Singular Value Decomposition of Interannual Anomalies of Wind Stress and Sea Surface Temperature in the Equatorial Pacific Area

The relationship between interannual anomalies of wind stress and sea surface temperature (SST) in the equatorial Pacific area is analyzed using a singular value decomposition (SVD) scheme. The results show that the major pair of singular vectors is closely related with ENSO cycles and its main feature is the quasi-synchronous variations of the anomalous convergence (divergence) towards the equator of wind stress with the anomalous increase (decrease) of SST over the equatorial eastern and middle Pacific. The analyses of anomaly fields of the normalized wind stress during four E1 Nino events in the seventies and eighties show that there was the convergence of wind stresses over the equatorial eastern and middle Pacific in all four events. The results show that the singular value decomposition scheme of vector may be more reasonable and representative than trade relaxation in describing the circulation anomaly in ENSO cycles