Abstract
Observations of the Hudson River plume were taken in the spring of 2006 in conjunction with the Lagrangian Transport and Transformation Experiment using mooring arrays, shipboard observations, and satellite data. During this time period, the plume was subjected to a variety of wind, buoyant, and shelf forcings, which yield vastly different responses in plume structure including a downstream recirculating eddy. During weak and downwelling winds, the plume formed a narrow buoyant coastal current that propagated downstream near the internal wave speed. Freshwater transport during periods when the downwelling wind was closely aligned with the coast was near the river discharge values. During periods with a cross-shore component to the wind, freshwater transport in the coastal current estimated by the mooring array is less than the river discharge due to a widening of the plume that leads to the internal Rossby radius scaling for the plume width to be invalid. The offshore detachment of plume and formation of a downstream eddy that is observed surprisingly persisted for 2 weeks under a variety of wind forcing conditions. Comparison between mooring, shipboard, and satellite data reveal the downstream eddy is steady in time. Shipboard transects yield a freshwater content equal to the previous 3 days of river discharge. The feature itself was formed due to a large discharge following a strong onshore wind. The plume was then further modified by a brief upwelling wind and currents influenced by the Hudson Shelf Valley. The duration of the detachment and downstream eddy can be explained using a Wedderburn number which is largely consistent with the wind strength index described by Whitney and Garvine (J Geophys Res 110:C03014 1997).
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Acknowledgements
We would like to acknowledge the helpful comments from an anonymous reviewer, Eli Hunter and Chip Haldeman for their mooring work, Brad Butman for the HSV moorings, and support from the Institute of Marine and Coastal Scinces at Rutgers University and NSF awards OCE-0238957, OCE-0825833, and OCE-0928567.
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Responsible Editor: Chari Pattiaratchi
This article is part of the Topical Collection on Physics of Estuaries and Coastal Seas 2010
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Jurisa, J.T., Chant, R. The coupled Hudson River estuarine-plume response to variable wind and river forcings. Ocean Dynamics 62, 771–784 (2012). https://doi.org/10.1007/s10236-012-0527-7
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DOI: https://doi.org/10.1007/s10236-012-0527-7