Accession Number : ADA625649


Title :   Seabed Scattering from Low Frequency Reverberation Measurements


Descriptive Note : Final technical rept. Oct 2010-Sep 2015


Corporate Author : GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING


Personal Author(s) : Zhou, Ji-Xun ; Zhang, Xue-Zhen


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a625649.pdf


Report Date : 30 Sep 2015


Pagination or Media Count : 49


Abstract : Low-frequency (LF) seabed scattering at low grazing angles (LGA) is almost impossible to directly measure in shallow water (SW), except through inversion from reverberation. The energy flux method for SW reverberation is briefly introduced in this paper. The closed-form expressions of reverberation in an isovelocity waveguide, derived from this method, indicate that in the threehalves law range interval multimode/ray sea bottom scattering with different incident and scattering angles in forming the reverberation may equivalently be represented by the bottom backscattering at a single range-dependent angle. This equivalent relationship is used to derive the bottom backscattering strength (BBS) as a function of angle and frequency. The LF&LGA BBS is derived in a frequency band of 200 2500 Hz and in a grazing angle range of 1.1 deg 14.0 deg from reverberation measurements at three sites with sandy bottoms.


Descriptors :   *GRAZING ANGLES , *LOW FREQUENCY , *OCEAN BOTTOM , *SCATTERING , BACKSCATTERING , FREQUENCY BANDS , REVERBERATION , SHALLOW WATER , WAVEGUIDES


Subject Categories : Theoretical Mathematics
      Radiofrequency Wave Propagation


Distribution Statement : APPROVED FOR PUBLIC RELEASE