Variability of the western Pacific warm pool structure associated with El Niño.
- Resource Type
- Article
- Authors
- Hu, Shijian; Hu, Dunxin; Guan, Cong; Xing, Nan; Li, Jianping; Feng, Junqiao
- Source
- Climate Dynamics. Oct2017, Vol. 49 Issue 7/8, p2431-2449. 19p.
- Subject
- *HEAT budget (Geophysics)
*OCEAN temperature
*UPWELLING (Oceanography)
*ROSSBY waves
EL Nino
- Language
- ISSN
- 0930-7575
Sea surface temperature (SST) structure inside the western Pacific warm pool (WPWP) is usually overlooked because of its distinct homogeneity, but in fact it possesses a clear meridional high-low-high pattern. Here we show that the SST low in the WPWP is significantly intensified in July-October of El Niño years (especially extreme El Niño years) and splits the 28.5 °C-isotherm-defined WPWP (WPWP split for simplification). Composite analysis and heat budget analysis indicate that the enhanced upwelling due to positive wind stress curl anomaly and western propagating upwelling Rossby waves account for the WPWP split. Zonal advection at the eastern edge of split region plays a secondary role in the formation of the WPWP split. Composite analysis and results from a Matsuno-Gill model with an asymmetric cooling forcing imply that the WPWP split seems to give rise to significant anomalous westerly winds and intensify the following El Niño event. Lead-lag correlation shows that the WPWP split slightly leads the Niño 3.4 index. [ABSTRACT FROM AUTHOR]