A Multidecadal Simulation of Atlantic Tropical Cyclones using a Variable-Resolution Global Atmospheric General Circulation Model

TitleA Multidecadal Simulation of Atlantic Tropical Cyclones using a Variable-Resolution Global Atmospheric General Circulation Model
Publication TypeJournal Article
Year of Publication2014
JournalJournal of Advances in Modeling Earth Systems
Volume6
Pages805–828
Date Published10/2014
Abstract / Summary

Using a variable-resolution option within the National Center for Atmospheric Research/Department of Energy Community Atmosphere Model (CAM) Spectral Element (SE) global model, a 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. The grid is designed such that fine grid cells are located where tropical cyclones (TCs) are observed to occur during the Atlantic TC season (June–November). Two simulations are compared, one with refinement and one control case with no refinement (globally uniform 1 degree grid). Both simulations are integrated for 23 years using Atmospheric Model Intercomparison Protocols. TCs are tracked using an objective detection algorithm.The variable-resolution simulation produces significantly more TCs than the unrefined simulation. Storms that do form in the refined nest are much more intense, with multiple storms strengthening to Saffir-Simpson category 3 intensity or higher. Both count and spatial distribution of TC genesis and tracks in the variable-resolution simulation are well matched to observations and represent significant improvements over the unrefined simulation. Some degree of interannual skill is noted, with the variable-resolution grid able to reproduce the observed connection between Atlantic TCs and the El Nino Southern Oscillation (ENSO). It is shown that Genesis Potential Index (GPI) is well matched between the refined and unrefined simulations, implying that the introduction of variable-resolution does not affect the synoptic environment. Potential ‘‘upscale’’ effects are noted in the variable-resolution simulation, suggesting stronger TCs in refined nests may play a role in meridional transport of momentum, heat, and moisture.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/2014MS000352/full
DOI10.1002/2014MS000352
Journal: Journal of Advances in Modeling Earth Systems
Year of Publication: 2014
Volume: 6
Pages: 805–828
Date Published: 10/2014

Using a variable-resolution option within the National Center for Atmospheric Research/Department of Energy Community Atmosphere Model (CAM) Spectral Element (SE) global model, a 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. The grid is designed such that fine grid cells are located where tropical cyclones (TCs) are observed to occur during the Atlantic TC season (June–November). Two simulations are compared, one with refinement and one control case with no refinement (globally uniform 1 degree grid). Both simulations are integrated for 23 years using Atmospheric Model Intercomparison Protocols. TCs are tracked using an objective detection algorithm.The variable-resolution simulation produces significantly more TCs than the unrefined simulation. Storms that do form in the refined nest are much more intense, with multiple storms strengthening to Saffir-Simpson category 3 intensity or higher. Both count and spatial distribution of TC genesis and tracks in the variable-resolution simulation are well matched to observations and represent significant improvements over the unrefined simulation. Some degree of interannual skill is noted, with the variable-resolution grid able to reproduce the observed connection between Atlantic TCs and the El Nino Southern Oscillation (ENSO). It is shown that Genesis Potential Index (GPI) is well matched between the refined and unrefined simulations, implying that the introduction of variable-resolution does not affect the synoptic environment. Potential ‘‘upscale’’ effects are noted in the variable-resolution simulation, suggesting stronger TCs in refined nests may play a role in meridional transport of momentum, heat, and moisture.

DOI: 10.1002/2014MS000352
Citation:
Zarzycki, CM, and C Jablonowski.  2014.  "A Multidecadal Simulation of Atlantic Tropical Cyclones using a Variable-Resolution Global Atmospheric General Circulation Model."  Journal of Advances in Modeling Earth Systems 6: 805–828.  https://doi.org/10.1002/2014MS000352.