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Tidal Energy Available for Deep Ocean Mixing: Bounds from Altimetry DataMaintenance of the large-scale thermohaline circulation has long presented an interesting problem. Observed mixing rates in the pelagic ocean are an order of magnitude too small to balance the rate at which dense bottom water is created at high latitudes. Recent observational and theoretical work suggests that much of this mixing may occur in hot spots near areas of rough topography (e.g., mid-ocean ridges and island arcs). Barotropic tidal currents provide a very plausible source of energy to maintain these mixing processes. Topex/Poseidon satellite altimetry data have made precise mapping of open ocean tidal elevations possible for the first time. We can thus obtain empirical, spatially localized, estimates of barotropic tidal dissipation. These provide an upper bound on the amount of tidal energy that is dissipated in the deep ocean, and hence is available for deep mixing. We will present and compare maps of open ocean tidal energy flux divergence, and estimates of tidal energy flux into shallow seas, derived from T/P altimetry data using both formal data assimilation methods and empirical approaches. With the data assimilation methods we can place formal error bars on the fluxes. Our results show that 20-25% of tidal energy dissipation occurs outside of the shallow seas, the traditional sink for tidal energy. This suggests that up to 1 TW of energy may be available from the tides (lunar and solar) for mixing the deep ocean. The dissipation indeed appears to be concentrated over areas of rough topography.
Document ID
19990114316
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ray, Richard D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Egbert, Gary D.
(Oregon State Univ. Corvallis, OR United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Oceanography
Meeting Information
Meeting: TOPEX/POSEIDON-JASON SWT meeting
Location: Saint Raphael
Country: France
Start Date: October 25, 1999
End Date: October 27, 1999
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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