The impact of Eastern‐Pacific versus Central‐Pacific El Niños on the North Equatorial Countercurrent in the Pacific Ocean

Using a three‐dimensional ocean reanalysis data product, the influence of two types of the El Niños on the North Equatorial Countercurrent (NECC) across the Pacific basin is examined in this study. Eastern‐Pacific El Niños (EP‐El Niños) exert a significant impact on the interannual changes of the NECC, whereas Central‐Pacific El Niños (CP‐El Niños) have little influence. From the developing to mature phase of the EP‐El Niños that occur s frequently in the latter half of a calendar year, the NECC tends to intensify and shift southward. While the EP‐El Niño‐related position changes of the NECC is out of phase with its seasonal position changes, the EP‐El Niño‐related intensity variability of the NECC is in phase with its seasonal modulation. During both types of El Niños, the El Niño‐modulated wind stress curl forcing changes the upper ocean thickness, modifying the NECC intensity and central position. The weaker and shorter fluctuations of wind stress curl forcing during the CP‐El Niño events induce irregular and insignificant changes of the NECC.