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Detachment of Low‐Salinity Water From the Yellow River Plume in Summer
Author(s) -
Yu Xiaojie,
Guo Xinyu,
Gao Huiwang
Publication year - 2020
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016344
Subject(s) - salinity , hydrography , plume , oceanography , spring (device) , geology , current (fluid) , water mass , hydrology (agriculture) , discharge , temperature salinity diagrams , estuary , environmental science , drainage basin , meteorology , geography , cartography , engineering , mechanical engineering , geotechnical engineering
Historical hydrographic data reveal that low‐salinity water can detach from the Yellow River plume in summer. In this study, the mechanism of this detachment is examined using a three‐dimensional numerical model that reproduced the observed detachment, including the position and size of the detached low‐salinity water patch. Sensitivity experiments showed that tide‐induced residual currents and tidal mixing around the Yellow River mouth played key roles in the detachment during spring tide. During the transition from neap tide to spring tide, the intensification of the northward tide‐induced residual current and the weakening of the southward density‐driven current lead to a net northward residual current (0.03 m/s), transporting high‐salinity water to the southern area of low‐salinity water. Meanwhile, the gradually strengthened tidal mixing also increased surface salinity, which was apparent in the central area of low‐salinity water. With the combination of these two effects, the low‐salinity water was separated into two parts during spring tide; that is, detachment of low‐salinity water occurred. The above scenario works with a condition of no wind. With the prevailing southeasterly winds during summer, the northeastward wind‐induced surface current promoted detachment by moving the detached low‐salinity water northeastward and enlarging its size. In contrast, the northerly wind that prevails in the other seasons drove low‐salinity water southward, which then flowed along the coast and hindered detachment. Consequently, the detachment of low‐salinity water from the Yellow River plume occurs only in summer.