遥感混合像元日蒸散模型及应用研究

发布时间：2018-04-20 15:23

本文选题：遥感 + 蒸散　；参考：《中国科学院大学(中国科学院遥感与数字地球研究所)》2017年硕士论文

【摘要】：蒸散是水量平衡的主要分量,又是能量平衡的重要组成部分。遥感是目前公认的估算区域尺度蒸散的最有效方法。但是,下垫面的非均匀和时间尺度的扩展问题是遥感估算蒸散量研究的难点。论文针对下垫面地类的非均匀性造成的遥感混合像元,建立了适应不同尺度、不同数据源的非均匀地表蒸散模型;并将遥感观测到的瞬时地表蒸散量扩展到了日尺度,提高了模型的实际应用价值。论文首先根据蒸发比的含义和马赛克模型的思想,采用面积加权的思想,推导出了混合像元蒸发比的计算方法。在推导过程中,论文提出了两个关键假设:(1)混合像元中各亚像元的有效能在误差范围内大致相等,且等于混合像元的有效能;(2)将混合像元中地类的亚像元的蒸发比的值与该地类纯像元的蒸发比的值建立某种联系,从而使亚像元蒸发比可以被该地类纯像元的蒸发比的值代替。对于混合像元中亚像元蒸发比代表性的假设,论文利用遥感反演与站点实测数据相对比的方法,讨论了七种假设方案,最终根据数理基础和误差情况选定最邻近纯像元蒸发比来代替混合像元中亚像元地类的蒸发比。根据混合像元蒸发比计算公式,进一步推导出了混合像元蒸散量的估算方法,建立了混合像元日蒸散模型。同时,利用HJ1-B卫星采用先聚合再反演的方法,将30m分辨率的参数统一到地表温度参量的300m尺度,然后在此基础上进行水热通量反演。之后利用混合像元日蒸散模型对该结果进行尺度校正,并利用Hiwater(Heihe Watershed Allied Telemetry Experimental Research)非均匀下垫面多尺度蒸散发观测试验提供的涡度相关数据对结果进行验证,得到的结果相较于均匀地表假设的模型有一定的提高。
[Abstract]:Evapotranspiration is the main component of water balance and an important component of energy balance. Remote sensing is currently recognized as the most effective method for estimating evapotranspiration at regional scale. However, the inhomogeneity of underlying surface and the expansion of time scale are the difficulties in the estimation of evapotranspiration by remote sensing. In this paper, a heterogeneous evapotranspiration model for different scales and different data sources is established, and the instantaneous surface evapotranspiration observed by remote sensing is extended to a daily scale. The practical application value of the model is improved. Firstly, according to the meaning of evaporation ratio and the idea of mosaic model, the method of calculating the evaporation ratio of mixed pixel is deduced by using the area weighting idea. In the process of derivation, two key assumptions are put forward: 1) the effective efficiency of each sub-pixel in the mixed pixel is approximately equal in the error range. And the effective ratio is equal to the mixed pixel.) the value of the evaporation ratio of the subpixel of the ground class in the mixed pixel is related to the value of the evaporation ratio of the local pure pixel, so that the sub-pixel evaporation ratio can be replaced by the value of the evaporative ratio of the local pure pixel. For the representation hypothesis of the subpixel evaporation ratio of mixed pixels, this paper discusses seven hypothetical schemes by comparing remote sensing inversion with measured data. Finally, the nearest pure pixel evaporation ratio is selected according to the mathematical basis and error situation to replace the evaporation ratio of the subpixel ground class of the mixed pixel. Based on the formula of evaporative ratio of mixed pixel, the method of estimating the evapotranspiration of mixed pixel is derived, and the daily evapotranspiration model of mixed pixel is established. At the same time, by using HJ1-B satellite, the parameters of 30m resolution are unified to 300m scale of the surface temperature parameter by the method of first aggregation and then inversion, and then the water and heat flux inversion is carried out on this basis. Then the mixed pixel daily evapotranspiration model is used to calibrate the results, and the vorticity correlation data from the multi-scale evapotranspiration observation on the non-uniform underlying surface of Hiwater(Heihe Watershed Allied Telemetry Experimental research are used to verify the results. The obtained results are better than the model of uniform surface hypothesis.
【学位授予单位】：中国科学院大学(中国科学院遥感与数字地球研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP751

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