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Mapping bathymetry: From measurement to applications
Stockholm University, Faculty of Science, Department of Geological Sciences.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Surface elevation is likely the most fundamental property of our planet. In contrast to land topography, bathymetry, its underwater equivalent, remains uncertain in many parts of the World ocean. Bathymetry is relevant for a wide range of research topics and for a variety of societal needs. Examples, where knowing the exact water depth or the morphology of the seafloor is vital include marine geology, physical oceanography, the propagation of tsunamis and documenting marine habitats. Decisions made at administrative level based on bathymetric data include safety of maritime navigation, spatial planning along the coast, environmental protection and the exploration of the marine resources.

This thesis covers different aspects of ocean mapping from the collection of echo sounding data to the application of Digital Bathymetric Models (DBMs) in Quaternary marine geology and physical oceanography. Methods related to DBM compilation are developed, namely a flexible handling and storage solution for heterogeneous sounding data and a method for the interpolation of such data onto a regular lattice. The use of bathymetric data is analyzed in detail for the Baltic Sea. With the wide range of applications found, the needs of the users are varying. However, most applications would benefit from better depth data than what is presently available. Based on glaciogenic landforms found in the Arctic Ocean seafloor morphology, a possible scenario for Quaternary Arctic Ocean glaciation is developed. Our findings suggest large ice shelves around parts of the Arctic Ocean during Marine Isotope Stage 6, 130–200 ka. Steered by bathymetry, deep water from the Amerasian Basin of the Arctic Ocean flows over the central Lomonosov Ridge into the Eurasian Basin. This water mass is traced on its continuing way towards Greenland and the Fram Strait. At the Morris Jesup Rise, bathymetry plays an important role in the partial re-circulation of the water into the Amerasian Basin.

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, Stockholm University , 2011. , 41 p.
Series
Meddelanden från Stockholms universitets institution för geologiska vetenskaper, 344
Keyword [en]
Ocean and coastal mapping, Digital Bathymetric Model, Geographical Information System, Applications of bathymetric data, Baltic Sea, Arctic Ocean, Seafloor morphology, Ocean circulation
National Category
Other Earth and Related Environmental Sciences
Research subject
Marine Geoscience
Identifiers
URN: urn:nbn:se:su:diva-57291ISBN: 978-91-7447-309-4OAI: oai:DiVA.org:su-57291DiVA: diva2:415311
Public defence
2011-06-08, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Submitted.

Available from: 2011-05-12 Created: 2011-05-05 Last updated: 2013-11-06Bibliographically approved
List of papers
1. A Data Model and Processing Environment for Ocean-Wide Bathymetric Data Compilations
Open this publication in new window or tab >>A Data Model and Processing Environment for Ocean-Wide Bathymetric Data Compilations
2008 (English)In: The international hydrographic review, ISSN 0020-6946, Vol. 9, no 1, 23-33 p.Article in journal (Refereed) Published
National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-14759 (URN)
Available from: 2008-12-10 Created: 2008-12-10 Last updated: 2011-05-06Bibliographically approved
2. Gridding heterogeneous bathymetric data sets with stacked continuous curvature splines in tension
Open this publication in new window or tab >>Gridding heterogeneous bathymetric data sets with stacked continuous curvature splines in tension
2011 (English)In: Marine Geophysical Researches, ISSN 0025-3235, E-ISSN 1573-0581, Vol. 32, no 4, 493-501 p.Article in journal (Refereed) Published
Abstract [en]

Gridding heterogeneous bathymetric data sets for the compilation of Digital bathymetric models (DBMs), poses specific problems when there are extreme variations in source data density. This requires gridding routines capable of subsampling high-resolution source data while preserving as much as possible of the small details, at the same time as interpolating in areas with sparse data without generating gridding artifacts. A frequently used gridding method generalizes bicubic spline interpolation and is known as continuous curvature splines in tension. This method is further enhanced in this article in order to specifically handle heterogeneous bathymetric source data. Our method constructs the final grid through stacking several surfaces of different resolutions, each generated using the splines in tension algorithm. With this approach, the gridding resolution is locally adjusted to the density of the source data set: Areas with high-resolution data are gridded at higher resolution than areas with sparse source data. In comparison with some of the most widely used gridding methods, our approach yields superior DBMs based on heterogeneous bathymetric data sets with regard to preserving small bathymetric details in the high-resolution source data, while minimizing interpolation artifacts in the sparsely data constrained regions. Common problems such as artifacts from ship tracklines are suppressed. Even if our stacked continuous curvature splines in tension gridding algorithm has been specifically designed to construct DBMs from heterogeneous bathymetric source data, it may be used to compile regular grids from other geoscientific measurements.

Place, publisher, year, edition, pages
Springer Netherlands, 2011
Keyword
Gridding, Ocean, Bathymetry
National Category
Geosciences, Multidisciplinary Geophysics
Research subject
Oceanography; Geology
Identifiers
urn:nbn:se:su:diva-67231 (URN)10.1007/s11001-011-9141-1 (DOI)000297371600005 ()
Available from: 2011-12-27 Created: 2011-12-26 Last updated: 2012-01-20Bibliographically approved
3. The use of bathymetric data in society and science: A review from the Baltic Sea
Open this publication in new window or tab >>The use of bathymetric data in society and science: A review from the Baltic Sea
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(English)Article in journal (Refereed) Submitted
Abstract [en]

Bathymetry, the underwater topography, is a fundamental property of oceans, seas and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data, which cannot be satisfied by the digital bathymetric models publicly available, despite of the abundance of high quality bathymetric data that are produced for safety of navigation purposes. Our study shows that DBMs based on such data could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.

Keyword
bathymetry, coastal environment, mapping, geospatial data, Baltic Sea
National Category
Other Earth and Related Environmental Sciences
Research subject
Marine Geoscience
Identifiers
urn:nbn:se:su:diva-57233 (URN)
Available from: 2011-05-05 Created: 2011-05-04 Last updated: 2013-11-06Bibliographically approved
4. High-resolution geophysical observations of the Yermak Plateau and northern Svalbard margin: Implications for ice-sheet grounding and deep-keeled icebergs
Open this publication in new window or tab >>High-resolution geophysical observations of the Yermak Plateau and northern Svalbard margin: Implications for ice-sheet grounding and deep-keeled icebergs
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2010 (English)In: Quaternary Science Reviews, ISSN 0277-3791, Vol. 29, no 25-26, 3518-3531 p.Article in journal (Refereed) Published
Abstract [en]

High-resolution geophysical evidence on the seafloor morphology and acoustic stratigraphy of the Yermak Plateau and northern Svalbard margin between 79°20′ and 81°30′N and 5° and 22°E is presented. Geophysical datasets are derived from swath bathymetry and sub-bottom acoustic profiling and are combined with existing cores to derive chronological control. Seafloor landforms, in the form of ice-produced lineations, iceberg ploughmarks of various dimensions (including features over 80 m deep and down to about 1000 m), and a moat indicating strong currents are found. The shallow stratigraphy of the Yermak Plateau shows three acoustic units: the first with well-developed stratification produced by hemipelagic sedimentation, often draped over a strong and undulating internal reflector; a second with an undulating upper surface and little acoustic penetration, indicative of the action of ice; a third unit of an acoustically transparent facies, resulting from debris flows. Core chronology suggests a MIS 6 age for the undulating seafloor above about 580 m. There are several possible explanations, including: (a) the flow of a major grounded ice sheet across the plateau crest from Svalbard (least likely given the consolidation state of the underlying sediments); (b) the more transient encroachment of relatively thin ice from Svalbard; or (c) the drift across the plateau of an ice-shelf remnant or megaberg from the Arctic Basin. The latter is our favoured explanation given the evidence currently at our disposal.

Keyword
Arctic Ocean, glacial morphology, ice sheets
National Category
Earth and Related Environmental Sciences
Research subject
Geology
Identifiers
urn:nbn:se:su:diva-47298 (URN)10.1016/j.quascirev.2010.06.002 (DOI)000284724400013 ()
Available from: 2010-12-07 Created: 2010-11-30 Last updated: 2011-11-21Bibliographically approved
5. An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data
Open this publication in new window or tab >>An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data
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2010 (English)In: Quaternary Science Reviews, ISSN 0277-3791, Vol. 29, no 25-26, 3505-3517 p.Article in journal (Refereed) Published
Abstract [en]

The hypothesis of floating ice shelves covering the Arctic Ocean during glacial periods was developed in the 1970s. In its most extreme form, this theory involved a 1000 m thick continuous ice shelf covering the Arctic Ocean during Quaternary glacial maxima including the Last Glacial Maximum (LGM). While recent observations clearly demonstrate deep ice grounding events in the central Arctic Ocean, the ice shelf hypothesis has been difficult to evaluate due to a lack of information from key areas with severe sea ice conditions. Here we present new data from previously inaccessible, unmapped areas that constrain the spatial extent and timing of marine ice sheets during past glacials. These data include multibeam swath bathymetry and subbottom profiles portraying glaciogenic features on the Chukchi Borderland, southern Lomonosov Ridge north of Greenland, Morris Jesup Rise, and Yermak Plateau. Sediment cores from the mapped areas provide age constraints on the glaciogenic features. Combining these new geophysical and geological data with earlier results suggests that an especially extensive marine ice sheet complex, including an ice shelf, existed in the Amerasian Arctic Ocean during Marine Isotope Stage (MIS) 6. From a conceptual oceanographic model we speculate that the cold halocline of the Polar Surface Water may have extended to deeper water depths during MIS 6 inhibiting the warm Atlantic water from reaching the Amerasian Arctic Ocean and, thus, creating favorable conditions for ice shelf development. The hypothesis of a continuous 1000 m thick ice shelf is rejected because our mapping results show that several areas in the central Arctic Ocean substantially shallower than 1000 m water depth are free from glacial influence on the seafloor.

Keyword
Arctic Ocean, Ice Shelves, Paleoceanography, Climate
National Category
Earth and Related Environmental Sciences
Research subject
Marine Geoscience
Identifiers
urn:nbn:se:su:diva-47302 (URN)10.1016/j.quascirev.2010.03.015 (DOI)000284724400012 ()
Available from: 2010-12-07 Created: 2010-11-30 Last updated: 2011-11-21Bibliographically approved
6. Flow of Canadian basin deep water in the Western Eurasian Basin of the Arctic Ocean
Open this publication in new window or tab >>Flow of Canadian basin deep water in the Western Eurasian Basin of the Arctic Ocean
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2010 (English)In: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, Vol. 57, no 4, 577-586 p.Article in journal (Refereed) Published
Abstract [en]

The LOMROG 2007 expedition targeted the previously unexplored southern part of the Lomonosov Ridge north of Greenland together with a section from the Morris Jesup Rise to Gakkel Ridge. The oceanographic data show that Canadian Basin Deep Water (CBDW) passes the Lomonosov Ridge in the area of the Intra Basin close to the North Pole and then continues along the ridge towards Greenland and further along its northernmost continental slope. The CBDW is clearly evident as a salinity maximum and oxygen minimum at a depth of about 2000 m. The cross-slope sections at the Amundsen Basin side of the Lomonosov Ridge and further south at the Morris Jesup Rise show a sharp frontal structure higher up in the water column between Makarov Basin water and Amundsen Basin water. The frontal structure continues upward into the Atlantic Water up to a depth of about 300 m. The observed water mass division at levels well above the ridge crest indicates a strong topographic steering of the flow and that different water masses tend to pass the ridge guided by ridge-crossing isobaths at local topographic heights and depressions. A rough scaling analysis shows that the extremely steep and sharply turning bathymetry of the Morris Jesup Rise may force the boundary current to separate and generate deep eddies.

Keyword
Deep water circulation; Intermediate water circulation; Arctic Ocean; Eurasian Basin
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-47295 (URN)10.1016/j.dsr.2010.01.006 (DOI)000276942400009 ()
Note
authorCount :17Available from: 2010-12-07 Created: 2010-11-30 Last updated: 2011-05-06Bibliographically approved

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