Radiative balance and dynamics in the stratosphere of Jupiter: Results from a latitude-dependent aerosol heating model

An updated dynamical model for the circulation in the jovian stratosphere has been developed, For computation of the heating and cooling rates in the stratosphere, required to obtain the radiative flux convergence, the model makes use of exponential-sum derived coefficients from laboratory and correlated-k distributions from line listing data for the various atmospheric gases. The aerosol distribution at different latitudes was determined from comparisons of results from microphysical models and near-UV jovian images obtained by the Wide Field and Planetary Camera 2 on the Hubble Space Telescope. The largest aerosol content is found at latitudes south of 65 degrees S planetographic, the aerosols being produced at higher atmospheric levels and at higher rates than those at the corresponding northern latitudes. At midlatitudes, the aerosol production rate is less than about two orders of magnitude than that found at high latitudes. The distinct imaginary refractive index spectra of the aerosols found at the different latitudes reflect a compositional difference in the material being produced as a result of chemical reactions. This difference is evident in the shortest wavelength explored (lambda(eff) = 230 nm) between low to midlatitudes and the polar regions. The resulting heating rates are much higher in the stratosphere than those given by previous estimates. The corresponding radiative equilibrium temperatures are therefore hotter than previously reported, mainly above the 10-mbar level. A north-south asymmetry in the stratospheric aerosol distribution was found, which, in turn, produces a different pattern in the derived quantities from the dynamical model, In particular, the Eliassen-Palm flux divergence (epsilon) shows a different pattern when compared with that inferred by Conrath et al. (1990, Icarus 83, 255-281) and West et al. (1992, Icarus 100, 245-259), At the base of the stratosphere we inferred the same circulation pattern as found by Gierasch et al. (1986, Icarus 67, 456-483) and West et al. (1992) with upwelling over the zones and subsidence in belts, but with higher values in the magnitude of the vertical winds at low latitudes. (C) 1997 Academic Press.