DYNAMICS OF THE JOVIAN ATMOSPHERE:VOYAGER INFRARED OBSERVATIONS AND DIAGNOSTIC WAVE THEORY

[摘要] Voyager IRIS measurements on Jupiter show substantial vertical and horizontal structure which I apply to an assessment of the associated global scale dynamics. The retrieved temperature profiles indicate a variation of static stability between 4 x 10('8) cm('2)s('-2) and 2 x 10('9) cm('2)s('-2) from upper tropospheric ((TURN) 365 mb) to stratospheric ((TURN) 20 mb) levels. Meridional cross sections of the thermal deviations from both the zonal and global (area-weighted) means show a coherent organization on the scale of the belt-zone spacing. The computed zonal thermal wind shear between 100 and 300 mb is strongly correlated with the imaging measurements of the zonal flow and in the sense required to significantly reduce the strength of the observed jet streams over some 2-6 scale heights above the cloud deck. I compute the available potential energy reservoirs for the upper troposphere and show that these also vary with latitude in proportion to the kinetic energy reservoirs inferred from imaging measurements. Both the available potential energy and the eddy kinetic energy reservoirs are, however, more than a decade smaller than the estimated zonal mean kinetic energy.I review the observational evidence and constraints for possible planetary wave propagation in Jupiter's upper atmosphere from Voyager IRIS, radio occultation, and imaging measurements. I then apply the dispersion relations for planetary waves on an equatorial beta plane to a diagnostic assessment of the observed vertical and longitudinal scales. Although no single wave mode can be unequivocally identified, the lower order equatorial Rossby modes with an equivalent depth of h(, )<(, )2 km are most easily related to all the observations of features with a zonal planetary wavenumber n (LESSTHEQ) 20. The Kelvin and inertia-gravity modes with h(, )<(, )0.1 km are also acceptable solutions for a more restricted range of observations. If the wave interpretation is correct, unstable growth estimates consistent with the radio occultation profiles imply strong forcing at or below the tropopause.

[发布机构] Rice University

[效力级别] sciences