Forecasting the dispersal of the Hudson River Plume

John Wilkin (1), Gregg Foti (1) and Byoung-Ju Choi (2)

(1)IMCS, Rutgers University, New Brunswick, NJ
(2)COAS, Oregon State University, Corvallis, OR

The dispersal of the spring maximum discharge (freshet) of the Hudson River into the New York Bight and inner New Jersey shelf region is the focus of an integrated physical, biological and geochemical study employing a variety of observational systems (moorings, CODAR, autonomous gliders, ships, satellites) and forecast and hindcast modeling with ROMS.

A ROMS ocean prediction system using atmospheric forcing from the NCEP/NAM forecast and observed river flows was used to predict the dispersal of the spring freshet during the May 2005 intensive observing period. The trajectory of dye released in two Lagrangian tracer experiments was also forecast.

The dispersal of the freshwater anomaly associated with the plume was seen to be highly responsive to local winds on short time scales. Relatively little low salinity water immediately traveled southward along the New Jersey coast in a coastally trapped buoyancy driven current. A coastal current formed only with the assistance of favorable winds. The presence of the Hudson Shelf Valley exerts significant control on the overlying surface trapped plume, such that low salinity anomalies initially directed east along the Long Island, New York, coast were obstructed from joining any down-coast flow.