TITLE:
Boundary Phosphate Transport of the East China Sea and Its Influence on Biological Process
AUTHORS:
Zhijian Lin, Xiaochun Wang, Peng Xiu, Fei Chai, Qiong Wu
KEYWORDS:
Boundary Phosphate Transport, East China Sea, Biological Process
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.9,
September
24,
2019
ABSTRACT:
The East China Sea (ECS) is one of
the largest marginal seas in the Northwest Pacific, and also one of the most
productive regions of the global ocean. Using a three-dimensional Pacific
physical-biological model, we investigate the interannual variation of
phosphate transport via Kuroshio intrusion (KIPT) in the eastern boundary of
the East China Sea (ECS) and its influence on the ECS biological process during
1997 to 2016. The KIPT into the ECS mainly occurs in the northeast of Taiwan
and southwest of Kyushu, with stronger interannual variability in the northeast
of Taiwan. The variation of the KIPT is more significant in the near-bottom
water, and is dominated by volume transport. On the interannual timescale, the
KIPT changes in response to the shift of the Kuroshio axis and to the bottom
upwelling in the ECS eastern boundary. When the Kuroshio axis is closer to (farther
away from) the ECS shelf, the strength of the bottom upwelling increases (decreases).
This process induces more (less) significant topographic beta spiral, which
causes an anticyclonic (cyclonic) eddy-like bottom velocity feature in the
northeast of Taiwan. Eventually, more phosphate is transported to the ECS inner
shelf, which increases chlorophyll
concentration around the Zhoushan Islands and Yangtze Estuary but reduces
chlorophyll concentration in the ECS outer shelf. Conversely, the
chlorophyll increases in the ECS outer shelf but decreases around the Zhoushan Islands and Yangtze Estuary when
there is less phosphate transport. This study highlights the importance of Kuroshio
intrusion in connecting the inner and outer shelves of the ECS on the interannual
timescale. Phosphate transport into the East China Sea via Kuroshio intrusion shows
great interannual variability in the northeast of Taiwan. On the interannual
timescale, the variation of phosphate transport into the East China Sea via Kuroshio intrusion is dominated by volume
transport. When the Kuroshio axis is closer to the East China Sea shelf, there
is more phosphate transport into the East China Sea, and chlorophyll
increases around the Zhoushan Islands and Yangtze Estuary.