This project will exploit and further develop the GEOS-Chem atmospheric chemistry capability within the NCAR Community Earth System Model (CESM). It will contribute individual GEOS-Chem
components to the Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA), which is designed to provide a versatile multiscale atmospheric chemistry capability for the next generation of CESM. It will apply the unique resource of GEOS-Chem within CESM and through MUSICA to target pressing scientific questions related to our understanding of tropospheric ozone. The work will be driven by three objectives:

1.Implement modular GEOS-Chem components into MUSICA for photolysis, chemical mechanism including adaptive mechanism autoreduction, and wet deposition;
2.Apply the GEOS-Chem capability within CESM to better understand ozone air quality over East Asia and its connection to background tropospheric ozone;
3.Apply the GEOS-Chem capability within CESM to better understand aviation’s effects on tropospheric ozone.

In addition to the above objectives, this project will also provide support and documentation for CESM users to exploit the GEOS-Chem and Harmonized Emissions Component (HEMCO) capabilities within CESM, and it will contribute to software standards for MUSICA through early adoption of the infrastructure.