HR: 16:00h
AN: OS52L-07    [PDF]
TI: Remote Wind-Driven Overturning Without the Drake Passage
AU: * Klinger, B A
EM: klinger@cola.iges.org
AF: George Mason University, 4400 University Drive, MS 5C3, Fairfax, VA 22030 United States
AU: Drijfhout, S
EM: drijfhou@knmi.nl
AF: Royal Netherlands Meterological Institute, PO Box 201, 3730 AE, de Bilt, Netherlands
AU: Marotzke, J
EM: marotzke@dkrz.de
AF: Max Planck Institute for Meteorology, Bundesstr. 55, Hamburg, Germany
AU: Scott, J R
EM: jscott@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Avenue Bldg 54, Cambridge, MA 02139 United States
AB: Zonal windstress over the Southern Ocean may be responsible for a significant fraction of the meridional overturning associated with North Atlantic Deep Water. This remote, wind-driven overturning is associated with the zonal periodicity of the Southern Ocean: the ``Drake Passage Effect'' (Toggweiler and Samuels, 1995). Numerical experiments by Tsujino and Suginohara (1999) imply that the zonal periodicity of the Southern Ocean is not necessary for midlatitude westerly winds to drive strong remote meridional overturning. Their results raise questions concerning the fundamental dynamics of the wind-driven overturning, and also show an apparent discrepancy with similar experiments of Klinger {\em et al.} (2003). Here, idealized numerical experiments examine the importance of zonal periodicity and other factors in setting the sensitivity of this overturning to the windstress. Seemingly minor differences in configuration account for the discrepancy noted above. The new experiments support the conclusion that the wind can drive remote overturning in the absence of zonal periodicity. However, making the subpolar ocean zonally periodic roughly doubles the strength of the overturning induced by the wind there. How is overturning driven far from the location of wind forcing? Tsujino and Suginohara suggested that wind increases the overturning by enhancing the mixing-driven thermohaline circulation. However, an increase in thermohaline circulation is associated with increased conversion of turbulent kinetic energy to potential energy. This increase in the energy conversion is absent in the wind-driven case, indicating an important qualitative difference between mixing-driven thermohaline overturning and remote wind-driven overturning.
UR: http://www.iges.org/people/klinger.html
DE: 4255 Numerical modeling
DE: 4279 Upwelling and convergences
DE: 4283 Water masses
DE: 4532 General circulation
DE: 9325 Atlantic Ocean
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting