JOVIAN SYSTEM DATA ANALYSIS PROGRAM PROPOSAL SUMMARY

Groundbased monitoring of Jupiter at a wavelength of 5 microns in the thermal infrared by G.S. Orton and colleagues revealed that the Galileo probe entered at the edge of a 5-micron ``hot spot''. These hot spots are characterized primarily by a low abundance of the cloud particles that dominate the 5-micron opacity at other locations on the planet, and by significant dessication of ammonia, water, and hydrogen sulfide in the upper layers of the troposphere. The hot spots, located in a narrow latitude band centered on +6.5 degrees, are observed to occur with highest likelihood in 8 or 9 quasi-evenly-spaced longitudinal areas that drift with a rate that changes only slowly with time (Ortiz et al. 1998). The goals of this program are to i) determine how the hot spots differ in their temperature structure, vertical cloud structure, and cloud particle properties from other locations on the planet; ii) determine what aspects of the vertical opacity structure of the atmosphere in the hot spots allows them to be so bright at 5 microns, and iii) further develop a promising dynamical model for the hot spots that interprets their observed latitude, wavenumber and drift speed in terms of an equatorially trapped Rossby wave (Ortiz et al. 1998). Our work will be important for determining the extent to which probe measurements in a hot spot are likely to reflect conditions elsewhere on the planet. In the 2-year time frame of this program our focus will be to explore the effect of the large vertical shear of mean zonal wind measured by the probe on models of the equatorially trapped Rossby wave of Ortiz et al. (1998), and we will investigate whether the dynamics of this wave might engender some of the unusual characteristics of the hot spots. Previous work we have done on 5-micron hot spots includes the following:
G. Orton, et al. 1996. Science 272, 839-840.
G. S. Orton, et al. 1998. J. Geophys. Res., submitted.
J. L. Ortiz, et al. 1998. J. Geophys. Res., in press.
M. Roos-Serote, et al. 1998. J. Geophys. Res., in press.
B. Ragent, et al. 1998. J. Geophys. Res, in press.