Relationships between Clouds, Circulation, and Radiation in Long-Channel Radiative Convective Equilibrium Simulations

Idealised radiative equilibrium simulations have proved an invaluable tool for studying tropical convection. Using a long-channel configuration (i.e. a narrow yet long domain), simulations can be run with sufficiently high resolution to resolve convective scales over domains that are sufficiently large (in one direction) to resolve the large-scale circulation. These types of simulations are becoming increasingly widely used for studying the coupling between clouds and circulation, which remains a key driver of uncertainty for cloud feedbacks.

In this presentation, we describe long-channel radiative convective equilibrium simulations run with the UK Met Office Unified Model. These simulations are run for a variety of fixed sea surface temperature (SST) patterns, including SSTs fixed to a single value and SSTs that vary spatially in an approximation of observed SST gradients.

We detail the extent to which these simulations reproduce the observed large-scale circulation in the tropics and highlight low frequency oscillations that occur when there is an SST gradient both in our simulations and in other models. We investigate the causes and consequences of these oscillations. In the context of these results we present further analysis of the coupling between clouds and circulation in the simulations and how this coupling affects climate sensitivity.