Improvements on the methodology to obtain accurate and automatic maps of sea surface temperature from NOAA-AVHRR data

The need for high accuracy in the measurement of sea surface temperature (SST) from space was recognized in the early stages of planning the World Climate Research Program. Improvements on the normally used methodologies to obtain accurate and automatic maps of SST in the Canary-Azores-Gibraltar area have been developed. Procedures applied to the images from the AVHRR sensor aboard NOAA 14 consists on: (i) a radiance-based nonlinearity correction method; (ii) an automatic procedure for the geometric correction, achieving accuracies to the order of the pixel; (iii) a qualitative and quantitative test between in situ SST measurements and nearly-coincident satellite observations, including an improved algorithm for the cloud detection. Coefficients to obtain the SST from the AVHRR data are estimated by regression analysis using co-located in situ and satellite measurements (matchups). Error analysis and validation test, using the AVHRR Pathfinder Oceans Matchup Database, has shown that SST can be retrieved to within 0.45°C RMSD