Airborne electromagnetic and magnetic survey, Goldstream Creek watershed, interior Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Airborne electromagnetic and magnetic survey, Goldstream Creek watershed, interior Alaska
Abstract:
A National Science Foundation grant to study Arctic hydrology-permafrost-methane systems was awarded to the University of Alaska Fairbanks (UAF), Institute of Northern Engineering, Water and Environmental Research Center with the Alaska Division of Geological & Geophysical Surveys (DGGS) as a co-investigator. As part of the study, DGGS managed the collection, modeling, and interpretation of airborne electromagnetic and magnetic data over a 258-square-km portion of the Goldstream Creek watershed, interior Alaska. The survey was flown from March 6th to March 17th, 2016 by CGG using their RESOLVE airborne geophysical system with a line spacing of either 100 meters (m) or 200 m; additional custom lines were collected over areas of scientific interest. The data were measured from 30 m above the ground surface using a helicopter-towed sensor platform ('bird') on a 30-m long line. Users can access the data, as well as additional metadata, from the DGGS website: <http://doi.org/10.14509/29681>.
Supplemental_Information:
ascii_data: ASCII format line data, other ASCII data 
>databases_geosoft: Geosoft format database of final line data, other Geosoft format databases >documents: Project and field reports, survey background information, gridded data explanations, other documentation >grids_ermapper: Geographically registered gridded data, ER Mapper ERS format >grids_geosoft: Geosoft-format binary grids, these grids can be viewed in ESRI ArcMap using a free plugin from Geosoft >images_registered: GeoTiff format images of all gridded data >kmz: kml language kmz archive files of several project data types including resistivity model depth slices >maps_pdf_format: Printable maps in pdf format >maps_prn_format: Printable maps in HPGL/2 printer file format with extension .prn >outreach_data: Data for the general public that requires no specialized software to view. Intended for educational use. Includes resistivity models >photos_flightpath: Survey flight path downward facing photos with GPS location in exif data >resistivity_models: ACSII CSV format resistivity models in project coordinates with data field guides, figures and supporting documentation in ASCII text, PDF, KML, and/or other form >vector_data: Line path, data contours, and survey boundary in ESRI shape file (SHP) format >video_flightpath: Survey flight path downward facing video
  1. How should this data set be cited?

    Emond, A.M., Daanen, R.P., Graham, G.R.C., Anthony, K.W., Liljedahl, A.K., Minsley, B.J., Barnes, D.L., Romanovsky, V.E., and Services, CGG Canada Ltd., 2018, Airborne electromagnetic and magnetic survey, Goldstream Creek watershed, interior Alaska: Geophysical Report GPR 2016-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 14 p

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -148.003945
    East_Bounding_Coordinate: -147.363899
    North_Bounding_Coordinate: 65.048766
    South_Bounding_Coordinate: 64.840942

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2016
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 6
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters

      The horizontal datum used is World Geodetic System of 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257223563000025.

  7. How does the data set describe geographic features?

    ascii_data
    ASCII format line data, other ASCII data (Source: CGG Canada Services Ltd.)

    databases_geosoft
    Geosoft format database of final line data, other Geosoft format databases (Source: CGG Canada Services Ltd.)

    documents
    Project and field reports, survey background information, gridded data explanations, other documentation (Source: CGG Canada Services Ltd.)

    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    grids_geosoft
    Geosoft-format binary grids, these grids can be viewed in ESRI ArcMap using a free plugin from Geosoft (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    images_registered
    GeoTiff format images of all gridded data (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    kmz
    kml language kmz archive files of several project data types including resistivity model depth slices (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    maps_pdf_format
    Printable maps in pdf format (Source: CGG Canada Services Ltd.)

    maps_prn_format
    Printable maps in HPGL/2 printer file format with extension .prn (Source: CGG Canada Services Ltd.)

    outreach_data
    Data for the general public that requires no specialized software to view. Intended for educational use. Includes resistivity models (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    photos_flightpath
    Survey flight path downward facing photos with GPS location in exif data (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    resistivity_models
    ACSII CSV format resistivity models in project coordinates with data field guides, figures and supporting documentation in ASCII text, PDF, KML, and/or other formats (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    vector_data
    Line path, data contours, and survey boundary in ESRI shape file (SHP) format (Source: Alaska Division of Geological & Geophysical Surveys (DGGS), Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)

    video_flightpath
    Survey flight path downward facing video (Source: CGG Canada Services Ltd.)


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    The Goldstream Valley Watershed project is funded by the National Science Foundation, Office of Polar Programs, Arctic System Science Program, award #1500931.

  3. To whom should users address questions about the data?

    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Rd
    Fairbanks, AK 99709-3707
    USA

    907-451-5020 (voice)
    dggsgis@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays


Why was the data set created?

The UAF and DGGS Goldstream Valley Watershed project aims to define processes within the hydrology-permafrost-methane system at the lake to watershed scale, and across seasonal to millennial time scales. Airborne-geophysical datasets were collected to facilitate understanding of surface and subsurface features and processes within Goldstream Valley and surrounding areas of interior Alaska. This sub-arctic region's hydrology-permafrost-methane system contains discontinuous permafrost and thaw lakes and offers a conveniently located and data-rich study area.


How was the data set created?

  1. From what previous works were the data drawn?

    Akima, H., 1970 (source 1 of 1)
    Akima, H., 1970, A new method of interpolation and smooth curve fitting based on local procedures: null v. 7, no. 4, Association for Computing Machinery, New York, NY, USA.

    Online Links:

    • null

    Type_of_Source_Media: paper
    Source_Contribution: Data collection, processing, and delivery

  2. How were the data generated, processed, and modified?

    Date: 2016 (process 1 of 4)
    Data collection, processing, and delivery - The supporting documents in digital data package "documents" provides detailed process steps.

    Data sources used in this process:

    • Akima, H., 1970

    Date: 2016 (process 2 of 4)
    Resistivity modeling - Resistivity models were derived from the recorded electromagnetic data through a process called inversion. Inversion programs create a resistivity model that has a data signature nearly the same as the recorded data. When this occurs the model is said to "fit" the data. This process is non-unique, meaning that many different resistivity models could create similar data. The readme file in digital data package "resistivity_models" provides inversion-specific information.

    Date: 2017 (process 3 of 4)
    Boundary polygon - The boundary polygon was generated by loading the final line data in Geosoft Oasis montaj v8.5.1. The final magnetic data was gridded using the Minimum Curvature option with the following settings: grid cell size = 1/5 of line spacing, blanking distance = double the line spacing, cells to extend beyond data = 0. The polygon file was created using Grid Outline tool with edge resolution = 1. The polygon file was exported to ESRI shapefile.

    Date: 2018 (process 4 of 4)
    Resistivity Depth Slices Grids, Images, and KMZ - Resistivity models were gridded at specific depths below surface using Geosoft Oaisis Montaj v9 to create Geosoft format grids. These depth slices were displayed with the same fixed color-scale by using a Geosoft *.zon file and exported to fixed color RGB GeoTiff images using Geosoft Oaisis Montaj v9. The resulting Geotiff images were imported into ArcMap v10. Using the "map to kml" tool in ArcMap v10 a keyhole markup language archive KMZ file was create making a GroundOverlay of each depth slice grid image. The KMZ was edited assigning a TimeSpan to each image where the 4 digit TimeSpan begin and end encompasses the depth below ground surface of the image. A resistivity colorbar was added to the KMZ as ScreenOverlay.

  3. What similar or related data should the user be aware of?

    Ball, L.B., Smith, B.D., Minsley, B.J., Abraham, J.D., Voss, C.I., Astley, B.N., Deszcz-Pan, Maria, and Cannia, J.C., 2014, Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010: Open-File Report OF 2011-1304, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 21 p
    Graham, G.C., Emond, A.M., Daanen, R.P., Minsley, B.J., and CGG, 2016, Airborne electromagnetic and magnetic survey, Yukon Crossing to Fox profile, interior Alaska: Geophysical Report GPR 2016-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Emond, A.M., Little, L.M., Graham, G.C., Minsley, B.J., and CGG, 2018, Airborne electromagnetic and magnetic survey, Yukon Crossing, interior Alaska: Geophysical Report GPR 2016-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Emond, A.M., Minsley, B.J., Daanen, R.P., Graham, G.C., and CGG, 2018, Airborne electromagnetic and magnetic survey, Western Yukon Flats, interior Alaska: Geophysical Report GPR 2016-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Geophysical data were acquired according to contractor, contract, and request-for-proposals specifications. For additional detail about survey parameters, see the accompanying project report available in the documents directory of this data distribution package.

  2. How accurate are the geographic locations?

    These data are positioned with post-processed differential GPS.

  3. How accurate are the heights or depths?

    These data are positioned with post-processed differential GPS.

  4. Where are the gaps in the data? What is missing?

    This data set includes files that contain processed aeromagnetic measurements, electromagnetic measurements, altimetry measurements, and locational data for the entire survey area.

  5. How consistent are the relationships among the observations, including topology?

    Data originate from one company using the same contract specifications for all data. The originating coordinate system was retained for all publication products.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.

  1. Who distributes the data set? (Distributor 1 of 1)

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    907-451-5020 (voice)
    907-451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (<http://www.dggs.alaska.gov>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    GPR 2016-5

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity, whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requestor or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 22-Aug-2018
Metadata author:
Simone Montayne
3354 College Road
Fairbanks, AK 99709-3707
USA

907-451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


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