Validation of MODIS and AVHRR/3 sea surface temperature retrieval algorithms

Sea surface temperature (SST) is one of the main factors in the understanding of the interaction between the oceans and the atmosphere, so the development of algorithms for the production of reliable SST data sets from space borne infrared radiometers has been pursued since late 1960´s. Unfortunately the thermal structure in the upper 10 m of the ocean is complex and highly variable, so SST may be significantly different depending on the vertical depth of the in situ measurement, the local time of day, local conditions at the air-sea interface and the instrument used. In this context, the validation of the AVHRR/3 and MODIS atmospheric correction algorithms for the retrieval of sea surface temperature from the Canary Islands-Azores-Gibraltar area is performed by using in situ temperature measurements, derived from the ARGO data collection system and by the oceanographic service of the University of Las Palmas Gran Canaria, over the period from December 2000 to September 2003. The improvements and restrictions introduced in the systematic procedure to generate the match-up database have lead to a very high quality comparison data set. Finally, error analysis shows that SST can be retrieved with accuracies better than 0.6degC and, specifically, the MODIS mid-infrared algorithm achieves an excellent performance at night-time with accuracies to the order of 0.35degC