Effects of Localized Grid Refinement on the General Circulation and Climatology in the Community Atmosphere Model

TitleEffects of Localized Grid Refinement on the General Circulation and Climatology in the Community Atmosphere Model
Publication TypeJournal Article
Year of Publication2015
JournalJournal of Climate
Volume28
Pages2777-2803
Date Published04/2015
Abstract / Summary

Using the spectral element (SE) dynamical core within the National Center for Atmospheric Research–Department of Energy Community Atmosphere Model (CAM), a regionally refined nest at 0.25 degree (28 km) horizontal resolution located over the North Atlantic is embedded within a global 1 degree (111 km) grid. A 23-yr simulation using Atmospheric Model Intercomparison Project (AMIP) protocols and default CAM, version 5, physics is compared to an identically forced run using the global 1 degree (111 km) grid without refinement. The addition of a refined patch over the Atlantic basin does not noticeably affect the global circulation. In the area where the refinement is located, large-scale precipitation increases with the higher resolution. This increase is partly offset by a decrease in precipitation resulting from convective parameterizations, although total precipitation is also slightly higher at finer resolutions. Equatorial waves are not significantly impacted when traversing multiple grid spacings. Despite the grid transition region bisecting northern Africa, local zonal jets and African easterly wave activity are highly similar in both simulations. The frequency of extreme precipitation events increases with resolution, although this increase is restricted to the refined patch. Topography is better resolved in the nest as a result of finer grid spacing. The spatial patterns of variables with strong orographic forcing (such as precipitation, cloud, and precipitable water) are improved with local refinement. Additionally, dynamical features, such as wind patterns, associated with steep terrain are improved in the variable-resolution simulation when compared to the uniform coarser run.

URLhttp://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00599.1
DOI10.1175/JCLI-D-14-00599.1
Journal: Journal of Climate
Year of Publication: 2015
Volume: 28
Pages: 2777-2803
Date Published: 04/2015

Using the spectral element (SE) dynamical core within the National Center for Atmospheric Research–Department of Energy Community Atmosphere Model (CAM), a regionally refined nest at 0.25 degree (28 km) horizontal resolution located over the North Atlantic is embedded within a global 1 degree (111 km) grid. A 23-yr simulation using Atmospheric Model Intercomparison Project (AMIP) protocols and default CAM, version 5, physics is compared to an identically forced run using the global 1 degree (111 km) grid without refinement. The addition of a refined patch over the Atlantic basin does not noticeably affect the global circulation. In the area where the refinement is located, large-scale precipitation increases with the higher resolution. This increase is partly offset by a decrease in precipitation resulting from convective parameterizations, although total precipitation is also slightly higher at finer resolutions. Equatorial waves are not significantly impacted when traversing multiple grid spacings. Despite the grid transition region bisecting northern Africa, local zonal jets and African easterly wave activity are highly similar in both simulations. The frequency of extreme precipitation events increases with resolution, although this increase is restricted to the refined patch. Topography is better resolved in the nest as a result of finer grid spacing. The spatial patterns of variables with strong orographic forcing (such as precipitation, cloud, and precipitable water) are improved with local refinement. Additionally, dynamical features, such as wind patterns, associated with steep terrain are improved in the variable-resolution simulation when compared to the uniform coarser run.

DOI: 10.1175/JCLI-D-14-00599.1
Citation:
Zarzycki, CM, C Jablonowski, DR Thatcher, and MA Taylor.  2015.  "Effects of Localized Grid Refinement on the General Circulation and Climatology in the Community Atmosphere Model."  Journal of Climate 28: 2777-2803.  https://doi.org/10.1175/JCLI-D-14-00599.1.