Ocean Dynamics

, Volume 64, Issue 3, pp 385–412 | Cite as

Study on subtidal circulation and variability in the Gulf of St. Lawrence, Scotian Shelf, and Gulf of Maine using a nested-grid shelf circulation model

Article
Part of the following topical collections:
  1. Topical Collection on the 16th biennial workshop of the Joint Numerical Sea Modelling Group (JONSMOD) in Brest, France 21-23 May 2012

Abstract

This paper examines the subtidal circulation and associated variability in the Gulf of St. Lawrence, the Scotian Shelf, and the Gulf of Maine (GSL-SS-GOM) in 1988–2004 based on results produced by a nested-grid shelf circulation model. The model has a fine-resolution child model (∼ (1/12)°) embedded inside a coarse-resolution parent model (∼ (1/4)°) of the northwest Atlantic. The combination of the semi-prognostic method and the spectral nudging method is used to reduce the model seasonal bias and drift. The child model reproduces the general features of the observed circulation and hydrography over the study region during the study period. The child model results demonstrate that the time-mean circulation in the GSL is affected by the time-mean atmospheric forcing and inflow through the Strait of Belle Isle. The temporal variability in atmospheric forcing affects the outflow through western Cabot Strait, which in turn affects the transport of the Nova Scotian Current and the gulf-wide cyclonic circulation in the GOM. The simulated seasonal variability of salinity in the top 30 m of the GSL-SS-GOM is mainly affected by the equatorward advection of low-salinity waters from the lower St. Lawrence Estuary to the GOM through the Scotian Shelf. The simulated intraseasonal variability of circulation in the GSL is affected by the variability in the estuarine circulation in response to the temporal variability in atmospheric forcing. On the Scotian Shelf, the intraseasonal variability is mainly driven by the variability of wind forcing and mesoscale and nonlinear dynamics over the shelf break and slope region. The interannual variability in the simulated temperature and salinity are spatially coherent in the intermediate waters in the GSL, which is caused partially by the local response to atmospheric variability and partially by variabilities over the southern Newfoundland Shelf that enter the GSL through the eastern Cabot Strait. By comparison, on the Scotian Shelf, the interannual variability of simulated circulation is affected by anomalies produced by the nonlinear dynamics which are advected equatorwards by the shelf break jet.

Keywords

Gulf of St. Lawrence Scotian Shelf Gulf of Maine Seasonal variability Interannual variability Intraseasonal variability Ocean circulation Estuarine circulation Fresh water plume 

Notes

Acknowledgments

This study was funded by the Ocean Tracking Network Canada, Lloyd’s Register Foundation (LRF), and the Natural Sciences and Engineering Research Council of Canada. LRF is a UK registered charity and sole shareholder of Lloyd’s Register Group Ltd, which invests in science, engineering and technology for public benefit, worldwide. The authors wish to thank Fred Dupont, Youyu Lu, Keith Thompson, Shiliang Shan, and Kyoko Ohashi for their comments. This study utilized ACEnet computational resources.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Department of OceanographyDalhousie UniversityHalifaxCanada

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