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

We study trends and temporal correlations in the monthly mean temperature d ata of Prague and Melbourne derived from four state-of-the-art general circ ulation 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 fluctuati on analysis, and detrended fluctuation analysis which can systematically ov ercome nonstationarities in the data, to evaluate the models according to t heir ability to reproduce the proper fluctuations and trends in the past an d compare the results with the future prediction. (C) 2001 Elsevier Science B.V. All rights reserved.