Ambient sound in the ocean induced by heavy precipitation and the subsequent predictability of rainfall rate
By: Charles C. McGlothin, Jr
Contributors: Naval Postgraduate School (U.S.). Department of Oceanography
Publisher: Naval Postgraduate School
Published: 1991
Place of publication: Monterey, California
Language: eng
Format: [electronic resource] /
Number of pages: 63
Subjects: Sound; Surfaces; Rain and rainfall; Clouds; Spectrum analysis; Storms; Ocean; Prophecies; Bays; Algorithms; Raindrops; Bubbles; Drops; Underwater acoustics
Description: An experiment was preformed in the Gulf Mexico to characterize the underwater sound generated by the heavy precipitation and to determine if rainfall rate can be measured using underwater sound. During this stage of the experiment, twenty-two data sets were recorded with rainfall rates up to 340 mm/ hr. For a given rainfall rate, it is found that sound levels from heavy convective precipitation are higher at the beginning of the storm and when rainfall rate is increasing than at the end of the storm event or when rainfall rates are decreasing. This may be due to changes in the drop size distribution during the life cycle of the storm or to variations in the temperature difference between the raindrop and the ocean surfaces. Very heavy rainfall generates near surface bubble layers or bubble clouds which attenuate sound energy at higher frequencies. The distinctive 15 kHz peak in the sound spectrum for light rain or absent during heavy rain suggesting that the sound production mechanism previously identified for small drops is suppressed by heavy rain even though those small drops are undoubtedly present during heavy rainfall rates. These data show a very high correlation between underwater sound level and the logarithm of the rainfall rate except when high wind speeds and high rainfall rates are present. An empirical rainfall rate algorithm for convective precipitation is proposed suggesting that sound energy is directly proportional to rainfall rate.
Notes: Thesis Advisor(s): Nystuen, Jeffrey A. ; Second Reader: Medwin, Herman.

June 1991.

Author(s) subject terms: Rainfall Rate, Underwater Sound Spectrum, Algorithm, Ambient Sound, Heavy Precipitation

Description based on title screen as viewed on May 16, 2011.

DTIC Descriptor(s): Algorithms, Bubbles, Clouds, Convection, Distribution, Drops, Energy, Frequency, Gulfs, High Rate, High Velocity, Layers, Level(Quantity), Life Cycles, Light, Mexico, Ocean Surface, Oceans, Particle Size, Precipitation, Predictions, Production, Rain, Raindrops, Rainfall, Rainfall Intensity, Rates, Sound, Spectra, Storms, Suppression, Surfaces, Underwater Sound, Wind Velocity.

DTIC Identifier(s): Oceans, Ambient Noise, Rainfall Intensity, Underwater Sound, Air Water Interactions, Acoustic Measurement, Wind Velocity, Theses, Mexico Gulf, Underwater Acoustics

US Navy (USN) author.

Thesis (M.S. in Physical Oceanography and Meteorology)--Naval Postgraduate School, June 1991.

Includes bibliographical references (p. 58-60).

Approved for public release, distribution unlimited--Cover.

Also available in print.

Mode of access: World Wide Web.

System requirements: Adobe Acrobat Reader.