Investigating the Along-Track Scanning Radiometer´s sea surface temperature precision

The Along-Track Scanning Radiometer (ATSR), flying on ESA´s first remote sensing satellite, ERS-1, has been designed to retrieve sea surface temperature (SST) to a precision of <0.25 K, which is more than twice the accuracy of any previously flown radiometer. In a recent global validation study against drifting buoys, Harris et al. achieve an ATSR SST precision of just 0.25 K using a retrieval algorithm incorporating only the 3.7 μm and 11 μm nadir view channels with spatially averaged (½°×½° in latitude and longitude) 1 km data. The present authors now extend this study to investigate whether this precision may be further improved by using straight 1 km match-up retrievals. Sub-pixel cloud and noise contamination of the standard ATSR dual-view SST product are two factors affecting the 1 km precision. They find that screening of the subpixel cloud improves the 1 km retrieval precision from 0.33 to 0.26 K, and that the instrumental noise contamination of the standard SST product can be effectively removed by smoothing the atmospheric correction over a matrix of 19×19 pixels