Publication Date:
2022-05-26
Description:
Also published as Reviews of Geophysics and Space
Physics, Vol. 15, No. 4, November 1977, pp. 385-420
Description:
From moored data, primarily temperature, of the Mid-Ocean Dynamics Experiment (ModeI) and its
successor experiments we find a statistical description of the mesoscale variability. In the ModeI area
itself the spectral characteristics of the thermocline and the deep water are different. The thermocline is
conveniently described as being made up of three spectral bands: a ' low-frequency' band dominated by
zonal velocity fluctuations, an 'eddy-containing' band in which the velocity field is nearly isotropic, and a
'high-frequency' band consistent with models of geostrophic turbulence. In the deep water the zonal
dominance at low frequencies is not apparent, and there is enhanced energy at periods of 20-50 days.
Vertical structure scales with WK BJ approximation in the high-frequency band but not in the lower
frequencies, where low vertical modes dominate the motion. Linear models do not adequately describe the
data in the ModeI region. Differences between rough and smooth topography regions are clearly seen
only at 1500 m, where there is a loss of energy consistent with a reduced barotropic motion. Other
differences, while apparently real, are small. It is found, consistent with the results of Schmitz (1976a),
that the ModeI region is atypical of the midocean in that large changes of energy level are found
elsewhere. A region due east of ModeI has slightly reduced kinetic energy levels in the main thermocline,
but deep energy levels are much lower. Potential energy is less variable than kinetic; in the eastern region
the frequency spectra change structure slightly. Linear models may be more adequate there. With more
than 2 years of data, no statistically significant heat flux was found in the ModeI area, except for a weak
zonal flux in the deep water. There is no direct evidence for baroclinic instability as a significant
mechanism of eddy generation; the Gulf Stream is a possible, if unconfirmed, source.
Description:
Prepared for the Office of Naval Research under
Contracts N00014-66-C-0241; NR 083-004~
N00014-74-C-0262; NR 083-004 and N00014-76-C-0197;
NR 083-400; and for the National Science Foundation
under Grants GX-29054, GX-29034, OCE 75-03962 and
ID0-82534.
Keywords:
Ocean temperature
;
Thermoclines
Repository Name:
Woods Hole Open Access Server
Type:
Technical Report
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