Accession Number:

ADA265911

Title:

Preliminary Analysis of the FLIP Array Data from the NOBS Experiment

Descriptive Note:

Technical memo.

Corporate Author:

SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB

Report Date:

1992-05-01

Pagination or Media Count:

87.0

Abstract:

Preliminary analysis of the data collected by the array suspended below RP FLIP FLoating Instrument Platform during the Noise Over Basalts and Sediments NOBS experiment are presented in this report. This report gives a description of the FLIP array, a summary of the tape log kept aboard FLIP, a summary of the quality of the data collected, and the results of some initial data analysis. The initial examination of the data shows that a total of 36 vertical line array VLA hydrophones and all four channels of four ocean bottom seismometers OBS provided useable data. The quality of the recorded data is variable, but remains rather high for extended periods of time, especially for the 10 hours of data on tape 7. Analysis of tape 7s data indicates that the calibrated ambient noise spectra estimated from the VLA hydrophones data agree well with predicted noise levels in moderate to heavy shipping regions. At times, these spectra contain a peak centered at 18 Hz, which is probably indicative of the presence of whales. In addition, ship-generated signals are clearly visible in the spectra at those times when surface ship sightings were noted in the experiment log. Finally, large amplitude signals of unknown origin were observed in the root mean squared RMS time series plots for all functioning data channels. The coherence function estimates between the OBS hydrophones and between the VLA hydrophones for the large arrivals are consistent with a horizontally propagating acoustic wave

Subject Categories:

  • Seismology
  • Marine Engineering
  • Acoustic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE