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  • 1
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    ADCP current measurements (38 kHz) during RV METEOR cruise M176/2 (2022)
    PANGAEA
    Details
    Publication Date: 2024-01-26
    Description: Upper-ocean velocities along the cruise track of RV METEOR cruise M176/2 were continuously collected by a vessel-mounted Teledyne RD Instruments 38 kHz Ocean Surveyor ADCP. The transducer was located at 5.0 m below the water line. The instrument was operated in narrowband mode with 32 m bins and a blanking distance of 16.0 m, while 55 bins were recorded using a pulse of 2.90 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. Accuracy of the ADCP velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. Data post-processing included water track calibration of the misalignment angle (0.08° +/- 0.5936°) and scale factor (1.0026 +/- 0.0090) of the Ocean Surveyor signal. The average interval was set to 120 s.
    Keywords: Acoustic Doppler Current Profiler; ADCP; Current velocity, east-west; Current velocity, north-south; DAM_Underway; DAM Underway Research Data; DATE/TIME; DEPTH, water; Echo intensity, relative; GPF 21‐2_049, Rainbow Plume; LATITUDE; LONGITUDE; M176/2; M176/2_0_Underway-1; Meteor (1986); Pings, averaged to a double ensemble value; Quality flag, current velocity; Seadatanet flag: Data quality control procedures according to SeaDataNet (2010); South Atlantic Ocean; Vessel mounted Acoustic Doppler Current Profiler [38 kHz]; VMADCP-38
    Type: Dataset
    Format: text/tab-separated-values, 4359940 data points
    Location Call Number Expected Availability
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    DATA PANGAEA
  • 2
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    ADCP current measurements (38 kHz) during RV SONNE cruise SO289 (2022)
    PANGAEA
    Details
    Publication Date: 2024-01-26
    Description: Upper-ocean velocities along the cruise track of RV SONNE cruise SO289 were continuously collected by a vessel-mounted Teledyne RD Instruments 38 kHz Ocean Surveyor ADCP. The transducer was located at 6.0 m below the water line. The instrument was operated in narrowband mode with 32 m bins and a blanking distance of 16.0 m, while 50 bins were recorded using a pulse of 2.87 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. Accuracy of the ADCP velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. Data post-processing included water track calibration of the misalignment angle (-0.25° +/- 0.3777°) and scale factor (1.0004 +/- 0.0076) of the Ocean Surveyor signal. The average interval was set to 120 s.
    Keywords: Acoustic Doppler Current Profiler; ADCP; Calculated; Current velocity, east-west; Current velocity, north-south; DAM_Underway; DAM Underway Research Data; DATE/TIME; DEPTH, water; Echo intensity, relative; event was not logged in DSHIP; GEOTRACES GP21; LATITUDE; LONGITUDE; Pings, averaged to a double ensemble value; Quality flag, current velocity; SO289; SO289_0_Underway-1; SO289_0_Underway-4; Sonne_2; South Pacific Ocean; Vessel mounted Acoustic Doppler Current Profiler [38 kHz]; VMADCP-38
    Type: Dataset
    Format: text/tab-separated-values, 5473825 data points
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    DATA PANGAEA
  • 3
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    ADCP current measurements (75 kHz) during RV SONNE cruise SO289 (2022)
    PANGAEA
    Details
    Publication Date: 2024-01-26
    Description: Upper-ocean velocities along the cruise track of RV SONNE cruise SO289 were continuously collected by a vessel-mounted Teledyne RD Instruments 75 kHz Ocean Surveyor ADCP. The transducer was located at 6.0 m below the water line. The instrument was operated in narrowband mode with 8 m bins and a blanking distance of 8.0 m, while 100 bins were recorded using a pulse of 1.43 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. Accuracy of the ADCP velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. Data post-processing included water track calibration of the misalignment angle (-0.13° +/- 0.3581°) and scale factor (0.9969 +/- 0.0071) of the Ocean Surveyor signal. The average interval was set to 120 s.
    Keywords: Calculated; Current velocity, east-west; Current velocity, north-south; DAM_Underway; DAM Underway Research Data; DATE/TIME; DEPTH, water; Echo intensity, relative; GEOTRACES GP21; LATITUDE; LONGITUDE; Pings, averaged to a double ensemble value; Quality flag, current velocity; SO289; SO289_0_Underway-1; SO289_0_Underway-5; Sonne_2; Vessel mounted Acoustic Doppler Current Profiler [75 kHz]; VMADCP-75
    Type: Dataset
    Format: text/tab-separated-values, 11688975 data points
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    DATA PANGAEA
  • 4
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    Geophysical inversion for 3D contact surface geometry (2020)
    Society of Exploration Geophysicists
    Details
    Publication Date: 2020-10-21
    Description: Geologists’ interpretations about the earth typically involve distinct rock units with contacts between them. Three-dimensional geologic models typically comprise surfaces of tessellated polygons that represent the contacts. In contrast, geophysical inversions typically are performed on voxel meshes comprising space-filling elements. Standard minimum-structure voxel inversions recover smooth models, inconsistent with typical geologic interpretations. Various voxel inversion methods have been developed that attempt to produce models more consistent with such interpretations. However, many of those methods involve increased numerical challenges and ultimately the underlying parameterization of the earth is still inconsistent with geologists’ interpretations. Surface geometry inversion (SGI) is a fundamentally different approach that effectively takes some initial surface-based model and alters the position of the contact surfaces to better fit the geophysical data. Many authors have developed SGI methods. In contrast to those, we are the first to develop a method with the following characteristics: we work directly with 3D explicit surfaces from an input geologic model of arbitrary complexity; we incorporate intersection detection methods to avoid unacceptable topological scenarios; we use global optimization strategies and stochastic sampling to solve the inverse problem and aid model assessment; and we use surface subdivision to reduce the number of model parameters, which also provides regularization without adding the complication of trade-off parameters in the objective function. We test our methods on simpler synthetic examples taken from early influential literature, and we demonstrate their typical use on a more complicated example based on a seafloor massive sulfide deposit. Our work provides a geophysical inversion approach that can work directly with 3D surface-based geologic models. With this approach, geophysical and geologic models can share the same parameterization; there is only a single model, with no need to translate information between two inconsistent parameterizations.
    Print ISSN: 0016-8033
    Electronic ISSN: 1942-2156
    Topics: Geosciences , Physics
    Published by Society of Exploration Geophysicists
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    PAPER CURRENT
  • 5
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    Magnetic imaging of subseafloor hydrothermal fluid circulation pathways (2020)
    American Association for the Advancement of Science
    Details
    Publication Date: 2020-10-01
    Description: Hydrothermal fluid circulation beneath the seafloor is an important process for chemical and heat transfer between the solid Earth and overlying oceans. Discharge of hydrothermal fluids at the seafloor supports unique biological communities and can produce potentially valuable mineral deposits. Our understanding of the scale and geometry of subseafloor hydrothermal circulation has been limited to numerical simulations and their manifestations on the seafloor. Here, we use magnetic inverse modeling to generate the first three-dimensional empirical model of a hydrothermal convection system. High-temperature fluid-rock reactions associated with fluid circulation destroy magnetic minerals in the Earth’s crust, thus allowing magnetic models to trace the fluid’s pathways through the seafloor. We present an application of this modeling at a hydrothermally active region of the East Manus Basin.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science
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    PAPER CURRENT
  • 6
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    South Pacific GEOTRACES Cruise No. SO289, 18 February 2022 – 08 April 2022, Valparaiso (Chile) – Noumea (New Caledonia), GEOTRACES GP21 (2022)
    Gutachterpanel
    Details
    Publication Date: 2023-03-22
    Description: Research cruise SO289 with FS Sonne was sailed in austral autumn of 2022 in the South Pacific Ocean (SPO) from Valparaiso (Chile) to Noumea (New Caledonia), with a focus on trace element biogeochemistry and chemical oceanography but also including physical and biological oceanographic components. The research topic of the cruise was to determine in detail the distributions, sources and sinks of trace elements and their isotopes (TEIs) in the water column along a zonal section in one of the least studied ocean regions on earth. Our aim was to investigate the biogeochemical cycling of TEIs, and their interactions with surface ocean productivity and the carbon and nitrogen cycles (incl. N2 fixation) given that some TEIs act as micronutrients. The findings will have global significance for understanding the chemical environment in which ecosystems operate. The supply pathways of TEIs to the SPO from ocean boundaries including the atmosphere (Australian dust), continents (mainly Maipo River), sediments (on continental shelves/slopes), and ocean crust (hydrothermalism) were investigated. The TEI transport within water masses was determined with a focus on the southward flow of hydrothermally derived TEIs towards the Southern Ocean but also the deep inflow of Southern Ocean waters in the western SPO. The TEI transport assessment along the cruise track will allow a more reliable use of some TEIs as paleo-circulation proxies. The cruise will officially be part of the international GEOTRACES program.
    Type: Report , NonPeerReviewed
    Format: text
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    PAPER (OCEANREP)
  • 7
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    Magnetic and Gravity Surface Geometry Inverse Modelling of the TAG Active Mound (2021)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: Seafloor massive sulfide deposits form in remote environments, and the assessment of deposit size and composition through drilling is technically challenging and expensive. To aid the evaluation of the resource potential of seafloor massive sulfide deposits, three-dimensional inverse modelling of geophysical potential field data (magnetic and gravity) collected near the seafloor can be carried out to further enhance geologic models interpolated from sparse drilling. Here, we present inverse modelling results of magnetic and gravity data collected from the active mound at the Trans-Atlantic Geotraverse hydrothermal vent field, located at 26o08'N on the Mid-Atlantic Ridge, using autonomous underwater vehicle (AUV) and submersible surveying. Both minimum-structure and surface geometry inverse modelling methods were utilized. Through deposit-scale magnetic modelling, the outer extent of a chloritized alteration zone within the basalt host rock below the mound was resolved, providing an indication of the angle of the rising hydrothermal fluid and the depth and volume of seawater/hydrothermal mixing zone. The thickness of the massive sulfide mound was determined by modelling the gravity data, enabling the tonnage of the mound to be estimated at 2.17 +/- 0.44 Mt through this geophysics-based, non-invasive approach.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
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    PAPER (OCEANREP)
  • 8
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    Magnetic and gravity surface geometry inverse modeling of the TAG active mound (2021)
    American Geophysical Union
    Details
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(10),(2021): e2021JB022228, https://doi.org/10.1029/2021JB022228.
    Description: Seafloor massive sulfide deposits form in remote environments, and the assessment of deposit size and composition through drilling is technically challenging and expensive. To aid the evaluation of the resource potential of seafloor massive sulfide deposits, three-dimensional inverse modeling of geophysical potential field data (magnetic and gravity) collected near the seafloor can be carried out to further enhance geologic models interpolated from sparse drilling. Here, we present inverse modeling results of magnetic and gravity data collected from the active mound at the Trans-Atlantic Geotraverse hydrothermal vent field, located at 26°08′N on the Mid-Atlantic Ridge, using autonomous underwater vehicle and submersible surveying. Both minimum-structure and surface geometry inverse modeling methods were utilized. Through deposit-scale magnetic modeling, the outer extent of a chloritized alteration zone within the basalt host rock below the mound was resolved, providing an indication of the angle of the rising hydrothermal fluid and the depth and volume of seawater/hydrothermal mixing zone. The thickness of the massive sulfide mound was determined by modeling the gravity data, enabling the tonnage of the mound to be estimated at 2.17 ± 0.44 Mt through this geophysics-based, noninvasive approach.
    Description: The authors would like to thank the captain, crew, and scientific team from the 2016 R/V Meteor M127 and 1994 R/V Yokosuka MODE'94 cruises for all their work collecting the data modeled in this study. C. Galley is funded through an NSERC Discovery Grant and Memorial University's School of Graduate Studies Grant.
    Description: 2022-03-29
    Keywords: Seafloor massive sulfide deposit ; Potential field modeling ; Inverse modeling ; Gravity ; Magnetics
    Repository Name: Woods Hole Open Access Server
    Type: Article
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    PAPER (OA)
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