Different from Neptune, where several dark spots (vortices) have been observed since 1989, the Uranian Dark Spot (UDS) was first observed with Hubble Space Telescope (HST) on Aug. 23, 2006 and again on Aug. 24, 2006. About 52 days later, the UDS may have again been observed by Sromovsky using the KECK observatories at Mauna Kea, Hawaii. Wind profiles from tracking the clouds on Uranus also showed changes during this same time period corresponding to the approach of spring in the northern hemisphere (Sromovsky, 2005) compared to previous zonal wind profiles like those of Smith, 1986 and Karkoschka, 1998. The newly dynamic atmosphere of Uranus is far more active than the early boring impression left by Voyager II, so this planet continues to attract numerous observations, permitting ongoing analysis of the UDS.

The appearance and the dynamics of the dark spot provide a chance to study features of the atmosphere of Uranus. Based on the data from the observations, we are applying Explicit Planetary Isentropic-Coordinate (EPIC) General Circulation Model (GCM) (Dowling, et al., 2006) to simulations of the dark spot and wind profile changes on Uranus. Our simulations are focused on the lifetime and dynamics of the dark spot and the overall sustainability of the feature in different background environments. The wind profile, the latitude, and the strength of the spot are the key parameters in our simulations. Furthermore, from a computational fluid dynamics point of view, the effects of resolution and scale are also studied. Current results indicate that the changing zonal wind profiles have created conditions more conducive for long-lived vortices at the observed latitudes compared to both earlier wind profiles and other current latitudes.