The visible bands of ammonia - Band strengths, curves of growth, and the spatial distribution of ammonia on Jupiter

Abstract

We report room-temperature laboratory studies of the 5520 A (6..nu../sub 1/) and 6475 A (5..nu../sub 1/) bands of self-broadened ammonia at column densities ranging from 1.7--435.7 meter-amagats (m-am). Detailed equivalent-width measurements at 24 different pressure-pathlength combinations corresponding to four pressures between 44 and 689 torr and pathlengths between 32 and 512 m are used to determin curves of growth and integrated band strengths. The band strengths for the 6..nu../sub 1/ and 5..nu../sub 1/ overtones are 5520 A: S=0.096 +- 0.005 cm/sup -1/(m-am)/sup -1/ and 6475 A: S=0.63 +- 0.03 cm/sup -1/(m-am)/sup -1/, respectively.Using these band strengths and curves of growth, we analyze new spatially resolved spectra of Jupiter showing a nonhomogeneous distribution of ammonia in the Jovian atmosphere. The observed variations in the CH/sub 4//NH/sub 3/ mixing ratio are interpreted as evidence of altitude-dependent depletion of ammonia in the atmosphere.