Fluctuation-dissipation theorem on attractors of atmospheric models

- This study deals with the numerical verification of the fluctuation-dissipation theorem (FDT) for atmospheric models. The theorem relates the impulse response operator of a system to its statistical characteristics (lag correlation coefficients). Consequently, the FDT can be used for the prediction of system sensitivity to small external perturbations. Though the FDT was obtained for equilibrium regular systems, it is clear from our calculations that the FDT is valid with sufficiently high accuracy for attractors of some atmospheric models (barotropic and two-level quasigeostrophic ones) as well. Numerical experiments with these two models show that the FDT can be successfully used for predicting model responses to small external perturbations of the external forcing.