Response of convection to relative sea surface temperature: Cloud‐resolving simulations in two and three dimensions

[1] 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 performed in both 2‐D and 3‐D geometries. The target profile toward which horizontal mean free tropospheric temperature is relaxed is held fixed, while sea surface temperature (SST) is varied. Consistent with previous studies, large‐scale ascent and precipitation increase under WTG as the SST is increased, but more rapidly in two dimensions than in three dimensions. This is related to greater extremes of near‐surface buoyancy in two dimensions as well as a lower gross moist stability, and perhaps also to weaker entrainment. In both two and three dimensions, 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.