Sensitivity analysis of remote sensing of sea surface temperature by one dimensional synthetic aperture microwave radiometer

Abstract

Compared with the traditional microwave radiometer, one dimensional synthetic aperture microwave radiometer can effectively improve the spatial resolution of sea surface temperature retrieval. However, the spaceborne one dimensional synthetic aperture microwave radiometer is multiple incidence angle observation for the sea target and the incidence angle changes from 0° to 55°. In order to develop sea surface temperature inversion algorithms suited to one dimensional synthetic aperture microwave radiometer, it is necessary to evaluate the sensitivities of brightness temperature to oceanic and atmospheric environmental elements. Using the sea surface emissivity model and the atmospheric radiative transfer model, we construct a oceanic and atmospheric radiative transfer mode suited to the one dimensional synthetic aperture microwave radiometer. In this paper, the sensitivity changes of C-band vertical and horizontal polarization brightness temperature to oceanic and atmospheric environmental elements at different incidence angles are studied, and the corresponding sensitivity coefficients are calculated. The results indicate that the sensitivities of vertical and horizontal polarization brightness temperature to oceanic and atmospheric environmental elements show different characteristics. With the increase of the incidence angle, the sensitivity of the vertical polarization brightness temperature to the sea surface temperature is enhanced, and the sensitivity to the sea surface wind field is relatively weakened; but the horizontal polarization brightness temperature is opposite. The vertical and horizontal polarization brightness temperature errors caused by the errors of atmospheric water vapor content and cloud liquid water content increase with the increasing of the incidence angle, however, even at a large incidence angle of 55°, the errors of vertical and horizontal polarization brightness temperature are still less than 0.12 K. If the accuracy of sea surface temperature inversion is higher than 1 K, the calibration precision of one dimensional synthetic aperture microwave radiometer should be better than 0.6 K. Overall, the results of this paper are of great significance to the research of sea surface temperature retrieval with multiple incidence angle for one dimensional synthetic aperture microwave radiometer.