25m Hillshaded Bathymetric ArcRaster Grid of Apalachicola Bay and St. George Sound, FL (APBAY25HS)

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Frequently anticipated questions:

What does this data set describe?

Title:
25m Hillshaded Bathymetric ArcRaster Grid of Apalachicola Bay and St. George Sound, FL (APBAY25HS)
Abstract:
These data were collected under a cooperative mapping program between the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration Coastal Services Center (NOAA\CSC), and the Apalachicola National Estuarine Research Reserve (NERR). The primary objectives of this program were to collect marine geophysical data to develop a suite of seafloor maps to better define the extent of oyster habitats, the overall seafloor geology of the bay and provide updated information for management of this resource. In addition to their value for management of the bay's oyster resources, the maps also provide a geologic framework for scientific research and the public High-resolution bathymetry, backscatter intensity, and seismic profile data were collected over 230 square kilometers of the floor of the bay. The study focused on the Apalachicola Bay and Western St. George Sound portions of the estuary mostly in depths > 2.0 meters.
Supplemental_Information:
These data are a 25m ArcRaster Grid of Apalachicola Bay and St. George Sound generated from swath sounding gridded at 5m. Refer to processing steps under data quality section for detailed methods.
  1. How might this data set be cited?
    U.S. Geological Survey, 2007, 25m Hillshaded Bathymetric ArcRaster Grid of Apalachicola Bay and St. George Sound, FL (APBAY25HS): Open-File Report 2006-1381, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Twichell, David C., Andrews, Brian D., Edmiston, H. Lee, and Stevenson, William R., 2007, Geophysical Mapping of oyster habitats in a shallow estuary; Apalachicola Bay, Florida: Open-File Report 2006-1381, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -85.096558
    East_Bounding_Coordinate: -84.753126
    North_Bounding_Coordinate: 29.789051
    South_Bounding_Coordinate: 29.597035
  3. What does it look like?
    http://pubs.usgs.gov/of/2006/1381/GIS/thumbnails/apbaybath25hs.jpg (JPEG)
    gray scale hillshaded image
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 14-Mar-2005
    Ending_Date: 27-Jun-2006
    Currentness_Reference:
    ground condition of two separate survey times: 20050314 to 20050413 and 20060529 to 20060627
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 828 x 1315 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 16
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -87.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 25.000000
      Ordinates (y-coordinates) are specified to the nearest 25.000000
      Planar coordinates are specified in meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    apbay25hs.vat
    Information unavailable from original metadata. (Source: Information unavailable from original metadata.)
    Rowid
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

Why was the data set created?

The purpose of this dataset is to produce a bathymetric hillshade grid from swath bathymetry that was collected within the survey boundary in St. George Sound and Apalachicola Bay.

How was the data set created?

  1. From what previous works were the data drawn?
    Information unavailable from original metadata. (source 1 of 1)
    U.S. Geological Survey, 2007, APBAYBATH25M - 25m Bathymetric Model of Apalachicola Bay and St. George Sound, Florida: Open-File Report 2006-1381, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Twichell, David C., Andrews, Brian D., Edmiston, H. Lee, and Stevenson, William R., 2007, Geophysical Mapping of oyster habitats in a shallow estuary; Apalachicola Bay, Florida.

    Online Links:

    Type_of_Source_Media: Information unavailable from original metadata.
    Source_Contribution: Information unavailable from original metadata.
  2. How were the data generated, processed, and modified?
    Date: Jan-2007 (process 1 of 5)
    Bathymetric hillshade was calculated with azimuth = 035, altitude = 045, vertical exaggeration = 5 Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x 2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Data sources used in this process:
    • apbaybth25m
    Data sources produced in this process:
    • apbay25hs
    Date: 28-Jun-2016 (process 2 of 5)
    Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The source information was incomplete and had to be modified to meet the standard. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 3 of 5)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 18-Nov-2019 (process 4 of 5)
    Crossref DOI link was added as the first link in the metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 5 of 5)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?

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?
    DGPS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. 99% of the positional data is DGPS. Unless noted, all GPS/DGPS data is referenced to WGS84 (NAD83). The configuration of the fathometer is as follows: The fathometer is mounted on a pole at the bow of the R/V RAFAEL. Offset between the fathometer pole and GPS antenna is measured. On ASV IRIS, the seismic profiler from which single-beam bathymetry measurements were collected was directly below the GPS antenna. No measurements were taken of ship's pitch, yaw, heave, or change in draft due to water and fuel usage. Motion of the fathometer is not measured. Horizontal accuracy of the fathometer is assumed to be within +/- 3 meters.
  3. How accurate are the heights or depths?
    Ship motion was recorded with a TSS DMS 2-05 Attitude Sensor, mounted on a head above the interferometric Submetrix 2000 Series transducers. Navigation was recorded using Real Time Kinematic Differential Global Positioning System (RTK-DGPS). The interferometric sonar is an angle-measuring system; depth accuracy decreases with increasing horizontal range. The combined angular accuracy of the Submetrix 2000 Series and the TSS DMS 2-05 attitude sensor is documented as 0.1 degrees. Assuming a constant angular accuracy, and using the International Hydrographic Standard (IHO) of a required 0.3 meter accuracy in < 30 meter water depth, all data collected within the survey fall within the IHO accuracy standards. However, vertical accuracy is also directly affected by the accuracy of both the navigation system and tidal measurements. RTK DGPS vertical accuracy is assumed to be 0.2 meters. Tidal elevations were derived from RTK -DGPS heights sent from a survey-specific base station located on St. George Island. The base station occupied a temporary monument. The x & y positions were calculated for that location using a 3 day average of 12 hour data sets using the Online Positioning User Service (OPUS, National Geodetic Survey) solution. Tidal elevations were calculated from NOAA Tidal Station #8728690 using the same OPUS solution and then applied to the corrected elevations for the base station at St. George Island. Antenna heights were referenced to Mean Lower Low Water (MLLW) for easier comparison of NOAA nautical charts
  4. Where are the gaps in the data? What is missing?
    Soundings were gridded in OMG SwathEd software using the entire swath width across track to achieve maximum coverage at the scale of the entire Apalachicola Bay/St. George Sound survey area. Although the soundings were manually edited, small data spikes may exist at outer edges of swath. Pockmark features that appear in the dredge channel of the intracoastal waterway fairways are artifacts of the of the processing methods used to generate a continuous surface from swath bathymetry collected on lines spaced 100m apart.
  5. How consistent are the relationships among the observations, including topology?
    These data have not been quantitatively compared to previous hydrographic data, although they generally agree with qualitative comparison of published NOAA charts.

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:
Data are not intended for navigational use. These data should not be used at resolutions for which it is not intended. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Hillshade grid representation of swath bathymetric data collected in the Apalachicola Bay and St. George Sound Florida in format AIG (version ArcGIS 9.2) ESRI Grid File Size: 0.454
      Network links: http://pubs.usgs.gov/of/2006/1381/GIS/raster/bath/apbay25hs.zip
      Media you can order: DVD-ROM (Density 4.75 Gbytes) (format UDF)
      Note: None
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    These data are available as an 8-bit continuous unsigned integer raster in Environmental Systems Research Institute (ESRI) format. To utilize these data, the user must have an image viewer, image processing or ESRI software capable of importing and ESRI ArcRaster grid.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
U.S. Geological Survey
Attn: Brian Andrews
Geographer
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2006-1381/apbay25hs-meta.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:20:22 2021