OBSERVATIONS AND NUMERICAL MODELING OF THE JOVIAN RIBBON

Multiple wavelength observations made by the Hubble Space Telescope in early 2007 show the presence of a wavy, high-contrast feature in Jupiter’s atmosphere near 30°N. The “Jovian Ribbon,” best seen at 410 nm, irregularly undulates in latitude and is time-variable in appearance. A meridional intensity gradient algorithm was applied to the observations to track the Ribbon’s contour. Spectral analysis of the contour revealed that the Ribbon’s structure is a combination of several wavenumbers ranging from k = 8–40. The Ribbon is a dynamic structure that has been observed to have spectral power for dominant wavenumbers which vary over a time period of one month. The presence of the Ribbon correlates with periods when the velocity of the westward jet at the same location is highest. We conducted numerical simulations to investigate the stability of westward jets of varying speed, vertical shear, and background static stability to different perturbations. A Ribbon-like morphology was best reproduced with a 35 ms−1 westward jet that decreases in amplitude for pressures greater than 700 hPa and a background static stability of N = 0.005 s−1 perturbed by heat pulses constrained to latitudes south of 30°N. Additionally, the simulated feature had wavenumbers that qualitatively matched observations and evolved throughout the simulation reproducing the Jovian Ribbon’s dynamic structure.

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