Message in a Bottle

1
Message in a Bottle

• A satellite journey through the Gulf Stream

2
Overview of Presentation

• The historical message and importance of the Gulf
  Stream
• The path of the global surface currents
• A look at the concepts of formation of ocean
  gyres, and special features
• Discussion of the formation, properties and
  position of the eddies

3
The Message

• Historical Importance
• Exploration and Trade provided navigational
  knowledge of the North Atlantic Gyre

4
The Message

• Historical Importance
• Ben Franklins map of fastest route across the
  Atlantic based on his voyage measurements of 1775
  - 1785

5
The Message

• Historical Importance
• U.S. Coast and Geodetic Survey map (1890) showing
  the North Wall --the edge of this western
  boundary current

6
The Path

• Tracking the Floaters

• Glass fishing floats, sneakers and toys become
  tools to measure currents
• Carried across the Pacific by the strong
  Kuroshio current

7
The Path

• Global surface currents are the result of wind
  driven force
• Moving water is deflected like the air by the
  Coriolis effect
• The denser water is deflected more than the above
  air

8
The Path

• Tracking the Floaters

• Path of water is influenced by global wind bands
  Trades and Westerlies
• Friction slows the deflected water throughout a
  depth of about 150 meters

9
The Path

• Tracking the Floaters

• Current path is also affected by landforms
• Gulf Stream turns sharply to the east off Cape
  Hatteras, NC

10
The Path

• Tracking the Floaters

• Drift bottles deployed in the Gulf of Mexico and
  the Caribbean have been followed by satellites
• Data explains current motion

YOTO floats
11
What does this drifter path tell you about the
direction of the Gulf Stream?
12
Major Oceanic surface currents
13
The Understanding

• Special features

• Origins in the Gulf of Mexico and waters merge
  with Caribbean currents
• Travels around the Straits of Florida parallel to
  East coast

There is a river in the ocean Mathew Maury,
1855
14
The Understanding

• Special features

• Carries heat energy toward the continent of
  Europe
• Some surface water becomes cooler, more saline
  and sinks near Norway

15
The Understanding

• Special features

• Gulf Stream water temperatures are substantially
  warmer than the waters to the North
• Act as a barrier between Sargasso Sea and North
  Labrador current

16
The Understanding

• Gulf stream water temperatures are significantly
  warmer down to depths of 1000 meters

17
The Understanding

• Volume of water transported is from 55 to 106
  cubic meters per second
• Current velocity is dependent on the width and
  depth of current

18
The Understanding

• Special features

• Geostrophic balance exists in the N. Atlantic as
  the Coriolis effect piles water into a bulge (
  Sargasso Sea) that gravity carries downhill

19
The Understanding

• Differences in sea height are seen with satellite
  altimetry
• Pockets of warm or cold water may be trapped

20
The Science Twist

• Unique meanders

• Gulf stream energy is diverted by changes in
  speed
• Eddies form -- rotating pockets that spin off the
  main stream

21
The Science Twist

• Unique meanders

• Warm- core eddies are found usually to the north
  of the north wall
• Spin clockwise
• WCR Warm core rings

22
The Science Twist

• Unique meanders

• Cold- core eddies are found to the south of the
  Gulf Stream
• Spin counterclockwise
• Migrate into the Sargasso Sea

23
The Science Twist

• Unique meanders

• Warm water expands and is noticed by a bulge in
  the sea surface
• Cold water eddies are detected by a depression

24
The Science Twist

• Mesoscale eddies are 50-100 km in diameter
• WCR drift back into Gulf Stream
• Cold eddies may last several years

25
The Science Twist

• Unique meanders

• In the Gulf of Mexico, eddies are studied for
  their influence on hurricanes
• Hurricane Opal and Bret were fueled by WCRs

26
Message in a Bottle

• Describe several factors that determine the flow
  of the Gulf Stream?
• What is the direction of flow of the worlds
  major ocean currents?
• What is the relationship between heat transport
  and the eddies?