Program: GN-2012B-Q-121

We propose NIRI observations of Uranus with filters that can vertically locate discrete cloud features and cloud band spatial variations with high S/N imaging that can identify many more cloud features than previously observed. This will allow us to build a two-dimensional map of discrete cloud pressures as well as track cloud motions in regions previously undersampled or not visible. This will constrain models of cloud composition and of the mixing ratios of parent gases. It will also constrain models of meridional circulation cells by locating regions of upwelling motions. Of particular interest is the northern high latitude regions coming into better view. In the south methane is depleted in the upper troposphere, which should inhibit convection if the depletion is due to downwelling motions. The failure to detect discrete cloud features supports that model. Observations in the north polar regions will define whether there is currently a large seasonal asymmetry.