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Glider observations of enhanced deep water upwelling at a shelf break canyon: A mechanism for cross‐slope carbon and nutrient exchange
Author(s) -
Porter M.,
Inall M. E.,
Hopkins J.,
Palmer M. R.,
Dale A. C.,
Aleynik D.,
Barth J. A.,
Mahaffey C.,
Smeed D. A.
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012087
Subject(s) - upwelling , canyon , oceanography , geology , current (fluid) , pycnocline , geostrophic wind , hydrography , pressure gradient force , glider , geomorphology , meteorology , geography , marine engineering , engineering
Using underwater gliders we have identified canyon driven upwelling across the Celtic Sea shelf‐break, in the vicinity of Whittard Canyon. The presence of this upwelling appears to be tied to the direction and strength of the local slope current, which is in itself highly variable. During typical summer time equatorward flow, an unbalanced pressure gradient force and the resulting disruption of geostrophic flow can lead to upwelling along the main axis of two small shelf break canyons. As the slope current reverts to poleward flow, the upwelling stops and the remnants of the upwelled features are mixed into the local shelf water or advected away from the region. The upwelled features are identified by the presence of sub‐pycnocline high salinity water on the shelf, and are upwelled from a depth of 300 m on the slope, thus providing a mechanism for the transport of nutrients across the shelf break onto the shelf.