Shoreface Coastal Bathymetry Data Collected in June 2014 from Fire Island, New York: 50-Meter Digital Elevation Model

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Frequently anticipated questions:


What does this data set describe?

Title:
Shoreface Coastal Bathymetry Data Collected in June 2014 from Fire Island, New York: 50-Meter Digital Elevation Model
Abstract:
Scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center in St. Petersburg, Florida, collected bathymetric data along the upper shoreface and within the wilderness breach at Fire Island, New York, in June 2014. The U.S. Geological Survey is involved in a post-Hurricane Sandy effort to map and monitor the morphologic evolution of the shoreface along Fire Island and model the evolution of the wilderness breach as a part of the Hurricane Sandy Supplemental Project GS2-2B.During this study, bathymetry was collected with single-beam echo sounders and global positioning systems, mounted to personal watercraft, along the Fire Island shoreface and within the wilderness breach. Additional bathymetry was collected using backpack global positioning systems along the flood shoals and shallow channels within the wilderness breach.
  1. How might this data set be cited?
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center, 20160707, Shoreface Coastal Bathymetry Data Collected in June 2014 from Fire Island, New York: 50-Meter Digital Elevation Model: U.S. Geological Survey Data Series DS 1007, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

    This is part of the following larger work.

    Nelson, Timothy R., Miselis, Jennifer L., Hapke, Cheryl J., Wilson, Kathleen E., Henderson, Rachel E., Brenner, Owen T., Reynolds, Billy J., and Hansen, Mark E., 20160707, Coastal Bathymetry Data Collected in June 2014 from Fire Island, New York: the Wilderness Breach and Shoreface: U.S. Geological Survey Data Series DS 1007, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.228060
    East_Bounding_Coordinate: -72.866804
    North_Bounding_Coordinate: 40.733776
    South_Bounding_Coordinate: 40.605729
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Jun-2014
    Ending_Date: 20-Jun-2014
    Currentness_Reference:
    ground condition
  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 272 x 606 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: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum 1988
      Altitude_Resolution: 0.01 m
      Altitude_Distance_Units: meter
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?

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 St. Petersburg Coastal and Marine Science Center
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov

Why was the data set created?

To determine the change Hurricane Sandy caused in the shoreface morphology and breach evolution at Fire Island, New York, USA, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted a bathymetric survey of Fire Island from June 10-20, 2014. The objectives of the data collection effort were to map the morphology of the shoreface and the wilderness breach as part of the USGS Hurricane Sandy Supplemental Project GS2-2B. This dataset, 201406_Shoreface_DEM.zip, consists of a 50-m cell size, interpolated Digital Elevation Model (DEM) of the Fire Island shoreface.

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: 2014 (process 1 of 12)
    GPS Acquisition: GPS base stations were erected at benchmarks REST (near the town of Robins Rest) and U374 (NGS benchmark Permanent Identification number (PID#) KU0206) located on Fire Island. Base stations were equipped with Ashtech ProFlex 500 Global Navigation Satellite System (GNSS) receivers. The survey personal watercraft (PWC) (rovers) were equipped with ProFlex 500 GNSS receivers. The base and rover receivers recorded their positions concurrently at 10 Hertz (Hz) throughout the survey. Reference stations coordinates were verified with Continuously Operating Reference Station (CORS) sites using the Online Positioning User Service (OPUS), available at http://www.ngs.noaa.gov/OPUS/). U374 used reference stations ZNY1, NYRH, CTDA, while REST used stations NYCI, NYRH, and MOR6. OPUS computed both reference stations had horizontal errors of 0.4 cm and vertical errors of 0.2 cm. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Mark E. Hansen
    Oceanographer
    600 4th St. S
    Saint Petersburg, FL
    USA

    727-502-8036 (voice)
    727-502-8182 (FAX)
    mhansen@usgs.gov
    Date: 2014 (process 2 of 12)
    Single-Beam Sounding Acquisition: The single-beam bathymetric data were collected on two Yamaha (2010 and 2013) VX Deluxe personal watercraft. Each PWC was fitted with a single-beam transducer below the waterline off the starboard stern, 1.11 m beneath the GPS antenna position. HYPACK version 2013 was used for positioning and navigation during the survey. Depth soundings were recorded at 10 Hertz (Hz) using an Odom Ecotrac CV-100 Digital Hydrographic Echo Sounder system with 200 kHz transducers with 4-degree (10 June 2014) and 9-degree (remainder or survey) transducers. Soundings were merged into a raw data file (.raw) and a sounding file (.bin) in Hypack. Each file was named according to transect number and coordinated universal time (UTC). Water column sound velocity measurements were collected periodically throughout the survey, using a SonTek CastAway conductivity, temperature, and depth (CTD). Data were processed using SonTek CastAway CTD software version 1.5. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Billy J. Reynolds
    Engineering Technician
    600 4th St. South
    Saint Petersburg, FL
    USA

    727-502-8067 (voice)
    727-502-8181 (FAX)
    breynolds@usgs.gov
    Date: 2014 (process 3 of 12)
    Single-Beam Differentially Corrected Navigation Processing: Horizontal positions and vertical elevations associated with each single-beam sounding were post-processed using differential corrections derived from the base/rover setup. Two GPS reference stations were used for the survey and were located at benchmarks "U374" and "REST". Applying the reference station coordinates, GPS data acquired from the rover were processed to the concurrent GPS session data at the base station- using GrafNav version 8.5 software (Waypoint Product Group). The horizontal and vertical coordinates were recorded in the World Geodetic System of 1984 (WGS84) reference frame and exported as an ASCII file for each personal watercraft and each survey day. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Mark E. Hansen
    Oceanographer
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8036 (voice)
    727-502-8182 (FAX)
    mhansen@usgs.gov
    Date: 2014 (process 4 of 12)
    Single-Beam Data Processing: Single-beam soundings were merged with differentially processed GPS data and sound velocity profiles using Matlab R2014b. Each transect was visually inspected for elevation outliers and dropouts associated with wave breaking in the surf zone were manually corrected. Typically, the highest intensity return is generated by the seafloor surface. Breaking waves in the surf zone can create air bubbles in the water column and create an erroneous peak in waveform intensity, which causes errors in the interpreted seafloor reflection. When this situation was suspected, a corrected seafloor elevation was manually digitized by analyzing the complete waveform signal recorded by the Odom within the .bin data file. The soundings were corrected for the average speed of sound (table 1). A moving average filter was applied to the soundings to reduce instrument noise and the noise associated with the pitch and roll of the PWC. The depth soundings (from the transducer to the seafloor) were then adjusted to the depth from the GPS antenna and subsequently to the WGS84 ellipsoid. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2014 (process 5 of 12)
    Single-Beam Datum Transformation: NOAA's VDatum v3.3 was used to transform single-beam data points(x,y,z data) from their data acquisition datum (WGS84) to the North American Datum of 1983 (NAD83) reference frame and the North American Vertical Datum of 1988 (NAVD88) elevation using the National Geodetic Survey (NGS) geoid model of 2012A (GEOID12A). For conversion from the WGS84 ellipsoid to NAVD88 there is a total of 5.4 cm of uncertainty in the transformation (http://vdatum.noaa.gov/docs/est uncertainties.html). Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 6 of 12)
    Single-Beam Error Analysis: The accuracy of the single-beam soundings was evaluated by identifying locations where survey track lines crossed and soundings from each line were horizontally within 0.25 m of each other. Any track line with a root mean square (RMS) error of 12.2 cm for a total of 732 crossings. Since the mean error between wave runners was 0.5 cm, which is below the minimum resolution of the echosounder, no correction offset was applied to the individual echosounders. Applying the square root of the sum of the datum conversion uncertainty and the sounding uncertainty resulted in a combined vertical error of 13.3 cm. Horizontal uncertainty is assumed to be half of the vertical uncertainty (6.7 cm) at most. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    Saint Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 7 of 12)
    Merging Transects: Using Matlab R2015b, partial lines (the result of restarting the line in the middle of a transect) were subsequently merged with similar segments to create one seamless line. When repeats were present, only a single line was retained. The data were then combined into a single ASCII file consisting of position, elevation, line number, vessel number, and time of sampling. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 8 of 12)
    Extract Shoreface XYZ: Single-beam x,y,z data were imported into Esri’s ArcGIS version 10.2.2 using the “create feature class from xy table” tool, in ArcCatalog. Using ArcMap polygon was then created surrounding data points within the shoreface of Fire Island in ArcMap. The polygon vertices were converted to points using the “feature vertices to points” tool, “add xy coordinates” tool, and exported as an ASCII file using the “export feature attribute to ASCII” tool. This ASCII file was subsequently imported into Matlab R2015a. Any single-beam data within or on this polygon was then extracted and saved as an ASCII file. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 9 of 12)
    Create Digital Elevation Model: The shoreface single-beam x,y,z data were imported into ArcGIS using the "create feature class from xy table" tool in ArcCatalog. The dataset was then subsampled using the "subset features" and 10 percent of the data was removed to provide an estimate of the bathymetry uncertainty. The remaining 90 percent of the dataset was used to create a triangulated irregular network (TIN) using the "create TIN" tool. The TIN was subsequently converted into a raster file using the "TIN to Raster" tool with a cell size of 50 meters. The raster was exported as an ASCII file using the "ASCII to Raster" tool. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 10 of 12)
    Remove Extrapolated Cells: The Raster ASCII file was imported into Matlab 2015b and any interpolated grid cells that were more than two cell sizes (100 m) away from a shoreface data point were set to "Not a Number" (NaN). The raster data was then exported as an ArcGIS ASCII file from Matlab R2015b and imported into ArcMap using the "ASCII to Raster" tool. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 11 of 12)
    Evaluate Digital Elevation Model Uncertainty: The raster was sampled at the positions of the 10 percent removed data using the "extract values to points" tool and a .csv file was saved from each data table for the personal watercraft and backpack data. Using Matlab R2015b, the sampled data were compared to the subset data and the root mean square differences were calculated. The vertical RMS error was found to be 14 cm. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th St. South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Date: 2015 (process 12 of 12)
    Convert Raster Format: In ArcCatalog(TM), a raster dataset was created using the "create raster dataset" tool with a .tif image format, 64-bit pixel type. The shoreface raster was then imported into this dataset using the "mosaic" tool. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Timothy R. Nelson
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
    Data sources produced in this process:
    • 201406_Shoreface_DEM.tif
  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?
    The accuracy of the data is determined during data collection. This dataset is derived from a single field survey using identical equipment, set-ups, and staff; therefore, the dataset is internally consistent. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey mount. All the critical measurements are recorded manually and digitally entered into their respective programs. For single-beam soundings, the distance between the transducer and the GPS antenna was measured for each personal watercraft and accounted for during post-processing. For ground-based measurements, elevation between the ground and antenna was measured for each surveyor in a walking stride and accounted for during post-processing. For the base stations, the Ashtech ProFlex 500 system has a long static horizontal accuracy of 0.3 centimeters (cm) and 0.6 cm vertical accuracy. For the rovers, the post-processed kinematic horizontal instrument accuracy is 1 cm, and vertical accuracy is 2 cm. The Echotrac CV100 Digital Hydrographic Echo Sounder has a vertical accuracy of 0.01 m +/- 0.1% depth.
  2. How accurate are the geographic locations?
    The digital elevation model (DEM) uncertainty was determined by withholding 10% of the x,y,z bathymetric data points used to create the raster. The raster was then sampled at the withheld positions and a root mean square (RMS) error was calculated from the differences between sample and interpolated bathymetry. The horizontal uncertainty is assumed to be half the vertical uncertainty.
  3. How accurate are the heights or depths?
    The DEM uncertainty was determined by withholding 10% of the x,y,z bathymetric data points used to create the raster. The raster was then sampled at the withheld positions and a RMS error was calculated from the differences between sample and interpolated bathymetry.
  4. Where are the gaps in the data? What is missing?
    This zip archive contains a 50-m gridded digital elevation model (DEM) from June 2014 bathymetry data collected along the shoreface. Users are advised to read online Data Series and the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    The U.S. Geological Survey St. Petersburg Coastal and Marine Science Center collected shallow water bathymetric data of the shoreface and the wilderness breach on Fire Island, New York, in June 2014.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
The U.S. Geological Survey requests that it be referenced as the originator of this dataset in any future products or research derived from these data.
Use_Constraints: These data should not be used for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, St Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    Attn: Timothy R. Nelson
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8098 (voice)
    727-502-8182 (FAX)
    trnelson@usgs.gov
  2. What's the catalog number I need to order this data set? U.S. Geological Survey DS 1007
  3. What legal disclaimers am I supposed to read?
    This digital publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 05-Feb-2015
Last Reviewed: 29-Jan-2016
Metadata author:
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
Attn: Kathleen E. Wilson
Researcher
600 4th Street South
St. Petersburg, Florida
U.S.

727-502-8099 (voice)
727-502-8182 (FAX)
kwilson@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS1007_201406_Shoreface_DEM.faq.html>
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