SATELLITE-DERIVED SEA-SURFACE TEMPERATURES - CURRENT STATUS

The current status of techniques for deriving sea surface temperatures (SST) from infrared satellite data is reviewed. A short history of th e subject is presented, along with a survey of the different technique s employed for obtaining SST from space measurements. The discussion c oncentrates on the advanced very high resolution radiometer (AVHRR) an d similar instruments, as these are found to provide the most useful d ata for SST estimation. A comparison of different algorithms for deriv ing SST from the AVHRR instruments shows that there has been little im provement in derivation accuracy over the past decade. The importance of the ''first-guess'' principle is introduced and shows that some of the more recent ''advances'' in this field do not address the residual source of error in SST derivation. New algorithms that include coeffi cients dependent on the variances of the satellite brightness temperat ure images are found to be difficult to apply to real satellite data. Other new algorithms that include measurements of total atmospheric wa ter vapor column may give a slight improvement in derivation accuracy, but they do not account for anomalous vertical structure in the atmos phere. Directions for future research to improve the accuracy of satel lite-derived SST are suggested.