J. Geophys. Res., 116, D11119, doi:10.1029/2010JD015347.
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY.
Adam H. Sobel
Department of Applied Physics and Applied Mathematics, Department of Earth and Environmental Sciences, and Lamont-Doherty Earth Observatory, Columbia University, New York, NY.
The properties of equilibrated tropical convection are studied using a cloud resolving model with large-scale dynamics parameterized by the weak temperature gradient (WTG) approximation. Model integrations are carried out in both two-dimensional (2D) and three-dimensional (3D) geometries. The target profile towards which horizontal mean free tropospheric temperature is relaxed is held fixed while SST is varied. Consistent with previous studies, large scale ascent and precipitation increase under WTG as the SST is increased, but more rapidly in 2D than 3D. This is related to greater extremes of near-surface buoyancy in 2D as well as a lower gross moist stability, and perhaps also to weaker entrainment. The vertical profiles of large-scale vertical velocity are top-heavy and remarkably self-similar in shape as SST is increased. When all integrations are analyzed together, precipitation increases with column-integrated relative humidity once the latter reaches a threshold, as in observations and other models. However, within each integration the two quantities are correlated negatively, albeit over a very narrow range.