Transport in the Hudson estuary: A modeling study of estuarine circulation and tidal trapping

LDEO Publication: 
Publication Type  Journal Article
Year of Publication  2004
Authors  Hellweger, F. L.; Blumberg, A. F.; Schlosser, P.; Ho, D. T.; Caplow, T.; Lall, U.; Li, H. H.
Journal Title  Estuaries
Volume  27
Issue  3
Pages  527-538
Journal Date  Jun
ISBN Number  0160-8347
Accession Number  ISI:000222292500015
LDEO Publication Number  6609
Key Words  new-york harbor; dispersion; ocean

The effects of estuarine circulation and tidal trapping on transport in the Hudson estuary were investigated by a large-scale, high-resolution numerical model simulation of a tracer release. The modeled and measured longitudinal profiles of surface tracer concentrations (plumes) differ from the ideal Gaussian shape in two ways: on a large scale the plume is asymmetric with the downstream end stretching out farther, and small-scale (1-2 km) peaks are present at the upstream and downstream ends of the plume. A number of diagnostic model simulations (e.g., remove freshwater flow) were performed to understand the processes responsible for these features. These simulations show that the large-scale asymmetry is related to salinity. The salt causes an estuarine circulation that decreases vertical mixing (vertical density gradient), increases longitudinal dispersion (increased vertical and lateral gradients in longitudinal velocities), and increases net downstream velocities in the surface layer. Since salinity intrusion is confined to the downstream end of the tracer plume, only that part of the plume is effected by those processes, which leads to the large-scale asymmetry. The small-scale peaks are due to tidal trapping. Small embayments along the estuary trap water and tracer as the plume passes by in the main channel. When the plume in the main channel has passed, the tracer is released back to the main channel, causing a secondary peak in the longitudinal profile.


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URL  <Go to ISI>://000222292500015