Mid-Atlantic BightTransport over a Long Shallow Shelf

~ 25m depth at the inner shelf

~ 50m at midshelf~ 200m at the shelf

break, where it then drops rapidly to deep ocean

(1 Degree Longitude ~ 85.4km @ 40N)

The distance shore to shelf break ranges from 60-200km

The Shelf

Estuaries of the MAB

Chesapeake Bay systemDelaware BayHudson River

Winter Conditions

Summer Conditions

(Immediately before and during Irene)

Ekman vs TilburgUnconventional Upwelling

Tilburg's ModelK_M - vertical eddy viscosityK_H - vertical eddy diffusivity

Density taken from the Equation of State

Salinity is constantHorizontal eddy viscosity and

diffusivity are constant

K_M terms calculated for surface wind stress and bottom stress given by D

L= 65km (width of shelf)

Downwelling and Onshore Transport - Ekman

Downwelling and Onshore Transport - Tilburg

Transport in 3 Dimensions - Wind Stress

Wind Stress is the primary mechanism for transport.

Integrated continuity equation can be used to demonstrate the surface and bottom stress is directly related to across shore transport while inversely related to along shore divergence.

Transport in 3 Dimensions - Buoyancy as an amplifierShallow Shelf allows for fresh water intrusions to

reach the bottom instead of forming a lens.Supports geostrophic, cyclonic flow of high

downshelf velocity.High shear across shore.These intrusions become displaced offshore and

mix while the region experiences upwelling at the coast.

Transport in 3 Dimensions - Buoyancy as an amplifierThe buoyancy intrusion's flow is driven by stratification gradients (dN^2/dy) creating velocity gradients along shore.

Negative gradient indicates convergence with the intrusion upshelf.Positive gradient indicates divergence with the intrusion downshelf.

While wind dominates the buoyancy intrusion under strong wind conditions, divergence may still be strong under light wind conditions.

Across-Shelf Transport on a Continental Shelf: Do Across-Shelf Winds Matter?

Tilburg 2003

Three-Dimensional Flow in a Shallow Coastal Upwelling Zone: Alongshore

Convergence and Divergence on the New Jersey ShelfTilburg and Garvine 2003

Additional Images from:RUCOOL glider page

http://cmtt.tori.org.tw/data/App_map/Maps_jpg/4_13_Mid_Atlantic_Bight_New_York_Bight.jpg

http://ocw.mit.edu/resources/res-12-000-evolution-of-physical-oceanography-spring-2007/part-1/wunsch_chapter7.pdf

References