BAMOS
Mar 2019
Figure 1: Schematic of how the current interacts with a shelf break canyon (Allen and Hickey, 2010).
This flow regime can cause two potential types of upwelling.
Firstly the cyclonic eddy formation can act to trap nutrients at
the top of the canyon causing the area around the head of the
shelf-break canyon to be nutrient-rich when an event occurs.
Depending on the speed of the upwelled current, and the
canyon’s steepness it is quite possible for multiple eddies to
form from one event (Pantoja et al., 2016) potentially influencing
the amount of nutrient entrapment occurring. References
The second potential form of upwelling is by the deeper current
being pushed up onto the shelf as this forms a topographical
Rossby Wave. These waves propagate to the right of the canyon
in the southern hemisphere (left in the northern hemisphere)
and can allow upwelling to occur at over 100 km away from the
canyon (Kämpf, 2012). This flow of nutrients however tends to
stay on the outside section of the shelf due to the rotation of
water particles remaining constant preventing it from pushing
that far into the shelf. Kämpf, J., 2007. On the magnitude of upwelling fluxes in shelf-
break canyons, Continental Shelf Research, 27, 2211–2223.
In conclusion a shelf-break canyon can be a vital part of the
ecosystem on the continental shelf. This is due to it being able
to upwell nutrients onto the shelf providing conditions allow for
it, and the canyon is cut into the shelf in a way that allows for it
to access deep water and have the flow in such a way that allows
for the formation of eddies, or topographical Rossby Waves.
Allen, S.E. and Hickey, B., 2010. Dynamics of advection‐driven
upwelling over a shelf break submarine canyon, Journal of
Geophysical Research: Oceans, 115.
Hickey, B.M., 1997. The response of a steep-sided, narrow canyon
to time-variable wind forcing, Journal of Physical Oceanography,
27, 697–726.
Kämpf, J., 2010. On preconditioning of coastal upwelling in the
eastern Great Australian Bight, Journal of Geophysical Research:
Oceans, 115.
Kämpf, J., 2012. Lee effects of localized upwelling in a shelf-
break canyon, Continental Shelf Research, 42, 78–88.
Pantoja, D.A., Marinone, S.G. and Filonov, A., 2016. Modeling the
Effect of a Submarine Canyon on Eddy Generation in Banderas
Bay, México, Journal of Coastal Research, 33, 564–572.
Rennie, S., Hanson, C., McCauley, R., Pattiaratchi, C., Burton,
C., Bannister, J., Jenner, C. and Jenner, M.-N., 2009. Physical
properties and processes in the Perth Canyon, Western Australia:
Links to water column production and seasonal pygmy blue
whale abundance. Journal of Marine Systems, 77, 21–44.
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