机真实场景模拟和野外实验对所提出的复杂地表全天候短波辐射模型和反演算法进行综合验证。

Land surface shortwave radiation is the dominant factor of the surface radiation and the primary driving force of the earth system’s substance and energy cycles. However, the effects of cloud and complex topography haven’t been thoroughly considered in the current global radiation products. Besides, the spatial resolutions of these products are relatively coarse, therefore, they are difficult to meet the needs of applications in many fields. In order to explore these problems step by step, our project will contain the following parts: 1) On the basis of the previous shortwave radiative transfer model established for flat surface, shortwave radiative transfer models for rugged terrain under all sky conditions will be built by coupling the terrain factors with sun–cloud–surface–satellite geometry. The land surface shortwave radiation components with high spatial resolution will be retrieved over rugged terrain using polar orbit satellite data; 2) The parameterized model will be developed over the region scale by combining the cloud fraction cover and statistical terrain factors. The optimum scale of estimating shortwave radiation using this parameterized model will be analyzed; 3) Land surface shortwave radiation components will be estimated using both of the polar orbit and geostationary satellite data for each hour over the optimal spatial scale. The surface shortwave radiation components will be extrapolated throughout a whole day by analyzing their diurnal variation. The daily averaged surface shortwave radiation will be computed, which is more useful for many land process applications; 4) Finally, the proposed shortwave radiation models and inversion algorithms for rugged terrain will be validated under all sky conditions based on both of the three-dimensional real scene computer simulation and field campaigns.