Sea-surface temperature (SST) observations are key in many aspects of meteorology and oceanography. For global coverage and measurement consistency, satellite data offer significant advantages over in situ observations. The Advanced Along-Track Scanning Radiometer (AATSR) was launched on board the European Envisat platform in March 2002. AATSR is the third in a series of similar infrared instruments: its primary purpose is the retrieval of SST at levels of accuracy suitable for climate research. By the end of the Envisat mission a 15-year record of global SST data will have been completed, spanning 1991-2007.

In this paper we present results from the first few months of AATSR data. ESA's near-real time Meteo product consists of channel brightness temperatures and a retrieved skin SST spatially averaged to 1/6° resolution. This product is obtained in near-real time at the Met Office, UK, where a skin SST retrieval and conversion to nominal bulk SST are performed. Initial validation of the new SST data includes comparisons against collocated buoy observations and an independent climate SST analysis. Our results confirm the reliability of the instrument and the benefit of including models for the ocean skin effect and diurnal thermocline in the Met Office processing system. A further comparison of SSTs derived from the ATSR-series against those from the TRMM Microwave Imager reveals some discrepancies, for which reasons will be explored.