ASSESSMENT OF CLOUD COVER CHARACTERISTICS OVER CALIBRATION TEST SITES USING MODIS CLOUD MASK PRODUCTS
Spaceborne remotely sensed data can provide the spatial, spectral, and temporal coverage for earth monitoring. Radiometric calibration is indispensable for the accurate higher level products derived from satellite optical sensors, and the long-term radiometric calibration has a crucial role. Especially, vicarious calibration is currently the most accurate method to conduct the radiometric calibration of satellite optical sensors. Various organization and projects have been conducting the vicarious calibration experiments for satellite optical sensors. Railroad valley playa is the most popular calibration site, and we have been also acquiring the vicarious calibration data for Terra ASTER there from the past. Recently, RadCalNet (Radiometric Calibration Network) is open to the public, which is an initiative of the CEOS WGCV. Railroad valley is also one of the RadCalNet sites, and our calibration site is located at the adjacent area. Understanding the cloud cover characteristics over calibration test sites is very important for vicarious calibration and automated facilities measurement. This research evaluates the clear sky ratio for Railroad valley playa using Terra an Aqua MODIS cloud mask product (MOD35_L2 and MYD35_L2) since 2000.