Effective resolution in high resolution global atmospheric models for climate studies

Abstract

We estimate the extent of spatial scales that atmospheric models in a new generation of global climate models, used in the Coupled Model Intercomparison Project 6, are able to resolve on the basis of kinetic energy spectra, commonly referred to as the effective resolution. We examine the spectra derived from the rotational and divergent parts of the wind for six state-of-the-art global climate models that have been run with at least two horizontal resolutions. For each of the high resolution configurations, the effective resolution enhancement is less than proportional to the increase of the nominal resolution. The highest effective resolution obtained by the models in this study is roughly 200 km. This shows that the newest generation of high resolution climate models starts to resolve synoptic scales relevant for the dynamics of weather events.