Radiative–convective equilibrium (RCE) is a state of statistical equilibrium characterised by a balance between radiative cooling and convective heating. As a simple idealisation of the tropical atmosphere it has been widely used in both theoretical and modelling studies to investigate various aspects of the climate system. However, questions remain as to the relevance of RCE to the real atmosphere, particularly at small scales. Observations suggest that at the scale of a GCM grid box (~100 km) the atmosphere is very rarely in RCE; only on scales of several thousand kilometres is RCE observed a majority of the time. This points to potential limitations of the RCE framework for studying convection in small-domain cloud-resolving models (CRMs) or single-column models (SCMs). In addition, RCE implies zero net mass flux, making it a poor approximation for regions of organised tropical convection (such as the ITCZ) which are characterised by net ascent.

The present study proposes an extension to the recently instigated radiative–convective equilibrium model intercomparison project (RCEMIP), specifically designed for small-domain CRMs and SCMs. The proposed framework involves the inclusion of a simple profile of large-scale ascent (forcing), with simulations performed for a range of forcing amplitudes (0–5 cm/s) as well as for the three SSTs (295, 300, and 305 K) considered in RCEMIP. Here results from a preliminary sample of models will be presented to demonstrate the differences between the RCE and forced equilibrium states and highlight potential applications and future directions for the intercomparison.