THE RELATION OF MULTIPLE FLOW REGIMES TO THE CLIMATIC ERROR IN GENERAL-CIRCULATION MODELS - SOUTHERN-HEMISPHERE WINTER

CCM1 exhibits a distinct deficit in grid point 500mb height variance and insufficient persistence at large planetary-scale wave amplitude compared to observations or to CCM0. This deficit appears to be connected with the failure of CCM1 to simulate the observed planetary-scale flow regimes in the SH, exemplified in observations as bimodality in the wavenumber three amplitude. In particular, CCM1 does not achieve the observed large-amplitude wavenumber three regime. On the other hand, CCM0 does capture the wave amplitude bimodality and coincidentally has larger grid point height variance and greater persistence at large amplitude than CCM1. The CCM1 perpetual July SH climate resembles observed SH summer more closely than observed winter in terms of the wavenumber three amplitude distribution and the kinetic energy spectrum.