Collective Role of Thermocline and Zonal Advective Feedbacks in the ENSO Mode

Soon Il An, Fei Fei Jin

Research output: Contribution to journalArticle

119 Citations (Scopus)

Abstract

The vertical advection of anomalous subsurface temperature by the mean upwelling and the zonal advection of mean sea surface temperature (SST) by anomalous current are known to be essential for the equatorial SST anomaly associated with the El Niño-Southern Oscillation (ENSO). In the coupled model, these two processes are referred to as the thermocline feedback and the zonal advective feedback, respectively. Using a version of a recharge oscillator model for ENSO obtained from the stripped-down approximation of the Cane-Zebiak-type model, it is demonstrated that these two feedbacks, which are linked dynamically through the geostrophic approximation, tend constructively to contribute to the growth and phase transition of ENSO. However, these two feedbacks control the leading coupled mode in different ways. The thermocline feedback leads to a coupled mode through the merging of the damped SST mode and ocean adjustment mode, whereas the zonal advective feedback tends to destabilize the gravest ocean basin mode. With both of these feedbacks, the leading modes of the coupled model still can be traced back to these different origins under moderate changes in the model setup. The main consequence of these sensitivities is that the growth rate and frequency of the ENSO mode may be sensitive to slight changes in basic-state parameters, which control the strength of these feedbacks.

Original languageEnglish
Pages (from-to)3421-3432
Number of pages12
JournalJournal of Climate
Volume14
Issue number16
DOIs
Publication statusPublished - 2001 Aug 15

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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