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The Hudson River Estuary
http://education.nationalgeographic.com/media/photos/000/283/28314.jpg
• Unusual hybrid of estuarine types
• Elements of fjord, salt-wedge and coastal plain estuaries
• Highly interactive with Hudson River
• Tides, Salinity, Density
• Partially mixed estuary
• Tide-induced mixing
• Salinity varies with season, spring/neap tides, and freshwater discharge
• Estuarine "salt wedge"
Estuarine Circulation
• Strong horizontal salinity and density gradients
• Creates a baroclinic pressure gradient
• Deep water driven landward by pressure gradient
• Surface water moves seaward due to surface slope
• Moves salt into estuary against river flow
• Stronger circulation with stronger gradients
• More vigorous circulation at high river flow
http://www.chesapeakequarterly.net/images/uploads/siteimages/CQ/V12N3/Estuarine-circulation_pritchard-large.png
Stratification• Partially Mixed estuary
• Closely related to amount of vertical mixing
• Dependent on difference between salinity in top and bottom layers
• Transport increases proportional to difference
• Drives physical exchange processes
• Biogeochemistry, ecology
• Most important factor in estuary classification
• Estuarine circulation strengthens stratification
http://www.ozcoasts.gov.au/indicators/images/salinity_structure.jpg
Tidal Influences• Major energy source in the estuary
• Mixes vertically, affects stratification• Affects estuarine circulation, which provides
the source of stratification
• Large spring-neap differences
• Generates turbulence
• Stronger stratification increases shear instability, suppresses turbulence
• Both cause mixing
• Tidal excursion: Distance a parcel of water is transported by tide in half a cycle
http://inhabitat.com/stacy-levys-tide-flowers-bloom-with-the-rising-waters-of-the-hudson-river/
New York Harbor Complex
• Flow is driven primarily by tidal straits• Sea level changes driven by tidal and
meteorological forcing• Two-layer flow is persistent, but not as
important• East River
• Tidal strait, not river• Connects to Long Island Sound• Among the strongest flows
• Kill Van Kull• Connects to Newark Bay• Effective at mixing water; tidal excursion
longer than strait• Arthur Kill
• Connects Raritan Bay to Newark Bay• Ineffective at mixing water; tidal
excursion shorter than strait• Raritan River and Passaic River major
freshwater inputs Geyer and Chant, 2006
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