Extratropical dynamics in the ACME atmosphere model

Abstract

Two AMIP-type simulations from an early Accelerated Climate Model for Energy (ACME) model V0.3 with 1 and 1/4 degree resolutions are evaluated to determine how well they characterize the midlatitude dynamics and atmospheric variability.  We present the model’s ability to capture  the variability of the jet stream, the key features of midlatitude phenomena, spanning the synoptic-scale to low-frequencies.

To examine the mutual influence between transient and stationary eddies, the characteristics of Northern Hemisphere atmospheric blocking events are evaluated. The spatial and temporal characteristics of atmospheric blocking are compared between NCEP/NCAR reanalysis and the two simulations. The blocking spatial distribution indicates a more accurate blocking representation in 1/4 degree resolution simulation over western North America, and a more realistic characteristic timescale of the phenomenon. The case composite and the wave activity analysis suggest a distinct eddy-mean flow interaction characteristic over North Pacific and North Atlantic.