Choi J., An S. I., Dewitte Boris, Hsieh W. W. (2009). Interactive feedback between the tropical pacific decadal oscillation and ENSO in a coupled general circulation model. Journal of Climate, 22 (24), p. 6597-6611. ISSN 0894-8755.
Titre du document
Interactive feedback between the tropical pacific decadal oscillation and ENSO in a coupled general circulation model
Journal of Climate, 2009,
22 (24), p. 6597-6611 ISSN 0894-8755
The output from a coupled general circulation model (CGCM) is used to develop evidence showing that the tropical Pacific decadal oscillation can be driven by an interaction between the El Nino-Southern Oscillation (ENSO) and the slowly varying mean background climate state. The analysis verifies that the decadal changes in the mean states are attributed largely to decadal changes in ENSO statistics through nonlinear rectification. This is seen because the time evolutions of the first principal component analysis (PCA) mode of the decadal-varying tropical Pacific SST and the thermocline depth anomalies are significantly correlated to the decadal variations of the ENSO amplitude (also skewness). Its spatial pattern resembles the residuals of the SST and thermocline depth anomalies after there is uneven compensation from El Nino and La Nina events. In addition, the stability analysis of a linearized intermediate ocean-atmosphere coupled system, for which the background mean states are specified, provides qualitatively consistent results compared to the CGCM in terms of the relationship between changes in the background mean states and the characteristics of ENSO. It is also shown from the stability analysis as well as the time integration of a nonlinear version of the intermediate coupled model that the mean SST for the high-variability ENSO decades acts to intensify the ENSO variability, while the mean thermocline depth for the same decades acts to suppress the ENSO activity. Thus, there may be an interactive feedback consisting of a positive feedback between the ENSO activity and the mean state of the SST and a negative feedback between the ENSO activity and the mean state of the thermocline depth. This feedback may lead to the tropical decadal oscillation, without the need to invoke any external mechanisms.
Plan de classement
Sciences du milieu [021]
;
Limnologie physique / Océanographie physique [032]
