Aerosol radiative corrections to the retrieval of sea surface temperatures from infrared radiances measured by the Advanced Very High Resolution Radiometer (AVHRR)

Abstract

Abstract The radiative effects of atmospheric aerosols on the retrieval of sea surface temperature from the infrared radiances measured in Channels 3(∼ 3·55−3·95µm), 4(∼ 10·30−11·30µm), and 5(∼ 11·50−12·50µm) of the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA polar-orbiting operational environmental satellites have been simulated in realistic models of a turbid atmosphere above the sea surface at a given temperature. The LOWTRAN-7 radiative transfer code has been used to compute the upwelling radiances at the central wavenumbers of these three channels. Brightness temperatures computed from these radiances were used in the NOAA/ NESDIS Multichannel Sea Surface Temperature (MCSST) retrieval algorithms to calculate sea surface temperatures. It is observed that the calculated (retrieved) sea surface temperatures are always less than the prescribed value in the model atmosphere, with the depressions ranging up to 4°C, depending upon the type and total columnar abundance of aerosols, prescribed sea surface temperature, and the satellite zenith angle of observation. The modelled sea surface temperature depressions show a high degree of correlation with the line-of-sight aerosol optical thickness; linear regression yields values in excess of 0·8 for the coefficient of determination.