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Unusual Cross‐Shelf Transport Driven by the Changes of Wind Pattern in a Marginal Sea
Author(s) -
Yao Zhigang,
Chen Ke,
Ding Yang,
Lin Xiaopei,
Bao Xianwen,
Qiao Lulu
Publication year - 2021
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2021jc017526
Subject(s) - hydrography , wind stress , submarine pipeline , current (fluid) , climatology , geology , anomaly (physics) , oceanography , hydrographic survey , vorticity , boundary current , ocean current , sea surface temperature , circulation (fluid dynamics) , global wind patterns , potential vorticity , trade wind , meteorology , vortex , geography , physics , thermodynamics , condensed matter physics
The traditional understanding of the regional circulation in the Northwest Pacific marginal seas is that the Korean Coastal Current flows southward, following the isobaths of 20–50 m. However, an unusual tongue‐shaped structure of cold water is observed in satellite SST data in January 2017, indicating a possible offshore spread of cold coastal water into the middle Southern Yellow Sea (SYS). Additional observations, including in situ hydrographic data as well as direct current measurement, also suggest this cross‐shelf transport of the Korean Coastal Water in January 2017. Our analysis shows that this flow breaks through the isobaths at ∼37°N, moves southward between 50–75 m, and eventually veers anti‐cyclonically at ∼35°N to join the western slope of the SYS. This circulation pattern is further supported by heat budget analysis. Diagnosis of potential vorticity (PV) reveals that the elevated negative PV anomaly imposed by surface wind stress favors this unusual cross‐shelf transport. The change of wind pattern, although under a deceasing wind speed condition, plays an important role. This work provides an alternative view of the wintertime circulation pattern and motivates future studies of the variability of the coastal currents over interannual and longer time scales in the SYS.