Radiometric Validation of ERS-1 Along-Track Scanning Radiometer Average Sea Surface Temperature in the Atlantic Ocean

Abstract

The ERS-1 along-track scanning radiometer (ATSR) provides a half-degree latitude by half-degree longitude average sea surface temperature (ASST) measurement representative of the thermal skin layer of the ocean that is intended for use in global climate studies. Radiometric skin sea surface temperature (SSST) and bulk sea surface temperature (BSST) observations are presented that have been collected spatially coincident and near contemporaneously with ERS-1 ATSR ASST in the tropical and subtropical Atlantic Ocean during September 1992. Using these data the authors demonstrate that the ERS-1 ATSR ASST (SADIST 600) computed from both forward and nadir observations (dual ASST) has a cool bias of ?0.54 K, and the ASST computed from nadir-only observations has a bias of ?0.78 K. The rms scatter about the mean bias for the dual ASST is 0.18 K and for the nadir ASST is 0.22 K, demonstrating the effectiveness of the along-track scanning concept. The difference between SSST and BSST validation techniques is less than 0.05 K because high wind speeds dominate the in situ dataset, preventing an appreciable skin temperature deviation at the air?sea interface. Most of the bias described above can be explained by Saharan dust and aerosols from the Mount Hudson and Mount Pinatubo volcanic eruptions that were present in the atmosphere during the measurement period.