摘要:

Mapping and research on the seafloor adjacent to the United States has been a national effort involving elements of the Department of the Interior, the Department of Commerce, certain academic institutions, and private industry, the latter primarily for the exploration for oil and gas. These activities were accelerated by the USGS and NOAA in 1983, following the issuance of the EEZ (Exclusive Economic Zone) Proclamation by President Reagan. The intent of expanding the exploration already begun on the outer continental shelf (OCS) to the frontier of the EEZ is to determine the “characteristics”; and resource potential of this region. To coordinate this exploration, a Joint Office for Mapping and Research (JOMAR) has been established by the U.S. Geological Survey (in the Department of the Interior) and the National Oceanic and Atmospheric Administration (in the Department of Commerce). JOMAR's main purpose is to help direct and coordinate ongoing and planned seafloor related activities in the EEZ and prepare a 10‐year plan for mapping and research. JOMAR recently hosted a national symposium to identify the major elements of this plan. A comprehensive mapping and research plan will provide the needed direction and guide this national challenge.

ISSN:0149-0419    

DOI:10.1080/15210608809379586

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Studies of coastal bathymetry are important where littoral drift has implications on the planning of fishing and dredging operations. Also, there is a possibility of finding hitherto unknown bottom features in relatively less explored regions of the shallow seas around the globe. High resolution satellite imagery over oceans provides us with quantitative methods for estimating depth in shallow parts of the seas. One of the methods is the analysis of the refraction of coastal gravity waves observed on satellite imagery. A panchromatic image acquired by SPOT with 10 m resolution on March 22, 1986, over Bay of Bengal near Madras Coast, was used for this analysis. The image was enhanced to clearly bring out the wave structure seen on the sea surface. The image was then superimposed with a 1 km × 1 km grid. For each grid cell, 64 × 64 pixels at the center were considered for getting a Fast Fourier Transform to determine the wave spectrum and the dominant wavelength present there. The classical theory of gravity waves was used to relate the shallow water wavelengths obtained as above with the corresponding wavelengths in the deep water. The deep‐water wavelength was estimated to be 110 m using the known chart depths at a set of control points. The resulting depth estimates, when compared with standard bathymetric charts, were found, in general, to be well in agreement up to a depth of 30 m in the sea, with an r.m.s. error of 2.6 meters. The method seems to be very useful for remotely sensed bathymetric work. However, further research is required to reduce the error margin and operationalize the method.

ISSN:0149-0419    

DOI:10.1080/15210608809379587

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Bottom instrumentation is being used to collect diverse oceanographic, seismic, and geodetic data, often over prolong periods of time. Such data can be retrieved periodically using an acoustic communication link. Typical but conflicting requirements of such a link are high transmission rates, reliable transmission over long distances, and low power consumption of bottom transmitter. In this article a steerable narrow‐beam acoustic link is suggested as the best feasible approach offering improvement over broad‐beam systems. Various beam configurations are considered and compared in terms of their ability to reject ambient noise and multipath interference. A vertically suspended linear receiving array is postulated as the best solution to multipath suppression and beam tracking.

ISSN:0149-0419    

DOI:10.1080/15210608809379588

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A newly developed, compact long‐baseline (LBL) acoustic transponder system, used in several experiments for submarine and sea surface positioning, has proven to be easy to operate and reliable. Relocation of the ocean bottom transponders can be carried out to minimize vertical component errors of ship's positions. A transponder net is usually located via Loran‐C navigation in the western Pacific. Accuracy of positions acquired after relocation of the transponders is estimated to be a few meters at a slant range of several thousands of meters. Because several experiments have shown the difficulty of pinpointing the movement of an instrument towed from a ship, a transponder system is indispensable to precise underwater experiments.

ISSN:0149-0419    

DOI:10.1080/15210608809379589

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

L. Kubàycková, L. Kubček, and J. Kukuča,Probability and Statistics in Geodesy and Geophysics. (Elsevier Science Publishing Co., 1987), 427 pp.

ISSN:0149-0419    

DOI:10.1080/15210608809379590

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/15210608809379591

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/15210608809379592

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-0419    

DOI:10.1080/15210608809379585

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor