Properties, Changes, and Controls of Deep‐Convecting Clouds in Radiative‐Convective Equilibrium

Abstract

Abstract Changes in tropical high clouds associated with deep convection with warming are one of the largest sources of uncertainty in climate feedbacks. Here, we leverage an ensemble of models of many types in an idealized configuration to investigate how and why high clouds change the way they do. We find that deep‐convecting anvils, independent of how cloud fraction is defined, increase in height, increase slightly in temperature, and (generally) decrease in cloud fraction with warming sea surface temperature (SST). The controls on anvil height and temperature have well established physical reasoning, but the response of anvil cloud fraction to warming is more variable across studies and not as well understood. We test a previously published hypothesis for control of anvil coverage and find that, at least to first order, it is highly controlled by radiatively‐driven divergence, in which, with warming, anvil clouds occur in a more stable environment requiring less divergence to balance radiative cooling and, therefore, decreasing cloud coverage. We also find mid‐level clouds robustly decrease in coverage with warming SST and can be represented by a diagnostic scaling which attributes the robust decrease in mid‐level clouds to the rapid increase in the overall convective heating of the clouds compared to the much slower increase in the integrated radiative cooling rate. The robust response of deep‐convective clouds to warming and support for the underlying physical mechanisms across the spectrum of models, with both explicit and parameterized convection, increases confidence in their contribution to climate feedbacks.

Keywords

• radiative‐convective equilibrium
• convecting clouds
• idealized modeling
• RCEMIP