摘要:

Various scanning configurations for laser‐based airborne hydrography are examined to assess the implications of each in establishing an accurate reference against which sea depths may be measured. A configuration in which an infrared laser beam is scanned and co‐directional with a green laser beam is found to give a significantly poorer estimation of mean sea surface location than configurations incorporating a fixed vertical wide divergence infrared beam. Furthermore, configurations that use the leading edge of sea subsurface backscatter to give estimates of local sea surface location are shown to be seriously susceptible to variations in the magnitude of that backscatter.

ISSN:0149-0419    

DOI:10.1080/15210608809379572

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The practice of measuring depths and positions at sea has traditionally been divided into hydrography and bathymetry. NOAA's National Ocean Service (NOS) is at the forefront of a technological revolution that is causing the distinctions between these disciplines to blur and disappear. A unified marine geographic information system is emerging.

ISSN:0149-0419    

DOI:10.1080/15210608809379573

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The U.S. Geological Survey (USGS) started a program in April 1984 to map the deep‐water (greater than 200 m) areas of the U.S. Exclusive Economic Zone (EEZ) at a reconnaissance scale as a first effort to develop a geologic understanding of the new national offshore territory. This effort was in response to President Reagan's EEZ proclamation in March 1983, which extended U.S. jurisdiction over an area extending 200 nautical miles offshore of the United States and U.S. trust territories. This USGS mapping effort is a cooperative effort with the Institute of Oceanographic Sciences (IOS) of the United Kingdom and uses a unique side‐scan sonar system named GLORIA (Geological Long‐Range Inclined Asdic) developed by IOS. To date, over 3,500,000 km2have been mapped off the west coast, the east coast, the Island of Hawaii, Puerto Rico, and the U.S. Virgin Islands and in the Gulf of Mexico and the Bering Sea. All of these surveys have been highlighted by discoveries of major geologic features that contribute to our understanding of basic geologic principles and processes, composition and character of marine rocks/ sediments, and assessment of nonliving marine resources and geohazards. This program provides “roadmaps”; and “guideposts”; for subsequent, more detailed studies of specific features or areas. A compilation of the processed sonographs, with overlays of bathymetry and geologic interpretations, as well as other types of data (e.g., magnetics and high‐resolution seismic data), is published in an atlas for each survey area at a scale of 1:500,000. To date, the west coast and Gulf of Mexico/Puerto Rico/American Virgin Island data have been published. Results of the Bering Sea and east coast surveys will be published in 1988.

ISSN:0149-0419    

DOI:10.1080/15210608809379574

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Some of the factors affecting the accuracy of positioning with the OMEGA radionavigation system are discussed. A simplified algorithm of computing the diurnal corrections for OMEGA is developed. It is based on the calculation of the mean velocity of propagation of VLF radiowaves as a function of the effective height of a spherical waveguide. The formulae to compute the latter are given. A composite signal method proposed by Pierce and its modification by Papousek and Reder are discussed; it is shown that the accuracy of the modified version is not better than that of the original. Both in Pierce's method and its modifications the waveguide is treated as a plane. Its sphericity is taken into account in this article, which results in better compensation of the phase variations of OMEGA signals. It is shown that fractionally rational transformations of the phase count may result in an additional error. To reduce that error, a high reliability of the ambiguity resolution is required at all used frequencies.

ISSN:0149-0419    

DOI:10.1080/15210608809379575

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

J. S. Fein and P. L. Stephens (eds.),Monsoons(New York: John Wiley and Sons, 1987) 632 pp., $74.95 U.S.

ISSN:0149-0419    

DOI:10.1080/15210608809379576

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/15210608809379577

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/15210608809379570

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor