Response of convection to relative SST : Cloud - resolving 1 simulations in 2 D and 3

3 The properties of equilibrated tropical convection are studied using a cloud-resolving model 4 with large-scale dynamics parameterized by the weak temperature gradient (WTG) 5 approximation. Model integrations are carried out in both two-dimensional (2D) and three-6 dimensional (3D) geometries. The target profile towards which horizontal mean free 7 tropospheric temperature is relaxed is held fixed while SST is varied. Consistent with previous 8 studies, large-scale ascent and precipitation increase under WTG as the SST is increased, but 9 more rapidly in 2D than 3D. This is related to greater extremes of near-surface buoyancy in 2D 10 as well as a lower gross moist stability, and perhaps also to weaker entrainment. In both 2D and 11 3D, the vertical profiles of large-scale vertical velocity are top-heavy and remarkably self-similar 12 in shape as SST is increased. When all integrations are analyzed together, precipitation increases 13 with column-integrated relative humidity once the latter reaches a threshold, as in observations 14 and other models. However, within each integration, the two quantities are correlated negatively, 15 albeit over a very narrow range.