Transcript Ocean Bottom Topography

Ocean Bottom Topography
Ellen Martinsek
EPS 131
Wednesday, October 19
Outline
• Overview
• Bathymetry
• Examples of Features – A Ridge and A
Trench
• Significance to Ocean Circulation
• Conclusion
Bathymetry
• Definition: Measurement of water depth
• Techniques:
– Echo Soundings
– Satellite Altimetry
Mid-Atlantic Ridge
• Best-known and most-
studied example of a
divergent plate boundary
• Its discovery led to the
acceptance of the theory
of continental drift
Romanche Trench
• Third deepest of the major trenches of the
•
•
•
Atlantic Ocean (after Puerto Rice Trench and
South Sandwich Trench)
Dissects the Mid-Atlantic Ridge just north of the
equator
7,760 m deep; 300 km long; average width of 19
km
Allows for a major circulation of deep ocean
basin water from the west Atlantic to east
Atlantic basins: deep water flow W-E at a rate of
3.6x10^6 m^3/s of 1.57 degree C water
Beyond the Ocean Floor…
Sea level
Ocean Circulation
Roughness & Dissipation
Internal Waves
• Tidal energy is
•
converted to internal
waves generated by
tides flowing over
rough topography
Breaking internal
waves are nonlinear
enough that they
create locally
enhanced vertical
mixing
Vertical Mixing
Vertical mixing rates
are described in terms
of a diffusiivty
parameter, and vary
by more than THREE
ORDERS OF
MAGNITUDE in the
Brazil Basin in the
South Atlantic Ocean
Ocean Circulation
• Models have shown that ocean circulation
& oceanic heat transports are extremely
sensitive to variations in diffusivity…
• Equator-to-pole heat transport is a critical
component of the Earth’s climate system…
Sea Level
Conclusions
• Mixing
• Ocean circulation
• Climate
• Sea level
References
• Wikipedia http://en.wikipedia.org
• Gille, Sarah T., E J. Metzger, and Robin Tokmakian.
•
•
“Seafloor Topography and Ocean Circulation.”
Oceanography 17 (2003): 47-54. 15 Oct. 2005
http://tos.org
Jayne, Steven R., Louis C. St. Laurent, and Sarah T. Gille.
“Connections Between Ocean Bottom Topography and
Earth’s Climate.” Oceanography 17 (2004): 65-74. 15
Oct. 2005 http://tos.org
Knudsen, Per, and Ole B. Andersen. “Ocean bottom
topography from ERS-1 altimeter data.” ESA EOQ 51
(1996). 15 Oct. 2005
http://esapub.esrin.esa.it/eoq/eoq51/kor51.htm