Oceanography | Vol. 38, No. 3
40
Oceanography | Vol. 38, No. 3
40
FEATURE ARTICLE
ABSTRACT. The dynamics governing nutrient concentrations in the ocean are primarily influenced by geophysical and biogeochem-
ical processes that regulate the introduction of these elements into seawater and their transport, dispersion, and removal. In one of the
world’s most productive marine regions, the East China Sea (ECS), numerous reports have documented the relationship between biolog-
ical productivity on the shelf and the nutrients primarily supplied from the subsurface waters of the Kuroshio, a powerful western bound-
ary current. However, the mechanism behind this nutricline variation is not well understood. In this study, we trace macronutrients from
the Kuroshio’s source to the ECS shelf. As the Kuroshio flows northward along the eastern coast of the Philippines to the southern Luzon
Strait (LS), part of it intrudes into the South China Sea (SCS) through the strait. Due to vigorous vertical mixing and upwelling, the ther-
mocline and nutricline are elevated in the SCS compared with those near the origin of the Kuroshio. Subsequently, at the northern LS,
the SCS outflow merges with the Kuroshio’s western side. This process preconditions the upwelling of nutrient-rich subsurface Kuroshio
waters onto the ECS shelf.
Estimated nitrate concentration contours along five sections from the north-
eastern coast of the Philippines (18°N) to northeastern Taiwan (25.2°N), based
on shipboard CTD temperature data collected in September 2000.
NUTRIENT FOOTPRINT
FROM THE ORIGIN OF THE KUROSHIO CURRENT
TO THE EAST CHINA SEA CONTINENTAL SHELF
By Ting-Hsuan Huang and Chen-Tung Arthur Chen