Chemistry Climate Working Group (CCWG)

The goal of the Chemistry Climate Working Group (CCWG) is to continue to develop the representation of chemical gas and aerosol species in the CESM with the aim to improve our knowledge of the interactions between chemistry, aerosols and climate. CCWG science topics include past, present and future atmospheric composition in the troposphere and lower- to mid- stratosphere; interactions between atmospheric composition and other components of the Earth System (including land, ocean and ice); stratosphere-troposphere coupling; aerosol direct and indirect effects on the Earth's energy balance; aerosol effects on precipitation; and the impacts of chemistry and aerosol on both climate and air quality across multiple spatiotemporal scales.

CESM2 CAM-chem will serve as the new workhorse model to perform fully-coupled experiments for CMIP7, including comprehensive tropospheric and stratospheric chemistry (MOZART TS1). CAM-chem will provide the aerosol and chemistry fields to be prescribed in CAM7 with simple chemistry for longer climate-scale simulations. The new model lid is at 80 km, and comprises 93 vertical layers with a default horizontal resolution of about 1 degree on a cubed sphere, run on a spectral element dynamical core.  

CAM-chem can be run as a free-running climate model, coupled to the land model (CLM), and optionally to the ocean and ice models. It can also be nudged to winds and temperatures of meteorological reanalyses, with a default of using MERRA2 and GEOS5 fields, for detailed comparisons to field experiments and specific observations. 

Upcoming developments will prioritize evaluation and improvement of CAM7-chem. In addition, configurations of CAM-chem will be developed that support regionally refined model grids and data assimilation for regional impact studies (air quality and climate). Our long-term goal is to facilitate  greater flexibility for users to select different options of chemistry and aerosols schemes, in collaboration with the MUSICA and SIMA frameworks.

Atmopsheric chemistry modeling

The Chemistry Climate Working Group welcomes new users of CESM2 and CAM-chem (Low 40 km and Mid-Top 80 km) and WACCM (High-Top 140 km). You can find more information about WACCM from the Whole Atmosphere Working Group. To help new users get started, we have a wiki page along with helpful guides. For more information about CESM2 with chemistry see the links below:

• Wiki Page
• CAM Users Guide
• CAM Scientific Guide

Support Forum

Support for running CESM is available on the DiscussCESM bulletin board, where users can request assistance with science and runtime issues. The bulletin board includes a CAM-chem support forum section as well as a WACCM support forum section.

The announcements section of the forum contains guides of general use to CCWG users as well as announcements from CSEG.

Detailed instruction on how to run CESM with chemistry can be found in the Community & User Support