A simplified method to separate latent and sensible heat fluxes using remotely sensed data
A simplified method to separate latent and sensible heat fluxes using remotely sensed data
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DOI：
10.1109/igarss.2001.978294
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发表时间：
2001-07
期刊：
影响因子：
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通讯作者：
H. Su;Renhua Zhang;Xin-Zhai Tang;Xiao-Ming Sun;Zhilin Zhu;Zhen-min Liu
中科院分区：
文献类型：
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作者：
H. Su;Renhua Zhang;Xin-Zhai Tang;Xiao-Ming Sun;Zhilin Zhu;Zhen-min Liu
本文讨论了归一化植被指数（NDVI）与伪热惯量（AVHRR数据的昼夜地表温差）之间的关系。建立了一种简化的植被覆盖地表潜热通量和感热通量分离方法。地表反射率和地表温度之间的类似关系已经被一些关注和/或半干旱地区土壤蒸发区域估计的科学家所阐明。结果表明，该方法在反演土壤蒸发甚至传热阻力方面效果良好。伪热惯量与NDVI的散点图表明，高频点明显形成三角形，即高频点位于三角形内。三角形的上边可以写为：DT/sub u/（NDVI）=a/sub u/+B/sub u/*NDVI。类似地，其下侧可以表示为：DT/sub 1/（NDVI）=a/sub 1/+B/sub 1/*NDVI。然后，波文比B/sub i/可以表示为：B/sub i/=（DT/sub u/（NDVI/sub i/）-DT/sub i/）/（DT/sub u/（NDVI/sub i/）-DT/sub i/（NDVI/sub i/））-1，其中DT/sub i/是第i个像元的昼夜地表温度差，NDVI/sub i/也是。土壤热通量G是根据经验确定的。根据植被覆盖度将净辐射分解为土壤净辐射和植被净辐射，得到G=0.35* Rn/sub s/+0.05* Rn/sub v/，其中常数参数随土地覆盖和土地利用的不同而变化。
In this paper, the relationships between NDVI (normalized difference vegetation index) and pseudo thermal inertia (land surface temperature difference between day and night AVHRR data) are discussed. A simplified method was established to separate the latent and sensible heat fluxes on vegetation covered land surface. Analogous correlations between surface reflectance and LST (Land Surface Temperature) had been illustrated by several scientists who are concerned about regional estimation of soil evaporation in and or semi-arid areas. It proves work well in retrieving of soil evaporation or even aerodynamic resistance of beat transfer. The scattergram of pseudo thermal inertia versus NDVI demonstrates that higher frequency points clearly form a triangle shape, that is to say, the higher frequency points are within the triangle. The upper side of the triangle can be written as: DT/sub u/(NDVI)=a/sub u/+b/sub u/*NDVI. Similarly, the lower side of it can be denoted as: DT/sub l/(NDVI)=a/sub l/+b/sub l/*NDVI. Then, Bowen ratio B/sub i/ can be expressed as following: B/sub i/=(DT/sub u/(NDVI/sub i/)-DT/sub i/)/(DT/sub u/(NDVI/sub i/)-DT/sub l/(NDVI/sub i/))-1, where DT/sub i/ is the land surface temperature difference between day and night of the ith pixel, NDVI/sub i/ is as well. The soil heat flux G is determined empirically. After separating Rn (net radiation) into Rn/sub s/ and Rn/sub v/ (net radiation for soil and vegetation respectively) based on the vegetation fraction, the G can be obtained by: G=0.35* Rn/sub s/+0.05* Rn/sub v/, where the constant parameters may vary according to different land cover and land use.