Zhang, Jiawei, Liu, Jingui, Li, Shuo and Pan, Shunqi  ORCID: https://orcid.org/0000-0001-8252-5991
2026.
Spatiotemporal variability and front-locked circulation of salinity fronts in Hangzhou Bay.
Estuarine, Coastal and Shelf Science
342
, 110179.
10.1016/j.ecss.2026.110179
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Abstract
Estuarine salinity fronts significantly regulate circulation, sediment dynamics, and pollutant transport in coastal systems. In Hangzhou Bay, a persistent northeast-southwest salinity front has been observed; however, its three-dimensional structure and dynamical maintenance remain poorly constrained, particularly under climate change conditions and intensifying anthropogenic pressures. Here, a high-resolution three-dimensional hydrodynamic model based on the Finite-Volume Community Ocean Model is developed to investigate the formation, variability, and governing dynamics of salinity fronts in Hangzhou Bay. Results show pronounced spatiotemporal variability in frontal intensity across seasonal and tidal scales. Surface frontal intensity peaks during wet-season neap tides, driven by enhanced salinity stratification and reduced tidal mixing, whereas dry-season variability is primarily modulated by strong northerly winds and associated Ekman transport. A clear spatial asymmetry in frontal structure is identified across the bay: north of the bay mouth, the water column remains well mixed, producing a predominantly vertical frontal structure. In contrast, the southern bay displays partially mixed to stratified conditions, forming inclined fronts, with the strongest salinity stratification occurring during wet-season neap tide. Within the frontal zone, coherent front-locked circulation develops as single and double clockwise circulation, accompanied by vertical velocities on the order of 10−6-10−5 m/s. Surface residual currents are generally stronger than bottom currents, which are significantly attenuated near the front due to bottom friction and the Coriolis effects. Momentum diagnostics demonstrate that this frontal system is maintained by a frictionally modified baroclinic balance, with wind forcing as a secondary modulator. This study provides a process-based framework applicable to other macrotidal estuarine systems.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Engineering |
| Additional Information: | RRS policy applied |
| Publisher: | Elsevier |
| ISSN: | 0272-7714 |
| Date of First Compliant Deposit: | 1 September 2026 |
| Date of Acceptance: | 11 August 2026 |
| Last Modified: | 01 Sep 2026 09:15 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/189165 |
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