Tropical Cirrus Life Cycle and Top-of-Atmosphere Radiative Fluxes in Global Storm-Resolving Models

Cirrus clouds of various thicknesses and radiative characteristics extend over much of the tropics, especially around deep convection. They can be difficult to observe due to their high altitude and sometimes small optical depths. They are also difficult to simulate in conventional global climate models, which have coarse grid spacings and simplified parameterizations of deep convection and cirrus formation. We investigate the representation of tropical cirrus in global storm-resolving models (GSRMs), which have higher spatial resolution and explicit convection and could more accurately represent cirrus cloud processes. This study uses GSRMs from the DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains (DYAMOND) project. The aggregate life cycle of tropical cirrus is analyzed using joint albedo and outgoing longwave radiation (OLR) histograms to assess the fidelity of models in capturing the observed cirrus cloud populations over representative tropical ocean and land regions. The proportions of optically-thick deep convection, anvils and cirrus vary across models and are reflected in the vertical distribution of cloud cover and top-of-atmosphere radiative fluxes. Model differences in cirrus populations, likely driven by sub-grid processes such as ice microphysics, dominate over regional differences between convectively-active tropical land and ocean locations.