The Davis Strait is a southern arm of the Arctic Ocean that lies north of the Labrador Sea . It lies between mid-western Greenland and Baffin Island in Nunavut , Canada. To the north is Baffin Bay . The strait was named for the English explorer John Davis (1550–1605), who explored the area while seeking a Northwest Passage . By the 1650s it was used for whale hunting .
64-1014: The International Hydrographic Organization defines the limits of the Davis Strait as follows: On the North. The Southern limit of Baffin Bay [The parallel of 70° North between Greenland and Baffin Land ]. On the East. The Southwest coast of Greenland. On the South. The parallel of 60° North between Greenland and Labrador . On the West. The Eastern limit of the Northwestern Passages South of 70° North [the East coast of Baffin Island to East Bluff, its Southeastern extremity] and of Hudson Strait [A line from East Bluff,
128-480: A computer-aided design (CAD) package, usually Autocad . Although the accuracy of crowd-sourced surveying can rarely reach the standards of traditional methods, the algorithms used rely on a high data density to produce final results that are more accurate than single measurements. A comparison of crowd-sourced surveys with multibeam surveys indicates an accuracy of crowd-sourced surveys of around plus or minus 0.1 to 0.2 meter (about 4 to 8 inches). NOAA maintains
192-497: A line to Cape Chidley , Labrador ( 60°24′N 64°26′W / 60.400°N 64.433°W / 60.400; -64.433 )]. The Davis Strait is underlain by complex geological features of buried grabens (basins) and ridges , formed by strike-slip faulting of the Ungava Fault Zone during Paleogene times about 45 million to 62 million years ago. The strike-slip faulting transferred plate-tectonic motions in
256-612: A permanent organization was formed and statutes for its operations were prepared. The IHB, now the IHO, began its activities in 1921 with 18 nations as members. The Principality of Monaco was selected as the seat of the Organization as a result of the offer of Albert I of Monaco to provide suitable accommodation for the Bureau in the Principality. The International Hydrographic Organization (IHO)
320-404: A single vertical grazing angle. The first MBES generation was dedicated to mapping the seafloor in deep water. Those pioneering MBES made little, or no, explicit use of the amplitudes, as their objective was to obtain accurate measurements of the bathymetry (representing both the peaks and deeps). Furthermore, their technical characteristics did not make it easy to observe spatial variations in
384-482: A thorough survey as a practical matter could include only a limited number of sounding measurements relative to the area being surveyed, inevitably leaving gaps in coverage between soundings. In 1904, wire-drag surveys were introduced into hydrography, and the United States Coast and Geodetic Survey ′s Nicholas H. Heck played a prominent role in developing and perfecting the technique between 1906 and 1916. In
448-403: A vessel to be gathered in a series of lines spaced at a specified distance. However, it shared the weakness of earlier methods by lacking depth information for areas in between the strips of sea bottom the vessel sounded. A multibeam echosounder (MBES) is a type of sonar that is used to map the seabed . It emits acoustic waves in a fan shape beneath its transceiver . The time it takes for
512-441: Is placed on soundings, shorelines, tides, currents, seabed and submerged obstructions that relate to the previously mentioned activities. The term hydrography is used synonymously to describe maritime cartography , which in the final stages of the hydrographic process uses the raw data collected through hydrographic survey into information usable by the end user . Hydrography is collected under rules which vary depending on
576-435: Is to be logged and rendered as a survey deliverable." in a set of contract survey requirements, is a clear indication that the wider hydrographic community is embracing the benefits that can be accrued by employing MBES technology and, in particular, are accepting as a fact that a MBES which provides acoustic backscatter data is a valuable tool of the trade. The introduction of multispectral multibeam echosounders continues
640-496: Is voluntarily joined with the goal of improving hydrography and safe navigation is conducted by the International Hydrographic Organization (IHO). The IHO publishes Standards and Specifications followed by its Member States as well as Memoranda of Understanding and Co-operative Agreements with hydrographic survey interests. The product of such hydrography is most often seen on nautical charts published by
704-719: The Hydrographic Dictionary and the Year Book are available to the general public free of charge from the IHO website. The IHO publishes the international standards related to charting and hydrography, including S-57, IHO Transfer Standard for Digital Hydrographic Data , the encoding standard that is used primarily for electronic navigational charts . In 2010, the IHO introduced a new, contemporary hydrographic geospatial standard for modelling marine data and information, known as S-100. S-100 and any dependent product specifications are underpinned by an on-line registry accessible via
SECTION 10
#1732876050945768-719: The United Nations , where it is the recognized competent authority on hydrographic surveying and nautical charting . When referring to hydrography and nautical charting in conventions and similar instruments, it is the IHO standards and specifications that are normally used. During the 19th century, many maritime nations established hydrographic offices to provide means for improving the navigation of naval and merchant vessels by providing nautical publications, nautical charts, and other navigational services. There were substantial differences in hydrographic procedures charts, and publications. In 1889, an International Maritime Conference
832-477: The Wayback Machine and ARGUS. Here, volunteer vessels record position, depth, and time data using their standard navigation instruments, and then the data is post-processed to account for speed of sound, tidal, and other corrections. With this approach there is no need for a specific survey vessel, or for professionally qualified surveyors to be on board, as the expertise is in the data processing that occurs once
896-433: The 1950s, 1960s and 1970s eventually made the wire-drag system obsolete. Sidescan sonar could create images of underwater obstructions with the same fidelity as aerial photography , while multibeam systems could generate depth data for 100 percent of the bottom in a surveyed area. These technologies allowed a single vessel to do what wire-drag surveying required two vessels to do, and wire-drag surveys finally came to an end in
960-883: The 20th century. So valuable was wire-drag surveying in the United States that for decades the U.S. Coast and Geodetic Survey, and later the National Oceanic and Atmospheric Administration, fielded a pair of sister ships of identical design specifically to work together on such surveys. USC&GS Marindin and USC&GS Ogden conducted wire-drag surveys together from 1919 to 1942, USC&GS Hilgard (ASV 82) and USC&GS Wainwright (ASV 83) took over from 1942 to 1967, and USC&GS Rude (ASV 90) (later NOAAS Rude (S 590) ) and USC&GS Heck (ASV 91) (later NOAAS Heck (S 591) ) worked together on wire-drag operations from 1967. The rise of new electronic technologies – sidescan sonar and multibeam swath systems – in
1024-514: The Convention on the IHO, the secretariat is headed by a Secretary-General, supported by two Directors. As before, all three senior members of the secretariat continue to be elected to their positions by the Member States at the regular Assembly of the IHO (formerly, IHO Conferences). The secretariat staff comprise a number of technical specialists, administrators, and support personnel. The bulk of
1088-525: The Davis Strait and Baffin Bay , but with several smaller concessions in the Greenland Sea in the east also. 65°N 58°W / 65°N 58°W / 65; -58 ( Davis Strait ) International Hydrographic Organization The International Hydrographic Organization ( IHO ) (French: Organisation Hydrographique Internationale ) is an intergovernmental organization representing hydrography . As of May 2024 ,
1152-412: The IHO comprised 100 member states. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters are properly surveyed and charted. It does this through the setting of international standards for hydrographic surveys, the co-ordination of the endeavors of the world's national hydrographic offices, and through its capacity building program. The IHO enjoys observer status at
1216-474: The IHO website. S-100 is aligned with the ISO 19100 series of geographic standards, thereby making it fully compatible with contemporary geospatial data standards. Because S-100 is based on ISO 19100, it can be used by other data providers for their maritime-related (non-hydrographic) data and information. Various data and information providers from both the government and private sector are now using S-100 as part of
1280-470: The IHO's technical and specialist expertise comes from Member States' personnel, often assisted by invited industry experts, who all provide technical contributions through participation in various IHO committees and working groups. A Council, comprising a sub-set of all the IHO Member States, meets annually and oversees the work of the IHO. A full description, together with details of the workings of all
1344-518: The Labrador Sea to Baffin Bay. It is the world's broadest strait. With a water depth of between one and two thousand meters the strait is substantially shallower than the Labrador Sea to the south. The strait is famous for its fierce tides that can range from 30 to 60 ft (9.1 to 18.3 m), which discouraged many earlier explorers. US Geological Survey has estimated that at least 13% of
SECTION 20
#17328760509451408-537: The National Ocean Survey (NOS) established a NOS study team to conduct investigations to determine the functional specifications for a replacement shallow water depth sounder. The outcome of the study was a class of vertical-beam depth sounders, which is still widely used. It simultaneously pinged at two acoustic frequencies, separated by more than 2 octaves, making depth and echo-amplitude measurements that were concurrent, both spatially and temporally, albeit at
1472-501: The Southeast extreme of Baffin Island ( 61°53′N 65°57′W / 61.883°N 65.950°W / 61.883; -65.950 ), to Point Meridian, the Western extreme of Lower Savage Islands , along the coast to its Southwestern extreme and thence a line across to the Western extreme of Resolution Island , through its Southwestern shore to Hatton Headland, its Southern point, thence
1536-679: The acceptance authority. Traditionally conducted by ships with a sounding line or echo sounding , surveys are increasingly conducted with the aid of aircraft and sophisticated electronic sensor systems in shallow waters. Offshore survey is a specific discipline of hydrographic survey primarily concerned with the description of the condition of the seabed and the condition of the subsea oilfield infrastructure that interacts with it. Hydrographic offices evolved from naval heritage and are usually found within national naval structures, for example Spain's Instituto Hidrográfico de la Marina . Coordination of those organizations and product standardization
1600-467: The acoustic backscatter angular response function to discriminate between different sediment types. Multispectral multibeam echosounders reinforces the fact that spatially and temporally coincident backscatter, from any given seabed, at widely separated acoustic frequencies provides separate and unique images of the seascape. Crowdsourcing also is entering hydrographic surveying, with projects such as OpenSeaMap , TeamSurv Archived 29 December 2020 at
1664-646: The aid of improved collection techniques and computer processing, the data is collected under one standard and extracted for specific use. After data is collected, it has to undergo post-processing. A massive amount of data is collected during the typical hydrographic survey, often several soundings per square foot . Depending on the final use intended for the data (for example, navigation charts , Digital Terrain Model , volume calculation for dredging , topography , or bathymetry ) this data must be thinned out. It must also be corrected for errors (i.e., bad soundings,) and for
1728-452: The continual echo returns from a receive beam that is perfectly aligned with the insonification beam using time-after-transmit, a technique that is independent of water depth and the cross-track beam opening angle of the sonar receive transducer. The initial attempt at multibeam imagery employed multiple receive beams, which only partially overlapped the MBES fan-shaped insonification beam, to segment
1792-481: The continual echo returns into intervals that were dependent on water depth and receiver cross-track beam opening angle. Consequently, the segmented intervals were non-uniform in both their length of time and time-after-transmit. The backscatter from each ping in each of the beam-parsed segments was reduced to a single value and assigned to the same geographical coordinates as those assigned to that beam's measured sounding. In subsequent modifications to MBES bottom imaging,
1856-459: The cross-track variation in echo amplitudes, to achieve high quality images of the seabed, it seemed a natural progression that the fan-shaped across-track pattern of insonification associated with the new monotone higher frequency shallow water MBES, might also be exploited for seabed imagery. Images acquired under the initial attempts at MBES bottom imaging were less than stellar, but fortunately improvements were forthcoming. Side scan sonar parses
1920-1113: The data is uploaded to the server after the voyage. Apart from obvious cost savings, this also gives a continuous survey of an area, but the drawbacks are time in recruiting observers and getting a high enough density and quality of data. Although sometimes accurate to 0.1 – 0.2m, this approach cannot substitute for a rigorous systematic survey, where this is required. Nevertheless, the results are often adequate for many requirements where high resolution, high accuracy surveys are not required, are unaffordable or simply have not been done yet. In suitable shallow-water areas lidar (light detection and ranging) may be used. Equipment can be installed on inflatable craft, such as Zodiacs , small craft, autonomous underwater vehicles (AUVs), unmanned underwater vehicles (UUVs), Remote Operated Vehicles (ROV) or large ships, and can include sidescan, single-beam and multibeam equipment. At one time different data collection methods and standards were used in collecting hydrographic data for maritime safety and for scientific or engineering bathymetric charts, but increasingly, with
1984-1002: The dredging, marine construction, oil exploration , and drilling industries. Industrial entities installing submarine communications cables or power require detailed surveys of cable routes prior to installation and increasingly use acoustic imagery equipment previously found only in military applications when conducting their surveys. Specialized companies exist that have both the equipment and expertise to contract with both commercial and governmental entities to perform such surveys . Companies, universities, and investment groups will often fund hydrographic surveys of public waterways prior to developing areas adjacent those waterways. Survey firms are also contracted to survey in support of design and engineering firms that are under contract for large public projects. Private surveys are also conducted before dredging operations and after these operations are completed. Companies with large private slips, docks, or other waterfront installations have their facilities and
Davis Strait - Misplaced Pages Continue
2048-528: The early 1990s. Vessels were freed from working together on wire-drag surveys, and in the U.S. National Oceanic and Atmospheric Administration (NOAA), for example, Rude and Heck operated independently in their later years. Single-beam echosounders and fathometers began to enter service in the 1930s which used sonar to measure the depth beneath a vessel. This greatly increased the speed of acquiring sounding data over that possible with lead lines and sounding poles by allowing information on depths beneath
2112-464: The early acoustic sounders were primarily based on the ability of magneostrictive and piezoelectric materials whose physical dimensions could be modified by means of electrical current or voltage. Eventually it became apparent, that while the operating frequency of the early single vertical beam acoustic sounders had little, or no, bearing on the measured depths when the bottom was hard (composed primarily of sand, pebbles, cobbles, boulders, or rock), there
2176-455: The echo amplitudes. Subsequent to the early MBES bathymetric surveys and at the time when single frequency side scan sonar had begun to produce high quality images of the seabed that were capable of providing a degree of discrimination between different types of sediments, the potential of the echo amplitudes from a MBES was recognized. With Marty Klein's introduction of dual frequency (nominally 100 kHz and 500 kHz) side scan sonar, it
2240-408: The echo sequence in each of the beam-parsed intervals was designated as a snippet. On each ping, each snippet from each beam was additionally parsed according to time-after-transmit. Each of the echo amplitude measurements made within a snippet from a particular beam was assigned a geographical position based on linear interpolation between positions assigned to the soundings measured, on that ping, in
2304-431: The effects of tides , heave , water level salinity and thermoclines (water temperature differences) as the velocity of sound varies with temperature and salinity and affects accuracy. Usually the surveyor has additional data collection equipment on site to measure and record the data required for correcting the soundings. The final output of charts can be created with a combination of specialty charting software or
2368-474: The field of standardization since the IHO was founded. The IHO has encouraged the formation of Regional Hydrographic Commissions (RHCs). Each RHC coordinates the national surveying and charting activities of countries within each region and acts as a forum to address other matters of common hydrographic interest. The 15 RHCs plus the IHO Hydrographic Commission on Antarctica effectively cover
2432-563: The implementation of the e-Navigation concept that has been endorsed by the UN International Maritime Organization (IMO). Another in the series of publications of interest is S-23, Limits of Oceans and Seas . The 3rd edition dates back to 1953 while the potential 4th edition, started in 1986, has remained a draft since 2002. It was distributed to IHO members, but its official publication has been suspended pending agreement between South Korea and Japan regarding
2496-529: The international standard name of the sea called " Japan Sea " in the 1953 edition. Hydrographic survey Hydrographic survey is the science of measurement and description of features which affect maritime navigation, marine construction, dredging , offshore wind farms, offshore oil exploration and drilling and related activities. Surveys may also be conducted to determine the route of subsea cables such as telecommunications cables, cables associated with wind farms, and HVDC power cables. Strong emphasis
2560-404: The most convenient form to enable them to be readily used; of instituting a prompt system of mutual exchange of hydrographic information between all countries; and of providing an opportunity to consultations and discussions to be carried out on hydrographic subjects generally by the hydrographic experts of the world." This is still the major purpose of the IHO. As a result of the 1919 Conference,
2624-673: The national agencies and required by the International Maritime Organization (IMO), the Safety of Life at Sea (SOLAS) and national regulations to be carried on vessels for safety purposes. Increasingly those charts are provided and used in electronic form unders IHO standards. Governmental entities below the national level conduct or contract for hydrographic surveys for waters within their jurisdictions with both internal and contract assets. Such surveys commonly are conducted by national organizations or under their supervision or
Davis Strait - Misplaced Pages Continue
2688-421: The obstruction was encountered. This method revolutionized hydrographic surveying, as it allowed a quicker, less laborious, and far more complete survey of an area than did the use of lead lines and sounding poles. From a navigational safety point of view, a wire-drag survey would not miss a hazard to navigation that projected above the drag wire depth. Prior to the advent of sidescan sonar , wire-drag surveying
2752-459: The open water near their facilities surveyed regularly, as do islands in areas subject to variable erosion such as in the Maldives. The history of hydrographic surveying dates almost as far back as that of sailing . For many centuries, a hydrographic survey required the use of lead lines – ropes or lines with depth markings attached to lead weights to make one end sink to the bottom when lowered over
2816-519: The organs of the IHO is available on the IHO website: www.iho.int The IHO develops hydrographic and nautical charting standards. These standards are subsequently adopted and used by its member countries and others in their surveys, nautical charts, and publications. The almost universal use of the IHO standards means that the products and services provided by the world's national hydrographic and oceanographic offices are consistent and recognizable by all seafarers and for other users. Much has been done in
2880-406: The output data set. Those positions are based on the backscatter measurements themselves and not by interpolation from some other derived data set. Consequently, multispectral multibeam imagery is more acute compared to previous multibeam imagery. The inherent precision of the bathymetric data from a multispectral multibeam echosounder is also a benefit to those users that may be attempting to employ
2944-581: The overlapping sets of side scanning across-track grazing angles at the two frequencies were always the same. Following the grounding of the Queen Elizabeth 2 off Cape Cod , Massachusetts , in 1992, the emphasis for shallow water surveying migrated toward full bottom coverage surveys by employing MBES with increasing operating frequencies to further improve the spatial resolution of the soundings. Given that side scan sonar, with its across-track fan-shaped swath of insonification, had successfully exploited
3008-402: The progressive advances in hydrography. In particular, multispectral multibeam echosounders not only provide "multiple look" depth measurements of a seabed, they also provide multispectral backscatter data that are spatially and temporally coincident with those depth measurements. A multispectral multibeam echosounder directly computes a position of origin for each of the backscatter amplitudes in
3072-513: The secretariat was renamed the "IHO Secretariat," which consists of an elected Secretary-General, two supporting Directors, and a small permanent staff (18 in 2020) at the Organization’s headquarters in Monaco. Until 2016 the IHO was administered by a secretariat headed by a Directing Committee comprising a President and two Directors. Since 8 November 2016, upon the entry in to force of revisions to
3136-410: The shallow (peak) soundings in the bottom data were retained in preference to deeper soundings in the sounding record. During that same time period, early side scan sonar was introduced into the operational practices of shallow water hydrographic surveying. The frequencies of the early side scan sonars were a matter of engineering design expediency and the most important aspect of the side scanning echoes
3200-470: The side of a ship or boat – and sounding poles, which were poles with depth markings which could be thrust over the side until they touched bottom. In either case, the depths measured had to be read manually and recorded, as did the position of each measurement with regard to mapped reference points as determined by three-point sextant fixes. The process was labor-intensive and time-consuming and, although each individual depth measurement could be accurate, even
3264-425: The sound waves to reflect off the seabed and return to the receiver is used to calculate the water depth. Unlike other sonars and echo sounders , MBES uses beamforming to extract directional information from the returning soundwaves, producing a swath of depth soundings from a single ping. Explicit inclusion of phraseology like: "For all MBES surveys for LINZ, high resolution, geo-referenced backscatter intensity
SECTION 50
#17328760509453328-545: The standards they have approved, particularly when the use is for the purposes of chart making and distribution or the dredging of state-controlled waters. In the United States, there is coordination with the National Hydrography Dataset in survey collection and publication. State environmental organizations publish hydrographic data relating to their mission. Commercial entities also conduct large-scale hydrographic and geophysical surveying, particularly in
3392-496: The trajectory of technological innovations providing the hydrographic surveying community with better tools for more rapidly acquiring better data for multiple uses. A multispectral multibeam echosounder is the culmination of many progressive advances in hydrography from the early days of acoustic soundings when the primary concern about the strength of returning echoes from the bottom was whether, or not, they would be sufficiently large to be noted (detected). The operating frequencies of
3456-437: The two adjacent cross-track beams. The snippet modification to MBES imagery significantly improved the quality of the imagery by increasing the number of echo amplitude measurements available to be rendered as a pixel in the image and also by having a more uniform spatial distribution of the pixels in the image which represented an actual measured echo amplitude. The introduction of multispectral multibeam echosounders continued
3520-400: The wire-drag method, a wire attached to two ships or boats and set at a certain depth by a system of weights and buoys was dragged between two points. If the wire encountered an obstruction, it would become taut and form a "V" shape. The location of the "V" revealed the position of submerged rocks, wrecks, and other obstructions, while the depth at which the wire was set showed the depth at which
3584-542: The world's undiscovered oil deposits and 30% of the world's undiscovered gas pockets are located in the Arctic, with the seas around Greenland potentially holding large amounts of natural gas and lesser amounts of crude oil and natural gas liquids . This has led Greenland's minister and provincial council to offer a large number of off-shore concessions to potential hydrocarbon (oil and gas) extraction. The largest concessions areas are located in seas west of Greenland, primarily
3648-754: The world. The IHO, in partnership with the Intergovernmental Oceanographic Commission, directs the General Bathymetric Chart of the Oceans program. Establishment of the Chart Specifications Committee and International Charts: Most IHO publications, including the standards, guidelines and associated documents such as the International Hydrographic Review , International Hydrographic Bulletin ,
3712-481: Was a noticeable frequency dependency of the measured depths when the bottom was soft (composed primarily of silt, mud or flocculent suspensions). It was observed that higher frequency single vertical beam echosounders could provide detectable echo amplitudes from high porosity sediments, even if those sediments appeared to be acoustically transparent at lower frequencies. In the late 1960s, single-beam hydrographic surveys were conducted using widely spaced track lines and
3776-403: Was apparent that spatially and temporally coincident backscatter from any given seabed at those two widely separated acoustic frequencies, would likely provide two separate and unique images of that seascape. Admittedly, the along-track insonification and receiving beam patterns were different, and due to the absence of bathymetric data, the precise backscatter grazing angles were unknown. However,
3840-538: Was established in June 1921 as the International Hydrographic Bureau (IHB). In 1970, the organization adopted its current name as part of a new International Convention on the IHO, which was agreed upon by its member nations. The term "International Hydrographic Bureau" continued to describe the IHO's secretariat until 8 November 2016, when a major revision to the Convention took effect. Following this change,
3904-620: Was held at Washington, D.C. , and it was proposed to establish a "permanent international commission." Similar proposals were made at the sessions of the International Congress of Navigation held at Saint Petersburg in 1908 and the International Maritime Conference held at Saint Petersburg in 1912. In 1919, the national Hydrographers of Great Britain and France cooperated in taking the necessary steps to convene an international conference of Hydrographers. London
SECTION 60
#17328760509453968-450: Was not the value of their amplitudes, but rather that the amplitudes were spatially variable. In fact, important information was deduced about the shape of the bottom and manmade items on the bottom, based on the regions where there were absences of detectable echo amplitudes (shadows) In 1979, in hopes of a technological solution to the problems of surveying in "floating mud", the Director of
4032-534: Was selected as the most suitable place for this conference, and on 24 July 1919, the First International Conference opened, attended by the Hydrographers of 24 nations. The object of the conference was "To consider the advisability of all maritime nations adopting similar methods in preparation, construction, and production of their charts and all hydrographic publications; of rendering the results in
4096-402: Was the only method for searching large areas for obstructions and lost vessels and aircraft. Between 1906 and 1916, Heck expanded the capability of wire-drag systems from a relatively limited area to sweeps covering channels 2 to 3 nautical miles (3.7 to 5.6 km; 2.3 to 3.5 mi) in width. The wire-drag technique was a major contribution to hydrographic surveying during much of the rest of
#944055