The importance of high horizontal resolution and accurate coastline geometry in modeling South China Sea inflow

Abstract

As resolution is increased from 1/2/° to 1/32° in Pacific Ocean simulations using the NRL Layered Ocean Model, marked changes are found in the Kuroshio's mean pathway as it intrudes into the South China Sea (SCS) via the Luzon Strait. With increased horizontal resolution comes a more accurate representation of the coastline geometry associated with the Batan/Babuyan Islands within the strait, and a reduction in the modeled westward intrusion of the Kuroshio into the SCS. The 1/16° model is extremely sensitive to two very small scale shoals (Calayan Bank and a shoal north of Calayan Island) that are resolvable at this grid spacing. The exclusion of these three model gridpoints significantly alters the mean Kuroshio pathway to resemble the pathway from the 1/8° model. In addition excluding all islands within the Luzon Strait in the 1/16° model gives a deep intrusion mean pathway as found in the 1/2° model.