An Assessment of Representing Land‐Ocean Heterogeneity via CAPE Relaxation Timescale in the Community Atmospheric Model 6 (CAM6)

Abstract The time needed by deep convection to bring the atmosphere back to equilibrium is called convective adjustment timescale or simply adjustment timescale, typically denoted by . In the Community Atmospheric Model|Community Atmosphere Model (CAM), is the convective available potential energy (CAPE) relaxation timescale and is 1 hr, worldwide. Observational evidence suggests that is generally longer than 1 hr. Further, continental and oceanic convection are different in terms of the vigor of updrafts and can have different longevities. So using hour worldwide in CAM has two potential caveats. A longer improves the simulation of the mean climate. However, it does not address the land‐ocean heterogeneity of atmospheric deep convection. We investigate the prescription of two different CAPE relaxation timescales for land ( hr) and ocean ( to 4 hr). It is arguably an extremely crude parameterization of boundary layer control on atmospheric convection. We contrast a suite of 5‐year‐long simulations with two different for land and ocean to having one globally. The choice of longer over ocean is guided by previous studies and inspired by observational pieces of evidence. Nonetheless, to complement our variable experiments, we perform a simulation with hr and hrs. Most importantly, our key findings are immune to the exact values of prescribed and . The CAM model, with two values , improves convective‐stratiform rainfall partitioning and the Madden–Julian oscillation propagation characteristics.