Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 84 (2014): 110-126, doi:10.1016/j.dsr.2013.10.007.
Description:
Data from seven moorings deployed across the East Greenland shelfbreak and slope 280 km
downstream of Denmark Strait are used to investigate the characteristics and dynamics
of Denmark Strait Overflow Water (DSOW) cyclones. On average, a cyclone passes the
mooring array every other day near the 900 m isobath, dominating the variability of the
boundary current system. There is considerable variation in both the frequency and location
of the cyclones on the slope, but no apparent seasonality. Using the year-long data set from
September 2007 to October 2008, we construct a composite DSOW cyclone that reveals the
average scales of the features. The composite cyclone consists of a lens of dense overflow
water on the bottom, up to 300 m thick, with cyclonic flow above the lens. The azimuthal
flow is intensified in the middle and upper part of the water column and has the shape of a
Gaussian eddy with a peak depth-mean speed of 0.22 m/s at a radius of 7.8 km. The lens
is advected by the mean flow of 0.27 m/s and self propagates at 0.45 m/s, consistent with
the topographic Rossby wave speed and the Nof speed. The total translation velocity along
the East Greenland slope is 0.72 m/s. The self-propagation speed exceeds the cyclonic swirl speed, indicating that the azimuthal flow cannot kinematically trap fluid in the water column
above the lens. This implies that the dense water anomaly and the cyclonic swirl velocity
are dynamically linked, in line with previous theory. Satellite sea surface temperature (SST)
data are investigated to study the surface expression of the cyclones. Disturbances to the
SST field are found to propagate less quickly than the in-situ DSOW cyclones, raising the
possibility that the propagation of the SST signatures is not directly associated with the
cyclones.
Description:
Funding for the study was provided by National Science Foundation Grant OCE-0726640 and the Arctic Research Initiative of the Woods Hole Oceanographic Institution.
Keywords:
Denmark strait overflow water cyclone
;
East greenland boundary current system
;
East greenland spill jet
;
Deep western boundary current
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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