Nonlinear Influences–A Key to Short-Term Climatic Perturbations

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  • 1 CSIRO, Division of Atmospheric Research, Mordialloc, Victoria, Australia
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Abstract

The role of nonlinear interactions in the climatic system in contributing to variability at both spatial and temporal levels is poorly understood. To gain some insight into the possible role of nonlinearities an elementary model has been devised. The model is capable of simulating interannual fluctuations substantially in agreement with observation. Very long term integrations (100 000 years) indicate that nonlinearities alone can produce noticeable climatic extremes, which could account for much of the observed anomalous behavior of the atmosphere. The nonlinearities in this particular model, however, are incapable of maintaining an extended climatic change. Short-term external forces in the model, less than one year, were not able to produce climatic perturbations extending beyond about two years. Finally it is shown that even for quite strong solar modulation of the model climate, nonlinearities are capable of intermittently disrupting this modulation. This suggests that a reassessment is needed of the rejection of claims for solar-induced climatic fluctuations on the grounds that such fluctuations are observed to breakdown.

Abstract

The role of nonlinear interactions in the climatic system in contributing to variability at both spatial and temporal levels is poorly understood. To gain some insight into the possible role of nonlinearities an elementary model has been devised. The model is capable of simulating interannual fluctuations substantially in agreement with observation. Very long term integrations (100 000 years) indicate that nonlinearities alone can produce noticeable climatic extremes, which could account for much of the observed anomalous behavior of the atmosphere. The nonlinearities in this particular model, however, are incapable of maintaining an extended climatic change. Short-term external forces in the model, less than one year, were not able to produce climatic perturbations extending beyond about two years. Finally it is shown that even for quite strong solar modulation of the model climate, nonlinearities are capable of intermittently disrupting this modulation. This suggests that a reassessment is needed of the rejection of claims for solar-induced climatic fluctuations on the grounds that such fluctuations are observed to breakdown.

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