H2 spectroscopy and a diurnally changing cloud on Jupiter

Abstract

Spectroscopic observations of H2 in specific longitude regions of Jupiter as they rotate from limb to limb are reported. Data obtained in the 3-0 S(0) and S(1) lines using a CCD detector and a spectrograph with either echelle or plane gratings at the Cassegrain focus of the 24-inch telescope at Whipple Observatory during April-June 1983 are presented in extensive tables and graphs and analyzed in detail, modeling spatial and temporal variations at seven latitudes. An east-to-west increase in the equivalent line widths is attributed to the combined action of internal and solar heating of a convective layer, resulting in diurnal changes in the vertical cloud structure. It is inferred that the hydrogen observed is mainly in an equilibrium thermodynamic state, with small amounts of nonequilibrium hydrogen at high altitudes.