To determine If the atmosphere exists in two preferred states, 500-mb heights from 36 different sets of 1,200-day integrations from the NCAR Community Climate Model (CCM, version DB) were analyzed. The planetary-wave amplitude Index and the projection index of the fields onto the leading empirica... Show moreTo determine If the atmosphere exists in two preferred states, 500-mb heights from 36 different sets of 1,200-day integrations from the NCAR Community Climate Model (CCM, version DB) were analyzed. The planetary-wave amplitude Index and the projection index of the fields onto the leading empirical orthogonal functions (EOF) were calculated and analyzed. The probability density function (PDF) of these indices was graphed for each dataset using the maximum penalized likelihood method (MPL). The majority of the PDF graphs do not seem to show bimodality, Indicating that the second maximum found by Hanson and Sutera is probably not significant. This outcome casts doubt on those studies which, after having been conducted using small datasets, have concluded that two distinct regimes influence the atmospheric variability. Show less
