Sea surface temperature (SST) is an important variable to better understand interactions between the oceans and the atmosphere. The optimum interpolation sea surface temperature (OISST) is one of the most popular SST products with a spatial grid resolution of 0.25° and a temporal resolution of 1 day. It is produced and maintained operationally at 1 day delay at the National Ocean and Atmospheric administration's (NOAA's) National Climate Data Center (NCDC). It has been widely used for climate monitoring and prediction, and model validation. This paper focuses on how we make the OISST operational and provide the data to the users at a daily basis.

The OISST is generated from several data sources including SST data from Advanced Very High Resolution Radiometer (AVHRR) and Advanced Microwave Scanning Radiometer (AMSR), sea-ice data, and in situ data from ships and buoys. The AVHRR data are processed by the U.S. NAVY Oceanographic Office and distribute by NOAA Environmental Satellite, Data, and Information Service (NESDIS). The AMSE data are from Remote Sensing Systems. The in situ SST data are obtained from the NOAA National Centers for Environmental Prediction (NCEP) real-time observations. The ice data are from NOAA NCEP.

The first step of OISST production is the quality control, which checks latitude and longitude, data duplication, and compares with the first guess and standard deviation. Then we calculate the super observation (bin-average of one instrument in one grid box) of each data set. Satellite data are corrected with respect to the in situ data. Finally the source data are merged to produce the OISST. The final products include daily SST, SST anomaly, estimated error standard deviation of analyzed SST, and sea ice concentration. The OISST is updated daily based on the real-time incoming source data. As the source data may have updates later the final OISST is recomputed after two weeks.

Users can obtain the OISST products via several channels: NCDC data server, NOMANDS LAS or TREDDES server and server of the Group for High-Resolution Sea Surface Temperature (GHRSST) at Jet Propulsion Laboratory (JPL).