Transporting sediment off of the continental shelf
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This page first made public: Apr 20, 2017
In this activity students examine a map of geopotential anomaly to determine ocean current patterns. They then examine particle beam attenuation data to identify patterns in the locations of intermediate nepheloid layers over the continental slope. Finally, they are asked to describe the processes that account for those patterns.
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Description and Teaching Materials
Student handout for off shelf sediment transport (Microsoft Word 2007 (.docx) 354kB Apr20 17)
Teaching Notes and Tips
Be prepared with a clear description of bottom Ekman veering. This is a nice follow on from the concept of geostrophic flow. Near the sea floor friction slows the current. This reduces the Coriolis force, since it is proportional to current speed. As a result the current turns in the direction of the pressure gradient. Since the pressure gradients in the cyclone and in Eddy Vasquez are in opposite directions, flows and sediment transport are in opposite directions. The onshore flow associated with Eddy Vasquez carries clear, slope water. The offshore flow associated with the cyclone carries the shelf bottom nepheloid layer out into slope waters.
A short discussion of particle bean attenuation coefficient may be necessary. It is sufficient to say that low values correlate with low suspended sediment concentrations and vice versa.
References and Resources
This link gives an explanation of geostrophic currents