A METHOD OF AIRBORNE BOTTOM-REFLECTIVITY SURVEYING,

Abstract : The acoustic reflectivity of the ocean bottom has been measured by means of sonobuoys and standard Navy explosive sound signals dropped from an aircraft. Charges were dropped at distances up to 10 miles from a modified AN/SSQ-23 sonobuoy to give data at various grazing angles. Drops were made at 85 widely spaced locations in the Atlantic westward from Bermuda on 5 aircraft operating days, including drops for comparison purposes in OPEVAL Areas A, B and C, where bottom reflectivity had previously been measured by the Oceanographic Office. The tape recordings made aboard the aircraft were later filtered, squared, and integrated to give the energy reflection coefficients of the bottom. The method appears to have merit as a means of rapid, mobile and inexpensive acoustic surveying. (Author)