Author: James Burgess Hagen
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ISBN:
Category : Ocean temperature
Languages : en
Pages : 360
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Simultaneous measurements of waves, orthogonal water particle velocities, temperature, conductivity and acoustic phase and amplitude measurements at 20 and 40 kHz over horizontal and vertical, 2m paths were made at the Navel Underwater Center oceanographic tower, San Diego in April 1974. Four stochastic models for acoustic propagation including geometric, Born, Rytov and Debye approximation models were tested. Taylor thermal microscales from spatial correlation analyses determined vertically across the thermocline varied from 6.8 to 178 cm. Temporal stochastic analyses showed horizontal acoustic path losses were ten times vertical losses because of diffraction effects.
Author: James Burgess Hagen
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ISBN:
Category : Oceanography
Languages : en
Pages :
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Author:
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Category :
Languages : en
Pages :
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Author: D. E. Weston
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Category :
Languages : en
Pages : 24
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Oscillations of up to 20 dB in level with total duration about 1 1/2 hours have been extensively seen in acoustic propagation experiments, and are due to internal waves. The transmission distances varied from 2 to 23 km in water 35 m deep, with frequency typically about 2 kHz. The internal waves and their acoustic effects were virtually switched on and off through the tidal cycle. This is due to the delicate and varying balance between the vertical density gradient and the shear gradient which together determine the Richardson number. The oceanographic structure was complicated, and included strong horizontal temperature gradients. For 1964 and 1965 experiments in the eastern part of the working area the effects tended to occur near slack water (+ 2 hours relative to local high water) with periods of about 5 min and wavelengths apparently about 50 m. For 1967-1969 experiments in the western part the effects tended to occur near times of maximum flow ( -1 and +5 hours) with periods of about 20 min and wavelengths apparently about 500 m. Measurements from five other indicators of internal waves are included. (Author).
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Category : Aeronautics
Languages : en
Pages : 456
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
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Category : Weights and measures
Languages : en
Pages : 838
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Author:
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ISBN:
Category : Military oceanography
Languages : en
Pages : 498
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Author:
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ISBN:
Category : Military oceanography
Languages : en
Pages : 496
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Author: United States. Navy Symposium on Military Oceanography
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Category : Military oceanography
Languages : en
Pages : 502
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Author:
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ISBN:
Category : Science
Languages : en
Pages : 930
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