The exploitation of accurate satellite-based retrievals of SST for climate research offers many benefits. However, infrared instruments are sensitive to the ocean's radiative skin temperature, which can be significantly different from the temperature recorded by the in situ measurements of bulk SST traditionally used in climate analyses. These differences result from two important ocean surface phenomena, the skin effect and the diurnal thermocline. For comparison of remotely-sensed and directly-sampled SST data, potential differences arising from physical processes must be quantified.

A published model for the ocean skin effect has been validated using ship-based measurements of skin and bulk SST, and then applied to satellite data from the Along-Track Scanning Radiometer instruments. Temperature differences between night time (A)ATSR skin SST retrievals and collocated observations of bulk SST from buoys have been successfully predicted.

Diurnal thermocline development has been studied using observed differences between day time and night time SSTs from AVHRR data over the Mediterranean region. Estimates of heat fluxes and wind speeds from local dawn to the day observation time have been obtained from Met Office NWP analyses for each observed SST. Predictions of diurnal warming from published models forced by these flux data are compared to the observations, and reasons for variability in performance are explored.