Mesoscale Convective Systems in DYAMOND Global Convection‐Permitting Simulations. Issue 4 (18th February 2023) - Feng, Zhe
Abstract: This study examines the deep convection populations and mesoscale convective systems (MCSs) simulated in the DYAMOND (DYnamics of the atmospheric general circulation modeled on non‐hydrostatic domains) winter project. A storm tracking algorithm is applied to six DYAMOND simulations and a global high‐resolution satellite cloud and precipitation data set for comparison. The simulated frequencies of tropical deep convection and organized convective systems vary widely among models and regions, although robust MCSs are generally underestimated. The diurnal cycles of MCS initiation and mature stages are well simulated, but the amplitudes are exaggerated over land. Most models capture the observed MCS lifetime, cloud shield area, rainfall volume and movement speed. However, cloud‐top height and convective rainfall intensity are consistently overestimated, and stratiform rainfall area and amount are consistently underestimated. Possible causes for the model differences compared to observations and implications for future model developments are discussed. Plain Language Summary: A new class of high‐resolution global atmosphere models is emerging for Earth system modeling. These new models can directly simulate convective storm systems and hold promises to improve the simulation of hydrological extremes such as flood‐producing rainfall and how they may change in future climate. This study assesses the fidelity of simulated convective storms from six global models against high‐resolution satellite observations. We find that the models simulate widely different frequency of convective storms in the tropics, but many do not produce storms that grow as large as observed. Several important aspects of observed storms such as the diurnal cycle, land‐ocean contrast, and storm rainfall amount are reasonably captured by the models; however, precipitation intensity is consistently overestimated and the storm rainfall area is too small. We further discussed potential causes for the model differences with observations and future model development needs. Key Points: Deep convective clouds and mesoscale convective systems are tracked in global convection‐permitting simulations and satellite observations Models produce a diverse range of tropical deep convective systems and MCS frequencies and their proportions in key climate regions Models reasonably simulate tropical MCS diurnal cycle and some MCS characteristics, but overestimate MCS precipitation intensity