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 the subject is presented, along with a survey of the different techniques employed for obtaining SST from space measurements. The discussion concentrates on the advanced very high resolution radiometer (AVHRR) and similar instruments, as these are found to provide the most useful data for SST estimation. A comparison of different algorithms for deriving SST from the AVHRR instruments shows that there has been little improvement 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 coefficients dependent on the variances of the satellite brightness temperature images are found to be difficult to apply to real satellite data. Other new algorithms that include measurements of total atmospheric water vapor column may give a slight improvement in derivation accuracy, but they do not account for anomalous vertical structure in the atmosphere. Directions for future research to improve the accuracy of satellite-derived SST are suggested.