Convection and its transition from shallow to deep are ubiquitous processes that occur continuously in time and space. Despite this, the conventional approach of employing separate convection parameterizations (i.e., distinct shallow and deep convection schemes) still prevails. Recent advancements in unified boundary layer turbulence and moist convection parameterizations have shown promising results in accurately representing all convection types, with the potential to reduce uncertainties associated with parameterized convection in global circulation models.

To harness these benefits, we extended the simplified-higher-order-closure-mass-flux (SHOC+MF) turbulence and shallow convection scheme to encompass deep convection. The SHOC+MF scheme was initially developed to enhance the representation of low clouds in the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM). While SCREAM’s target resolution is 3.25 km, and some deep convection is explicitly resolved at this scale, adopting a unified convection scheme that can handle deep convection offers several advantages, including (i) facilitating a seamless transition from shallow to deep convection, and (ii) enabling SCREAM to run at coarser horizontal resolutions, thereby enhancing its overall robustness.

In the new version of the SHOC+MF scheme, the MF updrafts are coupled to a warm-, mixed-, and ice-phase microphysics framework that allows for water phase changes, and precipitation formation and evaporation within the updrafts. We evaluated the performance of SHOC+MF by analyzing its representation of the diurnal cycle of precipitating convection over land, focusing specifically on the Large-Scale Biosphere–Atmosphere (LBA) case within the doubly periodic SCREAM (DP-SCREAM) configuration. Our results demonstrate that SHOC+MF improves upon the default SCREAM’s scheme by capturing a realistic transition from shallow to deep convection. Additionally, we present preliminary numerical convergence testing results concerning horizontal grid resolution and time-step, which provide valuable insights into the scheme's reliability and robustness.