TOWARDS A LOCAL SPLIT WINDOW METHOD OVER LAND SURFACES
TOWARDS A LOCAL SPLIT WINDOW METHOD OVER LAND SURFACES
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DOI：
10.1080/01431169008955028
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发表时间：
1990-03-01
影响因子：
3.4
通讯作者：
LI, ZL
中科院分区：
文献类型：
--
作者：
BECKER, F;LI, ZL
分裂窗方法已成功地应用于由晴空卫星辐射率反演海面温度，具有简单易行的优点。然而，这种方法在陆地表面上不起作用，主要是因为发射率不等于1并且取决于通道。本文提出了一种将这种方法推广到陆地表面的方法，这种方法需要考虑发射率。首先，使用Lowtran 6，导致分裂窗口的辐射传输方程的各种线性化的精度进行检查。这意味着反演的地表温度线性依赖于发射率和亮温。这种行为已经在实际例子中得到了检验。理论方程推导表明，实际的表面温度可以再次表示为在两个相邻的通道与系数取决于光谱发射率，但不是在大气条件下测量的亮度温度的线性组合。使用Lowtran 6这些属性已被验证，这些系数的依赖性已被明确计算导致NOAA-9高级甚高分辨率辐射计的局部分裂窗口方法。最后，我们表明，准确的表面温度可以检索使用这种本地分裂窗口方法，一旦在两个相邻的通道发射率是已知的，具有足够的精度。
The split window method is successfully being used to retrieve the temperature over sea surfaces from satellite radiances in clear sky and has the great advantage of simplicity. However, such a method does not work over land surfaces, mainly because the emissivity is not equal to 1 and depends on the channel. An extension of this method to apply to land surfaces requires one to take account of emissivity—such an extension is presented in this paper. First, using Lowtran 6, the accuracies of the various linearizations of the radiative transfer equation leading to the split window are checked. This implies that the retrieved surface temperature depends linearly on emissivities and brightness temperatures. Such behaviour has been checked on actual examples. Theoretical equations are then derived which show that the actual surface temperature can again be expressed as a linear combination of the brightness temperatures measured in two adjacent channels with coefficients depending on spectral emissivities but not on atmospheric conditions. Using Lowtran 6 these properties have been verified and the dependence of these coefficients has been explicitly computed leading to a local split window method for the NOAA-9 Advanced Very High Resolution Radiometer. Finally, we show that accurate surface temperatures can be retrieved using this local split window method once emissivities in two adjacent channels are known with sufficient accuracy.