Galileo Imaging of Jupiter's Atmosphere: The Great Red Spot, Equatorial Region, and White Ovals

Abstract

During the first six orbits of the Galileo spacecraft's prime mission, the Solid State Imaging (SSI) system acquired multispectral image mosaics of Jupiter's Great Red Spot, an equatorial belt/zone boundary, a "5-μm hot spot" similar to the Galileo Probe entry site, and two of the classic White Ovals. We present mosaics of each region, approximating their appearance at visible wavelengths and showing cloud height and opacity variations. The local wind field is derived by tracking cloud motions between multiple observations of each region with time separations of roughly 1 and 10 hr. Vertical cloud structure is derived in a companion paper by Banfieldet al. (Icarus135, 230–250). Galileo's brief, high-resolution observations complement Earth-based and Voyager studies and offer local meteorological context for the Galileo Probe results. Our results show that the dynamics of the zonal jets and large vortices have changed little since Voyager, with a few exceptions. We detect a cyclonic current within the center of the predominantly anticyclonic Great Red Spot. The zonal velocity difference between 0° S and 6° S has increased by 20 m sec^(−1). We measure a strong northeast flow approaching the hot spot. This flow indicates either massive horizontal convergence or the presence of a large anticyclonic vortex southeast of the hot spot. The current compact arrangement of two White Ovals and a cyclonic structure greatly perturbs the zonal jets in that region.

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