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Wind Sea behind a Cold Front and Deep Ocean Acoustics.
- Source :
-
Journal of Physical Oceanography . Jun2016, Vol. 46 Issue 6, p1705-1716. 12p. - Publication Year :
- 2016
-
Abstract
- A rapid and broadband (1 h, 1 < f < 400 Hz) increase in pressure and vertical velocity on the deep ocean floor was observed on seven instruments comprising a 20-km array in the northeastern subtropical Pacific. The authors associate the jump with the passage of a cold front and focus on the 4- and 400-Hz spectra. At every station, the time of the jump is consistent with the front coming from the northwest. The apparent rate of progress, 10-20 km h−1 (2.8-5.6 m s−1), agrees with meteorological observations. The acoustic radiation below the front is modeled as arising from a moving half-plane of uncorrelated acoustic dipoles. The half-plane is preceded by a 10-km transition zone, over which the radiator strength increases linearly from zero. With this model, the time derivative of the jump at a station yields a second and independent estimate of the front's speed, 8.5 km h−1 (2.4 m s−1). For the 4-Hz spectra, the source physics is taken to be Longuet-Higgins radiation. Its strength depends on the quantity , where F ζ is the wave amplitude power spectrum and I the overlap integral. Thus, the 1-h time constant observed in the bottom data implies a similar time constant for the growth of the wave field quantity behind the front. The spectra at 400 Hz have a similar time constant, but the jump occurs 25 min later. The implications of this difference for the source physics are uncertain. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00223670
- Volume :
- 46
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- Journal of Physical Oceanography
- Publication Type :
- Academic Journal
- Accession number :
- 116200530
- Full Text :
- https://doi.org/10.1175/JPO-D-15-0221.1