Indirect and direct aerosol feedback in the global and regional scale NOAA UFS Weather Model

Aerosols play a significant role in the radiation and atmospheric precipitation physics of microphysics and convection, and have a significant impact on air quality, visibility, public health, aviation, and climate. A physics suite, which includes the aerosol-aware double momentum Thompson-Eidhammer microphysics scheme (TH-E MP), the scale-aware and aerosol-aware Grell-Freitas (GF) convection scheme, and the MYNN-EDMF boundary layer and shallow cloud scheme, was developed at NOAA Global System Laboratory (GSL). The GSL physics suite is applied in the FV3GFS global model and the Rapid Refresh Forecast System (RRFS) regional model. We also developed the RRFS – Smoke and Dust model (RRFS-SD) at NOAA GSL with the Common Community Physics Package (CCPP), which is designed to facilitate a host-model agnostic implementation of physics parameterizations. Because of the interactive and strongly coupled nature of chemistry and physics, it is natural to allow for the smoke, dust and other chemical modules to be called directly from the physics suite. Here we embedded the plume rise modules for wildfire, sea-salt, dust, and anthropogenic emission modules into the regional model of RRFS and global UFS model using CCPP as subroutines of physics. The prognostic emissions of sea-salt, and organic carbon are combined to represent the “water friendly” aerosol emission, while the prognostic emission of dust is used to represent “ice friendly” aerosol emission for TH-E MP. With this implementation, we examined the aerosol indirect feedback when using the TH-E scheme in the global FV3GFS forecast with C768 (~13km) horizontal resolution and 127 vertical levels. There are significant cloud-radiation responses to the aerosol differences, and the severely positive precipitation bias over Europe and North America is significantly alleviated when applying this aerosol emission method for indirect feedback. We also examined the smoke direct feedback to the radiation in the RRFS-SD with 3km horizontal resolution and 64 vertical layers for September, 2020 during which the western US experienced extreme wildfires. The aerosol direct feedback run significantly improves the forecast of aerosol optical depth, surface 2m air temperature, 10m wind speed, and radiation fluxes.