Scaling of atmosphere and ocean temperature correlations in observations and climate models

Power-law scaling of near surface air temperature fluctuations and its geographical distribution is analyzed in 100-yr observations and in a 1000-yr simulation of the present-day climate with a complex atmosphere-ocean model. In observations and simulation detrended fluctuation analysis leads to the scaling exponent alpha approximate to 1 over the oceans, alpha approximate to 0.5 over the inner continents, and alpha approximate to 0.65 in transition regions [spectrum S(f) similar to f(-beta), beta = 2alpha - 1]. Scaling up to decades is demonstrated in observations and coupled atmosphere-ocean models with complex and mixed-layer oceans. Only with the complex ocean model the simulated power laws extend up to centuries.