The Alaskan Coastal Current

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The Alaskan Coastal Current

• Presented by Gerry Butrico

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The Alaskan Coastal Current

• Formed by storm systems associated with the
  Aleution Low
• Results in persistent cyclonic winds that impel
  onshore surface Ekman Transport and costal
  downwelling
• Year round current, trapped near the coast
• Forced by wind and buoyancy
• Most prominent circulation of the Gulf of
  Alaskas continental shelf

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The Alaskan Coastal Current

• Precipitation is a result of winds blowing over
  the mountains near the coast
• The coast is on the windward side of the
  Mountains
• Rainfall between 2-6 m/yr
• Wind stress and runoff have seasonal variability
• Wind is strong in winter, weak in summer

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The Alaskan Coastal Current

• Runoff is weak in the winter because most of the
  precipitation is stored as snow along the coast.
• Strongest during summer thaw and rain
• Runoff causes lower salinity near the surface
• Controls horizontal and vertical density
  gradients.

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The Alaskan Coastal Current

• Freshwater runoff flows on top of the denser salt
  water.
• The coriolis force, along with the coastal down
  welling caused by Ekman Transport causes the
  buoyant water to flow as a current

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The End

• Source Weingarther, Thomas J., Seth L.
  Dainelson, Thomas C. Royer, 2005 Freshwater
  variability and predictability in the Alaska
  Costal Current, Deep Sea Research II, 52, 169-191.