Clear-sky and surface narrowband albedo variations derived from VIRS and MODIS Data
Yan Chen, SAIC, Hampton, VA; and S. Sun-Mack, R. F. Arduini, and P. Minnis
Satellite remote sensing of clouds requires an accurate estimate of the clear-sky reflectance for a given scene for detecting clouds and aerosols and for retrieving their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the visible (VIS; 0.63 Ám) and near-infrared (NIR; 1.6 or 2.13 Ám) channels available on same satellites as the CERES scanners. Another channel often used for cloud and aerosol, and vegetation cover retrievals is the vegetation (VEG; 0.86-Ám) channel that has been available on the Advanced Very High Resolution Radiometer (AVHRR) for many years. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. This paper presents a complete analysis of the CERES spectral clear-sky reflectances to determine the variations in clear-sky top-of-atmosphere (TOA) albedos for both snow-free and snow-covered surfaces for four spectral channels on MODIS using 5 and 3 years of Terra and Aqua data, respectively, and 3 years of data from two channels on the TRMM VIRS instrument. The surface albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. The results should be valuable for improved cloud retrievals and for modeling radiation fields.
Extended Abstract (664K)
Session 5, Observations and Modeling of the Surface Radiative Properties
Tuesday, 11 July 2006, 8:30 AM-10:00 AM, Hall of Ideas G-J
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