Articles | Volume 13, issue 5
Nonlin. Processes Geophys., 13, 531–540, 2006
https://doi.org/10.5194/npg-13-531-2006
Nonlin. Processes Geophys., 13, 531–540, 2006
https://doi.org/10.5194/npg-13-531-2006

  10 Oct 2006

10 Oct 2006

Multi-parameter uncertainty analysis of a bifurcation point

B. Knopf1, M. Flechsig1, and K. Zickfeld2 B. Knopf et al.
  • 1Potsdam Institute for Climate Impact Research, P.O. Box 60 12 03, 14412 Potsdam, Germany
  • 2School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada

Abstract. Parameter uncertainty analysis of climate models has become a standard approach for model validation and testing their sensitivity. Here we present a novel approach that allows one to estimate the robustness of a bifurcation point in a multi-parameter space. In this study we investigate a box model of the Indian summer monsoon that exhibits a saddle-node bifurcation against those parameters that govern the heat balance of the system. The bifurcation brings about a change from a wet summer monsoon regime to a regime that is characterised by low precipitation. To analyse the robustness of the bifurcation point itself and its location in parameter space, we perform a multi-parameter uncertainty analysis by applying qualitative, Monte Carlo and deterministic methods that are provided by a multi-run simulation environment.

Our results show that the occurrence of the bifurcation point is robust over a wide range of parameter values. The position of the bifurcation, however, is found to be sensitive on these specific parameter choices.