Rapid technique to cross-calibrate satellite imager visible channels

Abstract

Rapid and accurate calibrations of satellite imager sensors are critical for remote sensing of surface, cloud and radiative properties. A post-launch technique has been developed to routinely cross calibrate and normalize the imager visible (VIS) channel on-board operational geostationary (GEO) and low-Earth-orbit (LEO) satellites. As a reference calibration source, this simple approach uses the self-calibrating sensor from the Tropical Rainfall Measuring Mission (TRMM) Visible Infrared Scanner (VIRS) to calibrate other GEO and LEO satellites. The VIRS sensors have been found to be a stable and reliable reference source. This technique uses VIRS to calibrate the eighth Geostationary Operational Environmental Satellite (GOES-8) VIS sensor using collocated data with similar viewing zenith, solar zenith, and relative azimuth angles. GOES-8 is then used as a transfer medium to cross calibrate other GEO and LEO satellites. Post-launch VIS (~0.65 µm) calibration coefficients for GOES-8, -9, -10, -12, Meteosat-7, -8, and NOAA-14 AVHRR satellites are presented. GOES-8 had a non-linear degradation rate of 11% the first year of operational service and 4% in last year before it was decommissioned. GOES-9 degraded linearly at 7.9% per year during 1995-1998. GOES-10 degraded 12% the first year and 1.6% less each year after that. GOES-12 degraded 6% per year. The VIRS visible channel calibration is in good agreement with the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on-board the Terra and Aqua satellites supporting its use as a reference.