Eddy-Resolving Simulations of the Asian Marginal Seas and Kuroshio Using ROMS


Y. Tony Song

JPL, California Institute of Technology, Pasadena, California


Tao Tang

Hong Kong Baptist University, Kowloon Tong, Hong Kong



The western North Pacific region is characterized by complex geometry and consists of many peninsulas, islands, straits, and passages dividing into several marginal seas and coastal oceans. The Asian marginal seas, including the South and East China seas, Sea of Japan, and Philippine Sea, interacting with Kuroshio circulations and the Indonesian throughflow, is one of the most challenging problems in ocean modeling. Surrounded by the coastal waters, East Asia is one of the highly populated and industrialized regions in the world. As a consequence, high rates of anthropogenic emissions and discharged materials into coastal waters, spreading globally after passing through the marginal seas, have been observed in the region. Their effects on the marine environment locally and globally are rather less known.

In his study, an eddy-resolving free-surface primitive-equations model is established for the Asian Marginal seas and their adjacent waters. The model uses a nonlinear terrain-following coordinate system for a better representation of bottom topography and narrow passages. The model domain has a horizontal resolution of one sixth degree (about 18.5 km) extending from 100E to 155E and from 5S to 45N with topography from shallow 20 m to deep 5000 m. The model is initialized with the Levitus annual climatology data and forced by the monthly mean air-sea fluxes of momentum, heat, and freshwater derived from COADS. Based on state-of-the-art modeling techniques and observational data, we investigate the exchanges of waters among the marginal seas and the effect of Kuroshio variations under monsoon wind forcing. High-resolution is identified as an important factor of representing the exchanges of waters through narrow straits and passages among the seas and their adjacent waters. Particular attention is given to determining open boundary conditions which are critical for the successful simulations.