Weather regimes in the Pacific from a GCM

Abstract

Weather regimes have been sought by examining the 500-mb streamfunction of the UGAMP GCM run for 10 yr at T42 resolution with perpetual January forcing. Within the phase space of three to five EOFs, two local minima of the area-averaged ψ tendency are found. It is suggested that these patterns may be acting as "fixed points' within the atmospheric attractor, encouraging persistent flows and the formation of weather regimes. These dynamical attracting points are compared with a more conventional means of identifying weather regimes using a statistical maximum likelihood analysis of all model states during the 10-yr GCM run. -from Authors