CoAuthors

John Wilkin (IMCS, Rutgers, USA)

The Luzon Strait is the strait separating Luzon island of the Philippines and Taiwan. The most prominent dynamical feature of the area is the Kuroshio, the most important current in the North Pacific. This western boundary current flows northward along the northern tip of Luzon Island, where it veers westward and meanders while crossing the Luzon Strait to continue its path along the east coast of Taiwan. It therefore serves as a "semi-permeable barrier" mediating the interchange of surface waters between the western Pacific and the regional South China Sea. The combination of the Kuroshio Current, westward propagating eddies from the Pacific ocean, the monsoon, strong tides, and the dramatic topography of the Luzon Straits lead to a rich physical forcing environment that is not fully understood, specially at the meso- and submeso-scales. We present a data-assimilative two-way nested model application based on the Regional Ocean Modeling System (ROMS), designed to study mesoscale and submesoscale variability. The parent model of the nested application is constrained by satellite (SSH and SST) and in-situ hydrographic observations using variational data assimilation, effectively propagating the remotely-sensed surface information to the subsurface. The information content of the assimilated observations is then propagated to the scales not resolved by the parent model using a two-way nested approach, where the child grid benefits from the improved analysis in the parent model via the boundary interface between both grids. A preliminary evaluation of the performance of the system is presented, with special emphasis to the value added by the altimeter data.