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Lunar and Solar Torques on the Oceanic TidesBrosche and Seiler recently suggested that direct lunar and solar tidal torques on the oceanic tides play a significant role in the earth's short-period angular momentum balance ("short-period" here meaning daily and sub-daily). We reexamine that suggestion here, concentrating on axial torques and hence on variations in rotation rate. Only those spherical harmonic components of the ocean tide having the same degree and order as the tidal potential induce nonzero torques. Prograde components (those moving in the same direction as the tide-generating body) produce the familiar secular braking of the earth's rotation. Retrograde components, however, produce rapid variations in UTI at twice the tidal frequency. There also exist interaction torques between tidal constituents, e.g. solar torques on lunar tides. They generate UTI variations at frequencies equal to the sums and differences of the original tidal frequencies. We give estimates of the torques and angular momentum variations for each of the important regimes, secular to quarter-diurnal. For the M(sub 2) potential acting on the M(sub 2) ocean tide, we find an associated angular momentum variation of amplitude 3 x 10(exp 19) N m. This is 5 to 6 orders of magnitude smaller than the angular momentum variations associated with tidal currents. We conclude that these torques do not play a significant role in the short-period angular momentum balance.
Document ID
19990099278
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ray, Richard D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Bills, Bruce G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Chao, Benjamin F.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Subject Category
Oceanography
Meeting Information
Meeting: 1998 American Geophysical Union Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 6, 1998
End Date: December 10, 1998
Sponsors: American Geophysical Union, American Geophysical Union, American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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