Layer-Dependent Diurnal Moist Static Energy Biases in the Unified Forecast System and Their Role in MJO Preconditioning - A DYNAMO Case Study

not-yet-known not-yet-known not-yet-known unknown Accurate simulation of the Madden-Julian Oscillation (MJO) requires realistic diurnal evolution and vertical distribution of moist static energy (MSE). While prior studies have documented systematic MSE deficit in global models, vertically dependent physical processes responsible for these errors remain insufficiently understood. This study applies a hierarchical modeling and evaluation framework, combining fully coupled Unified Forecast System (UFS) forecast with observation-constrained single-column model (SCM) experiments, to enable vertically and diurnally resolved assessment of MSE during two MJO events from the DYNAMO field campaign. Results reveal a coherent diurnal loop of layer-dependent, coupled physics biases, whereby daytime errors precondition nighttime residual heating and in turn influences MSE and convection the following day. These biases stem primarily from convective parameterization, which converts cloud condensates especially ice too efficiently, producing excessive precipitation, biased clouds, and radiative errors. Limited mid-level convection and a missing shallow-to-deep transition generate a top-heavy heating structure that persists overnight, suppressing vertical energy transport, MSE buildup, and the inhibit development of deep convection the next day. This hierarchical, vertically resolved analysis provides process-based pathways for improving tropical energetics and representation of the MJO initiation in UFS and other prediction systems.