Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 105 (2014): 17-29, doi:10.1016/j.dsr2.2014.03.017.
Description:
In the summer of 2011, an oceanographic survey carried out by the Impacts of Climate
on EcoSystems and Chemistry of the Arctic Pacific Environment (ICESCAPE)
program revealed the presence of a massive phytoplankton bloom under the ice near
the shelfbreak in the central Chukchi Sea. For most of the month preceding the measurements
there were relatively strong easterly winds, providing upwelling favorable
conditions along the shelfbreak. Analysis of similar hydrographic data from summer
2002, in which there were no persistent easterly winds, found no evidence of upwelling
near the shelfbreak. A two-dimensional ocean circulation model is used to show that
sufficiently strong winds can result not only in upwelling of high nutrient water from
offshore onto the shelf, but it can also transport the water out of the bottom boundary
layer into the surface Ekman layer at the shelf edge. The extent of upwelling is
determined by the degree of overlap between the surface Ekman layer and the bottom
boundary layer on the outer shelf. Once in the Ekman layer, this high nutrient
water is further transported to the surface through mechanical mixing driven by the
surface stress. Two model tracers, a nutrient tracer and a chlorophyll tracer, reveal
distributions very similar to that observed in the data. These results suggest that the
biomass maximum near the shelfbreak during the massive bloom in summer 2011 resulted
from an enhanced supply of nutrients upwelled from the halocline seaward of
the shelf. The decade long trend in summertime surface winds suggest that easterly
winds in this region are increasing in strength and that such bloom events will become
more common.
Description:
This
study was supported by the National Science Foundation under Grant OCE-0959381 (MAS), and
by the Ocean Biology and Biogeochemistry Program and the Cryosphere Science Program of the
National Aeronautic and Space Administration under Award NNX10AF42G (RSP;KRA). GWKM
was supported by the Natural Sciences and Engineering Research Council of Canada. ETB was
supported by the U. S. Navy.
Keywords:
Upwelling
;
Boundary currents
;
Shelf-basin interaction
;
Phytoplankton blooms
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
