Modeling of Thin-Cloud TOA Reflectance Using Empirical Relationships and Two Landsat-8 Visible Band Data

Clouds are a common barrier of satellite optical images and adversely affect applications of remotely sensed optical data sets. The optical thickness of clouds varies spatiotemporally. The thickness can be very thin making the detection of thin clouds difficult. A new cirrus band (Band-9) of Landsat-8 has been added to detect thin clouds. However, the majority of spaceborne optical sensors existed previously or in operation do not have the cirrus band. An algorithm is developed to detect thin clouds without using a cirrus band. In particular, the top-of-atmosphere reflectance of thin clouds is modeled using the empirical relationships of the deep blue and blue bands of Landsat-8 Operational Land Imager. A Landsat-8 image of path 14/row 36 near southeastern North Carolina, USA, is used to validate the algorithm. Thin clouds are well-identified when compared to Landsat-8 Band-9 data. The spatial correlation coefficient for both is 93.49%. Therefore, the algorithm is valid. The algorithm is further verified when a blue band and a green band are used to develop the algorithm. Thus, the analytical approach should be extendible to Landsats 4, 5, and 7 sensors or optical sensors as long as they have a blue band and a green band. Finally, the applicability of the algorithm under various atmospheric conditions is verified after analyzing two water vapor absorption spectral bands of NASA/JPL Airborne Visible/Infrared Imaging Spectrometer data.