Prognostic Aerosols in a Convection-permitting Earth System Model

Aerosols and their interactions with clouds and the boundary layer play a key role in the atmosphere. The impact of aerosol on atmospheric processes and climate is a function of emissions associated with human activity and natural variability. However, considerable uncertainty exists in predictions of aerosol number, size, composition, transport pathways of aerosol populations, and the direct and indirect effects of aerosols on the radiation budget. These phenomena need to be studied across multiple scales, which is the focus of the current study utilizing high-resolution global simulations. These simulations should capture the behavior of different aerosol species, including their optical properties and the processes they undergo, such as dry deposition, wet scavenging, and aerosol-cloud-radiation interactions.

We utilize the Simple Cloud Resolving E3SM Atmosphere Model (SCREAM), slated to be the atmosphere model of the Energy Exascale Earth System Model (E3SM) version 4. SCREAM is configured with a 4-mode C++/Kokkos Modal Aerosol Model (MAM4xx) for the prognostic treatment of aerosols—such as black carbon, dust, sea salt, sulfate, particulate organic matter, and secondary organic aerosol. Multiple simulations are conducted at varying grid resolutions using SCREAM to assess the impact of grid spacing on aerosol and aerosol-cloud-radiation interactions. For example, optical properties such as the aerosol optical depth and the single scattering albedo as well as dry and wet deposition of aerosol species are analyzed, alongside aerosol-cloud interaction statistics.

The study provides an initial comparative analysis of these optical and physical properties of aerosols across different spacial resolutions, examining their interaction with cloud macro-physical and micro-physical properties.