CORRELATION DIMENSIONS OF LOCAL, SHORT-TERM CLIMATIC ATTRACTORS FROM OBSERVATIONS AND A GLOBAL CLIMATE MODEL

Correlation dimensions nu were estimated for 500-mb geopotential heigh ts over eastern North America as predicted by the Atmospheric Environm ent Service-Canadian Climate Centre general circulation climate model (GCM). A value of 6.0 to 7.0 was obtained, which agrees to within expe rimental error with a previously estimated value determined from measu red data. This agreement is encouraging for it may suggest that on sho rt time scales, the GCM is capable of producing fluctuations on a regi onal scale that resemble those of the real atmosphere. For western Eur ope, however, observed and GCM time series of 500-mb geopotential heig hts yielded values for nu of about 8.0 and 6.0, respectively, but disp lay similar power spectra. In contrast, over the tropical Pacific, nu from GCM data either does not exist or exceeds 11. These results show that topologies of local climate attractors vary over the globe, thus making it difficult to speak of a global attractor.