Accession Number : ADA300309

Title :   High-Frequency Surface-Scattering Measurements During the FLIP Experiment.

Descriptive Note : Technical rept.,

Corporate Author : WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB

Personal Author(s) : Dahl, Peter H.

PDF Url : ADA300309

Report Date : SEP 1995

Pagination or Media Count : 30

Abstract : Several kinds of high-frequency surface-scattering measurements and environmental sea-state measurements were made from the research platform FLIP in January 1992. Data from this experiment continue to be used in the research and development of models that predict performance of high-frequency sonar systems. This report summarizes results of sea-surface-backscattering measurements obtained over the frequency range 20-50kHz and the grazing-angle interval 1 to 15 deg. for wind speeds between 1 and 10 m/s. This low-grazing-angle interval represents an important gap in our database of sea-surface-backscattering strength used in modeling. One data set was also obtained over the grazing-angle interval 35-55 deg. during which the wind speed was 4.6 m/s. The data compare reasonably well with the APL-UW surface-backscattering model for the frequency range 25-40 kHz. At 20 and 50 kHz, however the data are consistently lower (by 2-4 dB) than the model. A bias in the 20- and 50-kHz data, which is associated with the frequency response of the transducer system, is strongly suspected. Overall, the model fits the FLIP data to within a mean error (for the model-minus-data vector) of 1.7 dB and a standard deviation of 2.7 dB. When the 20- and 50-kHz data are corrected for bias, the mean error is reduced to 0.8 dB.

Descriptors :   *OCEAN SURFACE, *BACKSCATTERING, *ACOUSTIC SCATTERING, DATA BASES, MATHEMATICAL MODELS, HIGH FREQUENCY, COMPARISON, ACOUSTIC MEASUREMENT, WIND VELOCITY, CALIBRATION, AIR WATER INTERACTIONS, BIAS, REVERBERATION, UNDERWATER ACOUSTICS, SEA STATES, ACOUSTIC DATA, SOUND PRESSURE, SONAR TRANSDUCERS, FREQUENCY RESPONSE, SONAR ARRAYS, GRAZING ANGLES.

Subject Categories : Acoustics
      Physical and Dynamic Oceanography
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE