Observations of Three-Dimensional Radiative Effects that Influence MODIS Cloud Optical Thickness Retrievals
Observations of Three-Dimensional Radiative Effects that Influence MODIS Cloud Optical Thickness Retrievals
复制标题
影响MODIS云光厚反演的三维辐射效应观测
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
A. Marshak
中科院分区：
文献类型：
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作者：
T. Várnai;A. Marshak
摘要当从卫星观测中检索云的特性时，目前的计算将一维（1D）理论应用于三维（3D）世界：它们只考虑垂直过程，忽略水平相互作用。本文提出了一种新的方法，估计云光学厚度反演的三维效果。所提出的方法结合可见光和热红外图像，看看是否三维辐射效应使云出现不对称，也就是说，是否云表面倾斜朝向太阳系统比表面倾斜远离it.The观察到的不对称，然后使用估计3D效果为1公里大小的像素，以及50公里大小的地区。中分辨率成像光谱仪（MODIS）图像获得的初步结果表明，3D效应造成丰富的不确定性在1公里分辨率的一维检索。对50公里乘50公里的区域进行平均可以大大减少误差，但不能完全消除误差。保守估计显示，M…
Abstract When cloud properties are retrieved from satellite observations, current calculations apply one-dimensional (1D) theory to the three-dimensional (3D) world: they consider only vertical processes and ignore horizontal interactions. This paper proposes a novel approach that estimates 3D effects in cloud optical thickness retrievals. The proposed method combines visible and thermal infrared images to see whether 3D radiative effects make clouds appear asymmetric—that is, whether cloud surfaces tilted toward the sun are systematically brighter than surfaces tilted away from it. The observed asymmetries are then used to estimate 3D effects for 1-km-size pixels as well as 50-km-size areas. Initial results obtained for Moderate-Resolution Imaging Spectroradiometer (MODIS) images reveal that 3D effects cause abundant uncertainties in the 1-km-resolution 1D retrievals. Averaging over 50 km by 50 km areas greatly reduces the errors but does not remove them completely. Conservative estimates show that the m...