Long-range correlations and trends in global climate models: Comparison with real data

We study trends and temporal correlations in the monthly mean temperature data of Prague and Melbourne derived from four state-of-the-art general circulation models that are currently used in studies of anthropogenic effects on the atmosphere: GFDL-R15-a, CSIRO-Mk2, ECHAM4/OPYC3 and HADCM3. In all models, the atmosphere is coupled to the ocean dynamics. We apply fluctuation analysis, and detrended fluctuation analysis which can systematically overcome nonstationarities in the data, to evaluate the models according to their ability to reproduce the proper fluctuations and trends in the past and compare the results with the future prediction.