Submitted as: development and technical paper 16 Dec 2020

Submitted as: development and technical paper | 16 Dec 2020

Review status: a revised version of this preprint is currently under review for the journal GMD.

Grid-Stretching Capability for the GEOS-Chem 13.0.0 Atmospheric Chemistry Model

Liam Bindle1,2, Randall V. Martin1,2,3, Matthew J. Cooper2,1, Elizabeth W. Lundgren4, Sebastian D. Eastham5, Benjamin M. Auer6, Thomas L. Clune6, Hongjian Weng7, Jintai Lin7, Lee T. Murray8, Jun Meng2,1,9, Christoph A. Keller6,10, Steven Pawson6, and Daniel J. Jacob4 Liam Bindle et al.
  • 1Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, Missouri, USA
  • 2Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
  • 3Harvard-Smithsonian Centre for Astrophysics, Cambridge, MA, USA
  • 4John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
  • 5Laboratory for Aviation and the Environment, Massachusetts Institute of Technology, Cambridge, MA, USA
  • 6Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 7Laboratory for Climate and Ocean–Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
  • 8Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, USA
  • 9Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California, USA
  • 10Universities Space Research Association, Columbia, MD, USA

Abstract. Modeling atmospheric chemistry at fine resolution globally is computationally expensive; the capability to focus on specific geographic regions using a multiscale grid is desirable. Here, we develop, validate, and demonstrate stretched-grids in the GEOS-Chem atmospheric chemistry model in its high performance implementation (GCHP). These multiscale grids are specified at runtime by four parameters that offer users nimble control of the region that is refined and the resolution of the refinement. We validate the stretched-grid simulation versus global cubed-sphere simulations. We demonstrate the operation and flexibility of stretched-grid simulations with two case studies that compare simulated tropospheric NO2 column densities from stretched-grid and cubed-sphere simulations to retrieved column densities from the TROPOspheric Monitoring Instrument (TROPOMI). The first case study uses a stretched-grid with a broad refinement covering the contiguous US to produce simulated columns that perform similarly to a C180 (~50 km) cubed-sphere simulation at less than one-ninth the computational expense. The second case study experiments with a large stretch-factor for a global stretched-grid simulation with a highly localized refinement with ~10 km resolution for California. We find that the refinement improves spatial agreement with TROPOMI columns compared to a C90 cubed-sphere simulation of comparable computational demands, despite conducting the simulation at a finer resolution than parent meteorological fields. Overall we find that stretched-grids in GEOS-Chem are a practical tool for fine resolution regional- or continental-scale simulations of atmospheric chemistry. Stretched-grids are available in GEOS-Chem version 13.0.0.

Liam Bindle et al.

Status: final response (author comments only)
Status: final response (author comments only)
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Liam Bindle et al.

Liam Bindle et al.


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Short summary
Atmospheric chemistry models like GEOS-Chem are versatile tools widely used in air pollution and climate studies. The simulations used in such studies can be very computationally demanding, so it is useful if the model can simulate a specific geographic region at a higher resolution than the rest of the globe. Here, we implement, test, and demonstrate a new variable-resolution capability in GEOS-Chem that is suitable for simulations conducted on supercomputers.