Journal cover Journal topic
Nonlinear Processes in Geophysics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.558 IF 1.558
  • IF 5-year value: 1.475 IF 5-year
    1.475
  • CiteScore value: 2.8 CiteScore
    2.8
  • SNIP value: 0.921 SNIP 0.921
  • IPP value: 1.56 IPP 1.56
  • SJR value: 0.571 SJR 0.571
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 55 Scimago H
    index 55
  • h5-index value: 22 h5-index 22
Volume 5, issue 1
Nonlin. Processes Geophys., 5, 39–52, 1998
https://doi.org/10.5194/npg-5-39-1998
© Author(s) 1998. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
Nonlin. Processes Geophys., 5, 39–52, 1998
https://doi.org/10.5194/npg-5-39-1998
© Author(s) 1998. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.

  31 Mar 1998

31 Mar 1998

The nonlinear evolution of unstable coupled equatorial ocean-atmosphere modes

P. C. F. van der Vaart and H. A. Dijkstra P. C. F. van der Vaart and H. A. Dijkstra
  • Institute for Marine and Atmospheric Research Utrecht, Utrecht University, The Netherlands

Abstract. In this paper we investigate whether observed intraseasonal variability in the equatorial Pacific can be attributed to finite amplitude waves resulting from unstable air-sea interactions. Within a Zebiak - Cane type model of the coupled equatorial ocean - atmosphere, the nonlinear equilibration of instabilities of a simple basic state is considered with periodic conditions on the ocean boundaries. Three mechanisms exist which can induce a finite amplitude equilibration on a time scale ε2t. Here t is the characteristic time scale of growth of the disturbance and ε the relative distance from the instability threshold. For each equilibration mechanism, the finite amplitude and period of the equilibrium state are computed as a function of ε and substantial amplitude can be reached for a reasonable degree of supercriticality. Thereafter the analysis is extended to include time-dependent external forcing. It is shown that interannual variability may result through the interaction of the response of a weak annual external forcing and the finite amplitude development of the intraseasonal instabilities.

Publications Copernicus
Download
Citation