A new simplified parameterization of secondary organic aerosol in the Community Earth System Model Version 2 (CESM2; CAM6.3) Journal Article uri icon

Overview

abstract

  • Abstract. The Community Earth System Model (CESM) community has been; providing versatile modeling options, with simple to complex chemistry and; aerosol schemes in a single model, in order to support the broad scientific; community with various research interests. While different model; configurations are available in CESM and these can be used for different; fields of Earth system science, simulation results that are consistent; across configurations are still desirable. Here we develop a new simple; secondary organic aerosol (SOA) scheme in the Community Atmosphere Model; (CAM) version 6.3, the atmospheric component of the CESM. The main purpose; of this simplified SOA scheme is to reduce the differences in aerosol; concentrations and radiative fluxes between CAM and CAM with detailed; chemistry (CAM-chem) while maintaining the computational efficiency of CAM.; CAM simulation results using the default CAM6 and the new SOA schemes are; compared to CAM-chem results as a reference. More consistent SOA; concentrations are obtained globally when using the new SOA scheme for both; temporal and spatial variabilities. The new SOA scheme shows that 62 % of grid; cells globally are within a factor of 2 compared to the CAM-chem SOA; concentrations, which is improved from 24 % when using the default CAM6; SOA scheme. Furthermore, other carbonaceous aerosols (black carbon and; primary organic aerosol) in CAM6 become closer to CAM-chem results due to; more similar microphysical aging timescales influenced by SOA coating,; which in turn leads to comparable wet deposition fluxes. This results in an; improved global atmospheric burden and concentrations at the high latitudes; of the Northern Hemisphere compared to the full chemistry version; (CAM-chem). As a consequence, the radiative flux differences between; CAM-chem and CAM in the Arctic region (up to 6 W m−2) are significantly; reduced for both nudged and free-running simulations. We find that the CAM6; SOA scheme can still be used for radiative forcing calculation as the high; biases exist both in pre-industrial and present conditions, but studies; focusing on the instantaneous radiative effects would benefit from using the; SOA scheme developed in this study. The new SOA scheme also has technical; advantages including the use of identical SOA precursor emissions as; CAM-chem from the online biogenic emissions instead of pre-calculated; emissions that may introduce differences. Future parameter updates to the; CAM-chem SOA scheme can be easily translated to the new CAM SOA scheme as it; is derived from the CAM-chem SOA scheme.;

publication date

  • July 12, 2023

has restriction

  • gold

Date in CU Experts

  • June 20, 2024 2:50 AM

Full Author List

  • Jo DS; Tilmes S; Emmons LK; Wang S; Vitt F

author count

  • 5

Other Profiles

Electronic International Standard Serial Number (EISSN)

  • 1991-9603

Additional Document Info

start page

  • 3893

end page

  • 3906

volume

  • 16

issue

  • 13