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Helicopter Magnetic Data

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Frequently-anticipated questions:


What does this data set describe?

Title: Helicopter Magnetic Data
Abstract:
These helicopter electromagnetic data were flown over a portion of Everglades National Park and surrounding areas in south Florida 9-14 December 1994. Two versions of the data are provided: the original dataset and the corrected dataset.
  1. How should this data set be cited?

    David Fitterman Maria Deszcz-Pan, 2002, Helicopter Magnetic Data: USGS Open-File Report 02-101, U.S. Geological Survey, Denver, CO.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -81.125
    East_Bounding_Coordinate: -80.375
    North_Bounding_Coordinate: 25.6
    South_Bounding_Coordinate: 25.125

  3. What does it look like?

    <https://sofia.usgs.gov/publications/ofr/02-101/diglocmapx.gif> (GIF)
    area covered by the Dighem helicopter electromagnetic survey

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

    Beginning_Date: 09-Dec-1994
    Ending_Date: 29941214
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: report

  6. How does the data set represent geographic features?

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

      Indirect_Spatial_Reference: Everglades National Park

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 17
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -81
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using Coordinate Pair
      Abscissae (x-coordinates) are specified to the nearest 0.1
      Ordinates (y-coordinates) are specified to the nearest 0.1
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    For a description of the channels in the original dataset see Table 3 (<https://sofia.usgs.gov/publications/ofr/02-101/table3.html>.

    For a description of the channels in the corrected dataset see Table 4 (<https://sofia.usgs.gov/publications/ofr/02-101/table4.html>)

    Entity_and_Attribute_Detail_Citation: USGS personnel


Who produced the data set?

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

    • David Fitterman

  2. Who also contributed to the data set?

    The U.S. Geological Survey contracted with Dighem, then a division of CGG Canada, Ltd, of Mississauga, Ontario, Canada, to fly a helicopter electromagnetic survey over parts of Everglades National Park and surrounding areas of south Florida.

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

    David Fitterman
    U.S. Geological Survey
    Project Chief
    P. O. Box 25046

    Denver Federal Center MS 964
    Denver, CO 80225
    USA

    303 236-1382 (voice)
    303 236-1425 (FAX)
    fitter@usgs.gov


Why was the data set created?

This project addressed the question of determining the location of the fresh-water/salt-water interface (FWSWI) in the coastal regions of southern Miami-Dade and Monroe counties, synoptic monitoring of changes in water quality associated with changes in water management practices, and looking for geophysical evidence of subsurface discharges to Florida Bay.

This project provided basic information needed to create ground-water models and test various restoration strategies and their impact on ground-water quality.


How was the data set created?

  1. From what previous works were the data drawn?

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

    Date: 1994 (process 1 of 2)
    During 9-14 December 1994 a helicopter electromagnetic survey was flown by Dighem, Mississauga, Ontario, Canada, over parts of Everglades National Park and surrounding areas in south Florida. The survey covered 398 square miles (1031 sq. Km) with flightlines totaling 1718 miles (2765 km). The data were collected towards the end of the wet season.

    Person who carried out this activity:

    David Fitterman
    U.S. Geological Survey
    Project Chief
    P. O. Box 25046

    Denver Federal Center MS 964
    Denver, CO 80225
    USA

    303 236-1382 (voice)
    303 236-1425 (FAX)
    fitter@usgs.gov

    Date: Unknown (process 2 of 2)
    Errors discovered in the original data due to problems with calibration and with the bird tow-cable length were corrected. See the section "Additional Corrections Applied to Original Data Set" in Fitterman David V. And Deszcz-Pan, Maria, 2002, Helicopter Electromagnetic Data from Everglades National park and Surrounding Areas, Florida: Collected 9-14, December, 1994, OFR 02-101 for more information on the correction procedures.

    Person who carried out this activity:

    Maria Deszcz-Pan
    U.S. Geological Survey
    Box 25046

    Denver Federal Center, MS 964
    Denver, CO 80225-0046
    USA

    303 236-1317 (voice)
    maryla@usgs.gov

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

    Fitterman, David V. Deszcz-Pan, Maria; Stoddard, 1999, Results of Time-Domain Electromagnetic Soundings in Everglades National Park, Florida: USGS Open-File Report 99-426, U.S. Geological Survey, Reston, VA.

    Online Links:

    Deszcz-Pan, M. Fitterman, D. V., Lason, V. F., 1998, Reduction of inversion errors in helicopter EM data using auxiliary information: Exploration Geophysics v. 29, Society of Exploration Geophysicists, Tulsa, OK.


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

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

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

    unknown

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

    During the interpretation of the datset provided by Dighem, errors in the data became apparent which caused difficulties in obtaining reliable layered-earth inversion models. These errors were traced to problems with calibration and with the bird tow-cable length. Calibration errors were corrected using a procedure described in Deszcz-Pan et al, 1998.


How can someone get a copy of the data set?

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

Access_Constraints: none
Use_Constraints: none

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

    Heather S.Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    helicopter electromagnetic data

  3. What legal disclaimers am I supposed to read?

    The data have no guarantees explicit or implied

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 25-May-2007
Metadata author:
Heather Henkel
U.S. Geological Survey
600 Fourth Street South
St. Petersburg, FL 33701
USA

727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
sofia-metadata@usgs.gov

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


This page is <https://sofia.usgs.gov/metadata/sflwww/helio_mag_data.faq.html>

U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Fri May 25 10:27:16 2007