Iterative Method for the Estimation of Shot and Sea Floor Depths Using Hydrophone Streamer Data.
SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
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When explosive charges are used as sound sources in marine refraction experiments, a streamer hydrophone is often trailed near the surface by the vessel which launches the charges. The output of the streamer hydrophone is used to monitor the detonations, and after correcting for the time spent in traveling from the shot to the streamer hydrophone, provides a time origin for each shot. If three arrivals are present the direct water path and two reflections, then information about the shot depth and sea floor depth may also be obtained. Since the ship that launches the charges generally steams away from the drop site, incorrect results are obtained if vertical raypaths are assumed. In this report, a method which does not assume vertical raypaths is derived to find shot and sea floor depths. Inputs are the distance traveled from the drop site when the detonation first appears on the streamer hydrophone output, and the time differences between the three arrivals. A Fortran-77 program which implements the method is listed and its use is illustrated on data obtained during a refraction experiment conducted on the Monterey Deep-Sea-Fan.