Abstract
Previous work has found that as the surface warms the large-scale
tropical circulations weaken, convective anvil cloud fraction decreases,
and atmospheric static stability increases. Circulation changes
inevitably lead to changes in the humidity and cloud fields which
influence the surface energetics. The exchange of mass between the
boundary layer and the midtroposphere has also been shown to weaken in
global climate models. What has remained less clear is how robust these
changes in the circulation are to different representations of
convection, clouds, and microphysics in numerical models. We use
simulations from the Radiative‐Convective Equilibrium Model
Intercomparison Project (RCEMIP) to investigate the interaction between
overturning circulations, surface temperature, and atmospheric moisture.
We analyze the underlying mechanisms of these relationships using a
21-member model ensemble that includes both general circulation models
and cloud resolving models. We find a large spread in the change of
intensity of the overturning circulation. Both the range of the
circulation intensity, and its change with warming can be explained by
the range of the mean upward vertical velocity. There is also a
consistent decrease in the exchange of mass between the boundary layer
and the midtroposphere. However, the magnitude of the decrease varies
substantially due to the range of responses in both mean precipitation
and mean precipitable water. This work implies that despite well
understood thermodynamic constraints, there is still a considerable
ability for the cloud fields and the precipitation efficiency to drive a
substantial range of tropical convective responses to warming.