Velocities and Temperatures of Jupiter's Great Red Spot and the New Red Oval and Their Implications for Global Climate Change

Between 1998 and 2000 three White Ovals near 34oS merged and formed a new Oval. Initially, it was white, like its progenitors, but it turned brown and then red in 2005. The significance of the color changes are unknown but may be due to altitude or velocity changes of the new Red Oval (RO). Because the colors changed approximately one thermal time, or 7 years, after the mergers, the changes may indicate the global climate change that was predicted to occur after the mergers (based on the assumption that the chaotic mixing of heat due to the oscillatory motions of the White Ovals ceased after their mergers, so that latitudes near 34oS became barriers to meridional heat transport.) We observed both the RO and the Great Red Spot (GRS), with the HST ACS camera in April 2006 and with AO in the IR with Keck in July 2006. Vertical thermal structure was inferred from velocity measurements (derived from cloud displacements) that have uncertainties as small as 4ms-1, despite the blurring in our resolution of 5 pixels or 300km. In contrast, velocity uncertainties of the GRS and White Oval BC derived from high resolution Voyager mosaics were 7.5ms-1. We report differences in aspect ratios, areas and peak velocities of the GRS and the Oval(s) from 1979, 2000, and 2006. Some changes are large, and we discuss their implications for Jovian climate. We compare the areas of the clouds associated with the vortices with the areas enclosed by their outermost closed streamlines, and with the areas of the vortices’ potential vorticity anomalies. Indicators of climate change, such as changes in the mean zonal flow, the vertical stratification and vorticity gradients across the jet stream, are discussed.

This work was supported by NASA NNG06GA09G, HST and CFAO.