Salt flux into coastal river plumes: Dye studies in the Delaware and Hudson river outflows

R. W. Houghton, R. J. Chant, Ana Rice, Charles Tilburg

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The results of ten dye tracer experiments conducted in 2003-2006 to study the dispersion of the outflow of the Delaware and Hudson Rivers are presented. A fluorescent dye tracer was used to track the river plume and to measure directly the salt flux into the plume. A variety of flow regimes were encountered. During strong upwelling events, a salt flux of ~3 ÷ 10-4 kg m s-1 at the leading edge of the plume implies a vertical diffusivity of Kz ~ 3 × 10-4 m-2 s-1. Comparable salt flux was measured at the leading edge of a buoyancy-driven coastal current with Kz ~ 6.3 × 10-4 m-2 s-1. For weaker wind events Kz was ≤10-4 m-2 s-1. Using a gradient Richardson number (Ri), these observations were replicated by a 1-D model of vertical salt flux to within a factor of 2. Upwelling events are the most efficient mechanism for dispersing the river plume water over the coastal shelf because the plume's offshore displacement is combined with a horizontal diffusivity measured to be ~150 m-2 s-1 over the two-day period of each experiment.

Original languageEnglish (US)
Pages (from-to)731-756
Number of pages26
JournalJournal of Marine Research
Issue number6
StatePublished - Nov 2009

All Science Journal Classification (ASJC) codes

  • Oceanography


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