Modeling Seasonal Variability in the Wind-driven Upper-Layer Circulation in the Indo–Pacific Region

Abstract

Abstract A basin-scale fine-resolution primitive equation reduced-gravity model forced by the climatological monthly wind of Hellerman and Rosenstein is used to study seasonal variability of the wind-driven upper-layer circulation in the Indo–Pacific region. The model domain is limited to the tropical Pacific Ocean and the eastern Indian Ocean. The use of the open boundary conditions allows the model to account for a net transport of mass from the Pacific to the Indian Ocean. An active eddy field is modeled east of Mindanao in the strong shear zone formed between the North Equatorial Current and the North Equatorial Countercurrent. This eddy field gives rise to the energetic shorter time scale variations in the western Pacific and appears to be responsible for considerable variability in surface currents noted previously. A distinct current bifurcation at the southern coast of New Britain in the Solomon Sea is modeled. The western branch of the resulting flow exits through Vitiaz Strait, while the eastern...