Evaluation of Surface Shortwave Flux Estimates from GOES: Sensitivity to Sensor Calibration

Abstract

Parameters derived from satellite observations depend on the quality of the calibration method applied to the raw satellite radiance measurements. This study investigates the sensitivity of absolute reflectance, derived cloud cover, and estimated surface shortwave (SW) downward fluxes to two different calibration methods for the visible sensor aboard the eighth Geostationary Operational Environmental Satellite (GOES-8). The first method was developed at NOAA's National Environmental Satellite, Data, and Information Service (NESDIS), and the second at the NASA Langley Research Center. Differences in visible reflectance ranged from ?0.5% to 3%. The average difference in monthly mean cloud amount was ?3%, and the average difference in monthly mean shortwave downward flux was 5 W m?2. Differences in bias and rms of the SW fluxes when evaluated against ground station measurements were less than 3 W m?2. Neither calibration method was shown to consistently outperform the other. This evaluation yields an estimate of the errors in fluxes that can be attributed to calibration.