SPECTRAL PARAMETERS OF SELF-BROADENED AND HYDROGEN-BROADENED METHANE FROM 2000 CM(-1) TO 9500 CM(-1) FOR REMOTE SOUNDING OF THE ATMOSPHERE OF JUPITER

Long-pathlength self- and H-2-broadened absorption spectra of CH4 have been recorded from 2000 to 9500 cm-1 at a resolution of 0.25 cm-1. These spectra were obtained for a wide range of conditions relevant to the atmosphere of Jupiter, including nominal temperatures of 190, 240, and 296 K, pathlengths from 64 to 512 m, and pressures from 0.2 to 700 torr, giving CH4 column abundances from 0.016 to 530 m-amagat. A series of molecular band models were fitted to these spectra at 10 cm - 1 resolution, showing that the Goody and Malkmus random band models with the Voigt lineshape provided the best fits to the data. The Goody-Voigt model was subsequently used to calculate the level in the Jovian atmosphere that will be sounded by observations of CH4 absorption, and estimates were made of the accuracy to be expected if this model were used to retrieve atmospheric parameters.