Oceanography of the Gulf of Maine Physical Setting and the Circulation

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Oceanography of the Gulf of Maine- Physical
Setting and the Circulation
Pettigrew unpublished
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2 m
2002 2003
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Oceanography of the Gulf of Maine- Physical
Setting and the Circulation

• Large-scale Circulation
• Atmospheric Forcing
• Rivers
• Tides and Tidal Mixing

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Large-scale Circulation
Townsend, et al. 2004
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Flows INTO and OUT OF the Gulf of Maine
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2002 2003 2004
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2002 2003
2004
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Atmospheric Forcing
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Atmospheric Forcing- Interannual
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Rivers
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The North Atlantic Tidal Wave and Amphidromic
Point
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Trough of the North Atlantic Tidal Wave
Sweeping by the Gulf of Maine from North to
South... Water empties... (ebbing)
Crest of the North Atlantic Tidal Wave Sweeping
by.. (high tide) Water fills (flooding)
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Tidal Mixing

• The strong flows involved in tidal motions on the
  shelf induce large frictional stresses at the
  seabed which penetrate up the water column,
  inducing vigorous turbulent stirring.
• The shelf areas where tidal current exceeds 1 m/s
  experience the equivalent of a twice-daily
  hurricane!

Garret et al 1978
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Tidal Mixing Fronts- a sharp transition between
stratified and mixed regions
5 km, 1 oC/km
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Oceanography of the Gulf of Maine- Physical
Setting and the Circulation
Pettigrew unpublished
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Pettigrew et al., 1998
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Bay-Shelf Interactions
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Formation of fronts in the oceandue to buoyancy
fluxes
Hill, 1998
Spatial scales of 10s of kilometers or
less, Current speed 10 cm/s bounded by sharp
fronts
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Tidal Ellipse and Scales
Greenberg 1979
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Questions
Hoffman, 1998
One fish Nice here! Two fish Going with the
flow! Three fish Too cold, out of here!