The use of infra red radiometers at sea and the development of a methodology for the correction of space borne sea surface temperature measurements for the oceanic thermal skin effect

This work is concerned with the deployment of infra red radiometers at sea, particularly for the measurement of skin sea surface temperature (SSST) for study of the oceanic thermal skin effect and the validation of space borne along track scanning radiometer (ATSR) and advanced very high resolution radiometer (AVHRR) series of satellite instruments.A new radiometer called SOOSR has been constructed and its development is presented along with data from sea trials abroad the MV Val de Loire during SUDOFEX. These data show that the SOOSR performance is comparable with that of SISTeR, which is considered to be the marine infra red standard radiometer. These radiometers performed well in the marine environment and SSST was retrieved to an accuracy of <0.1K.Data from the SISTeR radiometer deployed on the RRS James Clark Ross during the ROSSA are presented here. These data are used to investigate the nature of the skin-bulk temperature difference and to evaluate current models and parameterisation of the oceanic thermal skin effect. The Saunders (1967) and Fairall (1996) models gave comparable performances using the ROSSA data set and were able to estimate the skin-bulk temperature difference to within 0.1K.Radiometric SSST data from SUDOFEX have been compared with AVHRR SST product data and highlight the need to use skin rather than bulk SST based algorithms for performing the atmospheric correction of the SST radiance signals. A recommendation is made that radiometers, such as SOOSR or SISTeR, should be deployed frequently on fast moving ships to provide a large data set for the on going calibration and validation of space borne SST products. This will improve atmospheric transmission models by eliminating errors in the space borne AVHRR SST products that currently arise due to the thermal skin effect and the diurnal thermocline. In addition large skin-bulk SST data sets will then be available for the study of the ocean thermal skin for applications in climate research.