Sounding of Planetary Atmospheres: A Fourier Analysis of the Radiative Transfer Equation

Abstract

In order to determine the information content in the thermal profile of a planetary atmosphere observed by means of remote sensing techniques, Fourier analysis concepts and Shannon's sampling procedures are applied to the infrared data obtained. After examining the conditions under which the radiative transfer equation can be written in the form of a convolution integral, it is established that, in the presence of noise, the experimental and retrieved functions must be considered as having band-limited spectra. It is then possible to evaluate the amount of information which exists in the retrieved structure and to determine, as a function of the signal-to-noise ratios, the spectral resolution and number of measurements which preserve the information content. The results of the analysis are eventually applied to the sounding of the atmosphere of giant planets, taking into account the experimental conditions of the 1977 Mariner-jupiter-Saturn mission.