The Dynamic of Convergence Zone Displacement in Western Pacific Ocean on 2015 Super El Niňo Event

Abstract

Warm pool and the existence of equatorial processes in the Pacific Ocean have an important role on El-Nino Southern Oscillation (ENSO). The eastward advection of warm and less saline water from the western Pacific together with the westward advection of cold and more saline water from the central-eastern Pacific induces a convergence of water masses at the eastern edge of the warm pool. The aim of this study is to determine convergence zone displacement in Western Pacific Ocean based on oceanography parameters such as temperature, salinity and surface current from insitu Argo Float, satellite and model data. The convergence zone displacement was characterized by proxies variable of isotherm 28,5 °C and isohaline 34,6 psu. The convergence zone is zonally displaced in association with EI Niño-La Niña and wind-driven surface current variations. The displacement of the convergence zone moved as far east as 136 °W in the eastern Pacific during the 2015 Super El Niňo. Otherwise, convergence zone moved westward near 154 °E in the western Pacific, during La Niňa periods. During Super El Niňo, the stronger-than-normal speed of the North Equatorial Counter Current (NECC) was increased by 0,8 m/s and appears to have been a major factor in convergence zone reaching the far eastern Pacific. A strong significant positive correlation (R= 0.88, 0.82 and 0.84) between SST and skipjack tuna catch on Super El Niňo, La Niňa and Normal respectively suggested that changes in skipjack CPUE occurred in phase with movement of convergence zone.