摘要:

Research conducted by the Naval Research Laboratory in low‐frequency, long‐range underwater reverberation has led to an acoustic operation and processing technique that is applicable to basin‐wide bathymetric surveying. The technique uses 23‐kg explosive sources and a commercial seismic array receiver to obtain topographic reverberation data covering radial distances of more than 500 nautical miles (NM). After filtering and beam forming, the processing provides spatial stabilization of beams and averaging over multiple shots to correct for left‐right ambiguities. The resulting product is a plot of the locations of major topographic reverberators over entire basin areas. The processing technique has been applied to data collected in two tests conducted in a Pacific basin northeast of New Zealand. Processing and averaging of more than 200 explosive shots from each test produced maps covering more than 1 million sq NM. In addition to identifying the locations of all major known topographic features, the reverberation maps showed the existence of new features which were subsequently verified by depth sounding. The paper presents design criteria for future applications to other areas. The reverberation mapping technique could eventually be developed into an on‐board system that would survey entire basin areas in one week's time.

ISSN:0149-0419    

DOI:10.1080/01490418609388008

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The paper presents a description of statistical characteristics of complex geographical positioning methods of oceanographic measurement, based on the application of global navigational systems. These characteristics can be used to evaluate minimum discreteness between independent coordinates as well as for comparison of different methods in their rate of error accumulation between observations.

ISSN:0149-0419    

DOI:10.1080/01490418609388009

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper proposes the use of change‐in‐phase measurements of a multiple‐satellite‐tracking NAVSTAR Global Positioning System (GPS) receiver and an antenna periodically moving in a platform's plane to determine the platform's orientation. Available test data are used to demonstrate the orientation‐determination capability of GPS using the proposed procedure. The expected accuracy using satellite multiplexing receivers currently completing development is also discussed.

ISSN:0149-0419    

DOI:10.1080/01490418609388010

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The altimeter data from the three‐day repetitive period of Seasat are processed in order to detect the zonal slope variability in the Indian Ocean from mid‐September to mid‐October 1978. This processing illuminates problems due to contamination in the topographic signal caused by geoid and orbit errors. When all spurious effects are eliminated, a residual variability is obtained that compares reasonably well with the expected oceanographic signal

ISSN:0149-0419    

DOI:10.1080/01490418609388011

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A technique is currently under development a the Naval Research Laboratory for imaging of backscatterec acoustic returns from ocean basin topography. The method is straightforward. An explosive sound source is detonated near the center of an ocean basin and the round‐trip travel time from source to reflectors and return is measured. Distance to back‐scattering topography is assumed to be proportional to round‐trip time, with a proportionality constant equal to half the sound speed. A multielement receiving array is used to determine the azimuthal directions to topographic features. Reverberation data are output to an imaging system to study the spatial distribution of sea bottom reverberation. The images are in the form of two‐dimensional maps of backscattered acoustic energy. Typical maps are larger than 2,000 km x 2,000 km (or area coverage greater than 4 x 106km2). After correction of maps from individual shot detonations for range‐dependent propagation losses, we average ("integrate") maps together on a pixel by pixel basis for a clear picture of major basin reverberators.

ISSN:0149-0419    

DOI:10.1080/01490418609388012

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

J. M. Bishop,Applied Oceanography,a Wiley‐Interscience Publication (New York: John Wiley & Sons, 1984), 252 pp., $32.95.

ISSN:0149-0419    

DOI:10.1080/01490418609388013

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/01490418609388014

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/01490418609388007

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor