Comment on “Abyssal upwelling and downwelling driven by near-boundary mixing”
Ledwell, James R.
MetadataShow full item record
KeywordAbyssal circulation; Boundary currents; Buoyancy; Diapycnal mixing; Mass fluxes/transport; Ocean circulation
McDougall and Ferrari have estimated the global deep upward diapycnal flow in the boundary layer overlying continental slopes that must balance both downward diapycnal flow in the deep interior and the formation of bottom water around Antarctica. The decrease of perimeter of isopycnal surfaces with depth and the observed decay with height above bottom of turbulent dissipation in the deep ocean play a key role in their estimate. They argue that because the perimeter of seamounts increases with depth, the net effect of mixing around seamounts is to produce net downward diapycnal flow. While this is true along much of a seamount, it is shown here that diapycnal flow of the densest water around the seamount is upward, with buoyancy being transferred from water just above. The same is true for midocean ridges, whose perimeter is constant with depth. It is argued that mixing around seamounts and especially midocean ridges contributes positively to the global deep overturning circulation, reducing the amount of turbulence demanded over the continental slopes to balance the buoyancy budget for the bottom and deep water.
Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 48 (2018): 739-748, doi:10.1175/JPO-D-17-0089.1.
Suggested CitationArticle: Ledwell, James R., "Comment on “Abyssal upwelling and downwelling driven by near-boundary mixing”", Journal of Physical Oceanography 48 (2018): 739-748, DOI:10.1175/JPO-D-17-0089.1, https://hdl.handle.net/1912/10363
Showing items related by title, author, creator and subject.
Spreading of Denmark Strait overflow water in the western subpolar North Atlantic : insights from eddy-resolving simulations with a passive tracer Xu, Xiaobiao; Rhines, Peter B.; Chassignet, Eric P.; Schmitz, William J. (American Meteorological Society, 2015-12)The oceanic deep circulation is shared between concentrated deep western boundary currents (DWBCs) and broader interior pathways, a process that is sensitive to seafloor topography. This study investigates the spreading ...
Perez-Brunius, Paula; Furey, Heather H.; Bower, Amy S.; Hamilton, Peter; Candela, Julio; García-Carrillo, Paula; Leben, Robert (American Meteorological Society, 2018-03-01)The large-scale circulation of the bottom layer of the Gulf of Mexico is analyzed, with special attention to the historically least studied western basin. The analysis is based on 4 years of data collected by 158 subsurface ...
Pedlosky, Joseph (American Meteorological Society, 2018-03-12)A simple oceanic model is presented for source–sink flow on the β plane to discuss the pathways from source to sink when transport boundary layers have large enough Reynolds numbers to be inertial in their dynamics. A ...