ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
4pUW3. Preliminary comparisons between bistatic reverberation from an
ocean ridge and wavelength-scale geomorphology.
Nicholas C. Makris
Lilimar Avelino
Richard Menis
Naval Res. Lab., Washington, DC 20375
Bistatic reverberation measured from a highly lineated ridge in the
mid-Atlantic during the ARSRP Main Acoustics Experiment of 1993 was compared
with bottom slope orientation determined from 200-m resolution Hydrosweep
bathymetry in a previous abstract [Makris et al., 3329(A) (1994)]. It
was found that prominent returns register with extended scarps facing the
source and receiving array. These scarps typically extend for lengths greater
than 1 km and have widths that are less than 1 km. However, the hydrosweep
bathymetry is not of sufficient resolution to determine the fine-scale
geomorphology of the scarps, and leads to slope estimates (20(degrees) to
30(degrees)) that are a severe underestimate. Fine-scale bathymetry of 5-m
resolution recently obtained for the same ridge shows that the scarps returning
prominent reverberation generally contain cliff faces with slopes between
60(degrees) to 90(degrees). However, the separation between these cliff faces
is typically less than the roughly 500-m cross-range resolution of the
towed-array imaging system. An attempt is made to resolve individual cliff
faces with remote returns measured at 1/2 CZ by exploiting the much higher
range resolution of the towed-array imaging system (which approaches roughly 10
m) and examining differently oriented bistatic measurements of the same sites.