Role of shelfbreak upwelling in the formation of a massive under-ice bloom in the Chukchi Sea
Spall, Michael A.
Pickart, Robert S.
Brugler, Eric T.
Moore, G. W. K.
Thomas, Leif N.
Arrigo, Kevin R.
MetadataShow full item record
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.
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.
Showing items related by title, author, creator and subject.
The Atlantic Water boundary current in the Nansen Basin : transport and mechanisms of lateral exchange Våge, Kjetil; Pickart, Robert S.; Pavlov, Vladimir; Lin, Peigen; Torres, Daniel J.; Ingvaldsen, Randi B.; Sundfjord, Arild; Proshutinsky, Andrey (John Wiley & Sons, 2016-09-22)Data from a shipboard hydrographic survey near 30°E in the Nansen Basin of the Arctic Ocean are used to investigate the structure and transport of the Atlantic Water boundary current. Two high-resolution synoptic crossings ...
Loose, Brice; Jenkins, William J.; Moriarty, Roisin; Brown, Peter; Jullion, Loic; Naveira Garabato, Alberto C.; Valdes, Sinhue Torres; Hoppema, Mario; Ballentine, Chris; Meredith, Michael P. (John Wiley & Sons, 2016-08-18)The distribution of noble gases and helium isotopes in the dense shelf waters of Antarctica reflects the boundary conditions near the ocean surface: air-sea exchange, sea ice formation, and subsurface ice melt. We use a ...
Barth, John A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1987-10)A two-layer shallow water equation model is used to investigate the linear stability of a coastal upwelling front. The model features a surface front near a coastal boundary and bottom topography which is an arbitrary ...