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1.
We evaluate the strengths and weaknesses of six publicly available global bathymetry grids: DBDB2 (Digital Bathymetric Data
Base; an ongoing project of the Naval Research Laboratory), ETOPO2 (Earth Topography; National Geophysical Data Center, 2001,
ETOPO2 Global 2’ Elevations [CD-ROM]. Boulder, Colorado, USA: U.S. Department of Commerce, National Oceanic and Atmospheric
Administration), GEBCO (General Bathymetric Charts of the Oceans; British Oceanographic Data Centre, 2003, Centenary Edition
of the GEBCO Digital Atlas [CD-ROM] Published on behalf of the Intergovernmental Oceanographic Commission and the International
Hydrographic Organization Liverpool, UK), GINA (Geographic Information Network of Alaska; Lindquist et al., 2004), Smith and
Sandwell (1997), and S2004 (Smith, unpublished). The Smith and Sandwell grid, derived from satellite altimetry and ship data
combined, provides high resolution mapping of the seafloor, even in remote regions. DBDB2, ETOPO2, GINA, and S2004 merge additional
datasets with the Smith and Sandwell grid; but moving from a pixel to grid registration attenuates short wavelengths (<20
km) in the ETOPO2 and DBDB2 solutions. Short wavelengths in the GINA grid are also attenuated, but the cause is not known.
ETOPO2 anomalies are offset to the northeast, due to a misregistration in both latitude and longitude. The GEBCO grid is interpolated
from 500 m contours that were digitized from paper charts at 1:10 million scale, so it is artificially smooth; yet new efforts
have captured additional information from shallow water contours on navigational charts. The S2004 grid merges the Smith and
Sandwell grid with GEBCO over shallow depths and polar regions, and so is intended to capture the best of both products. Our
evaluation makes the choice of which bathymetry grid to use a more informed one.
The U.S. government right to retain a non-exclusive royalty-free license in and to any copyright is acknowledged. 相似文献
2.
Carla J. Potter 《Geo-Marine Letters》1982,2(3-4):243-246
Large quantities of raw geotechnical data presently exist in the individual collections of institutions and agencies throughout
the world. In order to increase the usefulness of this vast amount of data to the scientific community, the National Geophysical
Data Center (NGDC) intends to develop a comprehensive data bank for geotechnical information to be located at NGDC, along
with a common format for the exchange of geotechnical information. This format would facilitate not only the transfer of geotechnical
information between researchers, but also simplify the exchange and development of computer software with which to manipulate
the data. 相似文献
3.
利用美国国家海洋大气管理局2007年发布的全球海域温、盐数据库资料,美国地球物理数据中心2006年发布的海底地形数据库资料以及日本海洋科学与技术机构2003年发布的1997—2002年东海地区月平均降水量资料,研究东海黑潮表层盐度的月季分布特征,并分析其影响因素。结果表明,东海黑潮表层盐度存在明显的月季变化特征。总体而言,12月至次年3月表层盐度高,6—9月表层盐度低,4、5月和10、11月为过渡阶段;表层盐度高值分布在东海黑潮主段靠近东边界一侧;6—9月入口段的表层盐度高于出口段的表层盐度,其他月份入口段的表层盐度低于出口段的表层盐度。东海黑潮表层盐度主要受表层温度、降水、径流的影响。冬、春、秋季的表层盐度分布在黑潮主段靠近陆架一侧区域受表层温度影响大;降水对东海黑潮表层盐度产生局部小范围的影响,时间主要集中在1月和6—8月份,区域分布在低纬25°N以南和30°N附近。长江冲淡水夏季对东海黑潮表层盐度的影响大于其他季节对东海黑潮表层盐度的影响,7月长江径流量达到最大值时,对应的黑潮扇形区的盐度最低。 相似文献
4.
Historically, measurement and collection of deep‐ocean acoustic imagery are accomplished by towed sidescan systems. Recently, work has been performed to extract acoustic imagery from current hull‐mounted wide‐swath bathymetric sonars with minimal hardware modification. Past work of deriving acoustic imagery from swath sonars has been performed primarily with SeaBeam's sixteen 22/3 ° preformed beams. The Navy is investigating the feasibility of extracting an acoustic image from the Sonar Array Survey Systems (SASS), a high‐resolution (1o beams) wide‐fan (90°) bathymetric system. Due to the large data volume (approximately 1 MB per ping), SASS normally discards the raw acoustic returns once bathymetry is calculated. In early 1991 the Naval Air Development Center (NADC) installed the hardware on board the USNS Maury to capture and record the raw acoustic signal (inphase and quadrature) from the SASS's 144 hydrophones for later inversion to a backscatter image. Preliminary qualitative mosaics of the sidescan images show promising results and warrant further development. 相似文献
5.
The Azores Archipelago is believed to be the site of the third arm of a Triple Junction between the Eurasia/Africa/North America plates. However, to the present no study has been able to identify its segmentation pattern, the spreading mechanism and its relationship with the well-known topographic features of the Mid-Atlantic Ridge (MAR). Here we present a new gravity compilation obtained with the existing National Geophysical Data Center (NGDC) data, merged with new gravity profiles collected during the ESCAPE cruise in 1995. This compilation is used to calculate a Free Air Anomaly (FAA) map, which is used to test two different models, the Mantle Bouguer Anomaly model and the elastic plate model, for the study of the thermal regime of the Terceira Axis. The analysis of the results from both models demonstrates that the elastic plate model successfully models the gravity data from the Azores Plateau and that there is no gravity evidence for the existence of a spreading axis. The elastic plate thickness Te, with a value of 7–8 km, suggests a very young lithosphere (about 10 Ma) at the time of the load of the Azores Plateau. 相似文献
6.
通过对当前国内外RTK三维定位技术在水深测量中的应用情况及相关资料的分析研究,从标准、规范的专用术语命名原则、通用性、科学性、完整性、前瞻性和涵盖面等方面,论证了"RTK三维水深测量"命名的正确性。 相似文献
7.
8.
John K. Hall 《Marine Geophysical Researches》2006,27(1):1-5
This special issue of Marine Geophysical Researches presents five papers dealing with GEBCO, the General Bathymetric Chart
of the Oceans, which celebrated its Centennial in April 2003, hosted by the International Hydrographic Bureau and the Principality
of Monaco. Over the past 103 years GEBCO has been the sole body dedicated to compiling all available data to produce standardized
maps of the oceans and seas covering 71% of planet Earth. Over time GEBCO has undergone a complete transformation as sparse
500 m contours on paper charts were replaced by digital grids with ever-increasing resolution. The 2003 Centennial saw the
release on two CDROMS with the first global 1′ grid, produced by methods unheard of in 1984, when GEBCO’s last 6th Edition
paper chart set was published. In GEBCO’s second century, the thrust is towards global grids that will capture the resolutions
available with evolving deep-water swath mapping technologies, as well as vast improvement in the details of the shallow continental
shelves that have traditionally been the preserve of the hydrographic community. As little more than 10% of the oceans have
been mapped to the desired level of detail, there is much to be done. However refinements in satellite altimetry appear to
offer an interim stop-gap as more multi-beam sonars ply the oceans and as the littoral countries of the world map their adjacent
marine areas for submission under Article 76 of UNCLOS (United Nations, 1983, 1999). In addition GEBCO is becoming increasingly proactive, with outreach to the public via the internet and a new GEBCO Map
of the World, active data-scrounging, and encouraging development of the first drifting buoys for acquiring data in the inaccessible
areas of the Antarctic, SW Pacific, and Arctic Oceans. 相似文献
9.
In 1979, the General Bathymetric Chart of the Oceans (GEBCO) published Sheet 5.17 in the Fifth Edition of its series of global
bathymetric maps. Sheet 5.17 covered the northern polar region above 64° N, and was for long the authoritative portrayal of
Arctic bathymetry. The GEBCO compilation team had access to an extremely sparse sounding database from the central Arctic
Ocean, due to the difficulty of mapping in this permanently ice covered region. In the past decade, there has been a substantial
increase in the database of central Arctic Ocean bathymetry, due to the declassification of sounding data collected by US
and British Navy nuclear submarines, and to the capability of modern icebreakers to measure ocean depths in heavy ice conditions.
From these data sets, evidence has mounted to indicate that many of the smaller (and some larger) bathymetric features of
Sheet 5.17 were poorly or wrongly defined. Within the framework of the project to construct the International Bathymetric
Chart of the Arctic Ocean (IBCAO), all available historic and modern data sets were compiled to create a digital bathymetric
model. In this paper, we compare both generally and in detail the contents of GEBCO Sheet 5.17 and version 1.0 of IBCAO, two
bathymetric portrayals that were created more than 20 years apart. The results should be helpful in the analysis and assessment
of previously published studies that were based on GEBCO Sheet 5.17.
Ron Macnab: Retired. 相似文献
10.
In this paper, we publish the results of a bathymetry survey based on the processing of satellite altimetry data. Data gathered from GEOSAT (Geodetic Mission), SEASAT, ERS-1 and TOPEX/POSEIDON satellites were processed to recover the seafloor topography over new seamounts in a test area located in the south central Pacific. We show that by processing high-density satellite altimetry data, alone or in combination with shiptrack bathymetric data, it is possible to produce full coverage bathymetric maps. 相似文献
11.
12.
Dziak Robert P. Fox Christopher G. Bobbitt Andra M. Goldfinger Chris 《Marine Geophysical Researches》2001,22(4):235-250
Full-coverage multibeam bathymetric maps of the southern section of the Juan de Fuca Plate, also known as the Gorda Plate,
are presented. The bathymetric maps represent the compilation of multibeam surveys conducted by the National Oceanic and Atmospheric
Administration during the last 20 yrs, and illustrate the complex tectonic, volcanic, and geomorphologic features as well
as the intense deformation occurring within this region. The bathymetric data have revealed several major, previously unmapped
midplate faults. A series of gently curving faults are apparent in the Gorda Plate, with numerous faults offsetting the Gorda
Plate seafloor. The multibeam surveys have also provided a detailed view of the intense deformation occurring within the Gorda
Plate. A preliminary deformation model estimated from basement structure is discussed, where the southern part of the plate
(south of ∼42°30′ N) seems to be deforming through a series of left-lateral strike-slip faults, while the northern section
appears to be moving passively with the rest of the Juan de Fuca Plate. The bathymetry also demonstrates the Mendocino and
Eel Canyons are prominent morphologic features in the northern California margin. These canyons are active depositional features
with a large sediment fan present at the mouths of both the Mendocino and Eel canyons. The depositional lobes of these fan(s)
are evident in the bathymetry, as are the turbidite channels that have deposited sediment along the fans over time. The Trinidad
Canyon is readily evident in the margin morphology as well, with a large (∼10 km) plunge pool formed at the mouth of the canyon
as it enters the Gorda Plate sediments.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
13.
HY-2 A(Haiyang-2 A), launched in 2011, is the first ocean dynamic environment satellite of China and is equipped with a radar altimeter as one of the primary payloads. HY-2 A shifted the drift orbit in March 2016 and has been accumulating geodetic mission(GM) data for more than three years with 168-day cycle. In this paper, we present the preliminary gravity field inverted by the HY-2 A/GM data from March 2016 to December 2017 near Taiwan(21°–26°N, 119°–123°E). The gravity anomaly is computed by Inverse Vening Meinesz(IVM) formula with a onedimensional FFT method during remove-restore procedure with the EGM2008 gravity model as the reference field. For comparison, CryoSat-2 altimeter data are used to inverse the gravity field near Taiwan Island by the same method. Comparing with the gravity field derived from CryoSat-2, a good agreement between the two data sets is found. The global ocean gravity models and National Geophysical Data Center(NGDC) shipboard gravity data also are used to assess the performance of HY-2 A/GM data. The evaluations show that HY-2 A and CryoSat-2 are at the same level in terms of gravity field recovery and the HY-2 A/GM altimeter-derived gravity field has an accuracy of 2.922 mGal. Therefore, we can believe that HY-2 A will be a new reliable data source for marine gravity field inversion and has the potentiality to improve the accuracy and resolution of the global marine gravity field. 相似文献
14.
15.
J. Carter Tate 《Marine Geodesy》2013,36(2-3):141-149
The Hydrographic Department and the Information Systems Department at the Naval Oceanographic Office (NAVOCEANO) successfully transmitted coastal area sounding and position data collected by USNS John McDonnell, a recently built survey vessel, from the Gulf of Mexico to NAVOCEANO at Stennis Space Center, Mississippi. Two external modems were used to modulate and demodulate the data that were received from a MICROVAX 3400 aboard USNS McDonnell and sent to the Intergraph Interactive Workstation at NAVOCEANO via the MARISTAT communication satellite. The Kermit file transfer protocol was used to bridge the different operating environments between input/output (I/O) devices and central processors. Office processors were able to evaluate the data prior to the departure of the survey platform from the area. From this data, smooth sheets‐were produced. Equipment upgrades and more efficient use of satellite availability within the entire INMARSAT system should allow near‐real‐time editing and validation of field hydro‐graphic data. 相似文献
16.
Abstract A new method is proposed with the aim of reducing dead reckoning error (DRE) during multibeam echosounding survey in deep ocean. Bathymetric data is used in this method to estimate DRE in position fixing. This method can be activated at any desired interval to check the DRE accumulation in addition to available external navigation systems. A pattern recognition algorithm is developed to quantify the shift in position of a selected bathymetric feature that has been observed already once. This difference is used to correct the position fixing and navigation data. 相似文献
17.
Christian J. Noll Timothy M. Dellapenna Andrea Gilkinson Randall W. Davis 《Geo-Marine Letters》2009,29(1):1-16
Surficial sediment distribution within Simpson Bay is a function of antecedent bedrock and recently deposited glacial geology,
as well as active physical processes both within Simpson Bay and Prince William Sound (PWS). Simpson Bay is a turbid, outwash
fjord located in northeastern PWS, Alaska. Freshwater from heavy precipitation, and the melting of high alpine glaciers enter
the bay through bay head rivers and small shoreline creeks. The catchment has a high watershed/basin surface area ratio (∼8:1),
and easily erodible bedrock that contribute to high sediment loads. The system can be divided into three discrete basins,
each with specific morphologic and circulatory characters. Side scan sonar, swath bathymetry, and seismic profiles reveal
that bathymetric highs are areas of outcropping glacial surfaces. High backscatter coupled with surface grab samples reveal
these surfaces to be composed of coarse sediment and bedrock outcrops. Bathymetric lows are areas of low backscatter, and
grab samples reveal these areas to be ponded deposits of organic-rich estuarine muds. The data provide evidence of terminal
morainal bank systems, and glacial grounding line deposits at the mouth of the bay and rocky outcrops were identified as subsurface
extensions of aerial rocky promontories. Radioisotope analyses of short cores reveal that the bay has an average accumulation
rate of approx. 0.5 cm year−1, but that this varies in function of the watershed/basin surface area ratios of the different basins. The interaction of
tidal currents and sediment source drives sediment distribution in Simpson Bay. Hydrographic data reveal high spatial variability
in surface and bottom currents throughout the bay. Subsurface currents are tide dominated, but generally weak (5–20 cm s−1), while faster currents are found along shorelines, outcrops, and bathymetric highs. Bathymetric data reveal steep slopes
with little to no modern sediment throughout the bay, suggesting lack of deposition due to tidal currents. 相似文献
18.
Naming of undersea features 总被引：2，自引：0，他引：2
Arnold H. Bouma 《Geo-Marine Letters》1990,10(3):119-125
The Intergovernmental Oceanographic Commission (IOC), the International Hydrographic Organization (IHO), and the joint IOC/IHO Guiding Committee for the General Bathymetric Chart of the Oceans (GEBCO) have expressed considerable concern about the indiscriminate and unregulated naming of undersea features which often go into print without any close scrutiny. An author may not realize that the feature has a name already, maybe in another language, or that his terminology conflicts with established definitions.Geo-Marine Letters wants to follow the IOC/IHO/GEBCO recommendations and requests that its authors follow the set forth guidelines. Examples of terms and definitions are given and addresses of national authorities provided. 相似文献
19.
B. Gjevik D. Hareide B. K. Lynge A. Ommundsen J. H. Skailand H. B. Urheim 《Marine Geodesy》2006,29(1):1-17
A system for displaying tidal currents in an electronic chart display and information system (ECDIS) has been developed and implemented in compliance with the standards of the International Hydrographic Organization (IHO). The tidal current fields can be displayed in real time on the electronic navigational chart and several options and functions for updating and zooming have been designed. The current fields are calculated from a data base with the harmonic constants for the four major tidal constituents. The harmonic constants are obtained from a high resolution numerical model with horizontal grid resolution of 100 m. The model is validated by comparing with sea level and current measurements. The depth matrix for the central part of the model domain was calculated from data from multibeam bathymetric surveys. An application example of the implementation is given for Trondheimsleia, a part of the main sailing route along the western coast of Norway. 相似文献
20.
Some errors and noises are often present in multibeam swath bathymetric data. Echo detection error (EDE) is one of the main errors. It causes the depth error to become bigger in outer beams and looks like sound refraction. But depth errors due to EDEs have a trumpet-shaped appearance, instead of a curved appearance that is caused by the sound refraction errors. EDEs, including systematic acoustic signal detection errors and internal noises, cannot be removed during the correction of sound refraction. It causes depth inconsistencies between adjacent swaths and degrades precision of outer beams. Sometimes, the bathymetric errors caused by EDEs do not even meet the requirements of IHO (International Hydrographic Organization). Therefore, a post-processing method is presented to minimize the EDEs by filtering outliers and compressing outer beams of multibeam bathymetric data. The outliers caused by internal noises are removed by an automatic filter algorithm first. Then the outer beams are compressed to reduce systematic acoustic signal detection errors according to their depths, the calculated depth line and standard deviations (SDs). The automatic filter process is important for calculating the depth line. The selection of inner beams to calculate the average SD of beam depths is crucial to achieving compressing goals. The quality of final bathymetric data in outer beams can be improved by these steps. The method is verified by a field test. 相似文献