Bathymetric data during field activity 2021-014-FA offshore Head of the Meadow Beach, Truro MA on February 11, 2021

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Frequently anticipated questions:


What does this data set describe?

Title:
Bathymetric data during field activity 2021-014-FA offshore Head of the Meadow Beach, Truro MA on February 11, 2021
Abstract:
These data map the beach and nearshore environment at Head of the Meadow Beach in Truro, MA, providing updated regional context for the 2019 CoastCam installation. CoastCam CACO-01 are two video cameras aimed at the beach that view the coast shared by beachgoers, shorebirds, seals, and sharks. These data were collected as part of field activity 2021-014-FA and a collaboration with the National Park Service at Cape Cod National Seashore to monitor the region. In February 2021, U.S. Geological Survey and Woods Hole Oceanographic Institute (WHOI) scientists conducted field surveys to re-map the field of view of the CoastCam. Aerial images of the beach for use in structure from motion were taken with a camera (Ricoh GRII) and a post-processed kinematic (PPK) system attached to a helium powered balloon-kite (Helikite). High-precision GPS targets (AeroPoints) were used as ground control points. Bathymetry was collected in the nearshore using a single-beam echosounder mounted on a surf capable self-righting electric autonomous Small Surf Vehicle (SSV). Agisoft Metashape (v. 1.7.2) was used to create a digital elevation model with the collected imagery and this was merged with the bathymetry in MATLAB (v. 2020) to create a continuous topobathy product.
Supplemental_Information:
This bathymetric grid, as constructed using the raw echosounder and GPS data available in the 2021014FA_Bathyemtry.zip file, represents the nearshore of Head of the Meadow Beach in view of CoastCam CACO-01 cameras on February 11, 2021. The grid has sections of interpolation and has not been cloud optimized. For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-014-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 20220131, Bathymetric data during field activity 2021-014-FA offshore Head of the Meadow Beach, Truro MA on February 11, 2021: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Over, J., Sherwood, C., and Traykovski, P., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow, Truro in February 2021, U.S. Geological Survey Field Activity 2021-014-FA: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Over, J.R., Sherwood, C.R., and Traykovski, P.A., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow, Truro in February 2021, U.S. Geological Survey Field Activity 2021-014-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9D94NZ3
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.07988662
    East_Bounding_Coordinate: -70.07068035
    North_Bounding_Coordinate: 42.05852660
    South_Bounding_Coordinate: 42.05133652
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2021-014-FA/data/Topobathy/Bathymetry/2021014FA_Truro_bathymetry_browse.JPG (JPEG)
    Height relative to NAVD88-colored image of bathymetry data collected offshore of Head of the Meadow Beach, MA
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 11-Feb-2021
    Currentness_Reference:
    ground condition; bathymetry was collected on a single day: February 11, 2021
  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.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      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
      Ordinates (y-coordinates) are specified to the nearest 1
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      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 of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    2021014FA_Truro_bathymetry_1m.tif
    A 1-m raster dataset (GeoTIFF format) with encoded elevation values offshore at Head of the Meadow Beach, Truro, MA on February 11, 2021. Pixel row and column count are 952 and 721, respectively. (Source: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2012B in NAD83(2011) UTM Zone 19N (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    Range of values
    Minimum:-11.09
    Maximum:0.622
    Units:meters
    2021014FA_Truro_trackline_raw.csv
    A CSV file of the raw navigation GPS trackline data for the ASV at Head of the Meadow Beach, Truro, MA on February 11, 2021. (Source: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program)
    INFO
    USGS Field Activity number (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    ValueDefinition
    2021-014-FAYear, ID, and Field Activity abbreviation
    Date
    Time at which values were taken in the format dd-mmm-yyyy (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    Range of values
    Minimum:2021-02-11
    Maximum:2021-02-11
    GPS_Time_UTC
    Time of GPS data in UTC, corrected with 18 sec delay in HH:MM:SS (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    Range of values
    Minimum:14:59:18
    Maximum:16:31:37
    Units:meters
    Latitude
    Post-processed kinematic (PPK) latitude of GNSS antenna position relative to the NAD83(2011). (Source: USGS)
    Range of values
    Minimum:42.05138646
    Maximum:42.05847962
    Units:Decimal degrees
    Longitude
    Post-processed kinematic (PPK) longitude of GNSS antenna position relative to the NAD83(2011). (Source: USGS)
    Range of values
    Minimum:-70.07978519
    Maximum:-70.07078047
    Units:Decimal degrees
    H_Ell_m
    Post-processed kinematic (PPK) height in meters relative to the NAD83(2011) ellipsoid (Source: producer-defined)
    Range of values
    Minimum:-26.433
    Maximum:-23.53
    Units:meters
    Easting
    Post-processed kinematic (PPK) X-coordinates in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:410648.715
    Maximum:411398.961
    Units:meters
    Northing
    Post-processed kinematic (PPK) Y-coordinates in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4656041.051
    Maximum:4656828.271
    Units:meters
    ppk_Height_m
    Post-processed kinematic (PPK) height of GNSS antenna data in reference to NAVD88 in meters. (Source: USGS)
    Range of values
    Minimum:1.149
    Maximum:4.054
    Units:meters
    2021014FA_Truro_echo_raw.csv
    A CSV file of the raw dual frequency echosounder data for the ASV at Head of the Meadow Beach, Truro, MA on February 11, 2021. (Source: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program)
    INFO
    USGS Field Activity number (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    ValueDefinition
    2021-014-FAYear, ID, and Field Activity abbreviation
    Date
    Time at which values were taken in the format dd-mmm-yyyy (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    Range of values
    Minimum:2021-02-11
    Maximum:2021-02-11
    EchoTime_UTC
    Time of Echosounder data in UTC, in HH:MM:SS (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    Range of values
    Minimum:15:05:11
    Maximum:15:50:58
    depth200_m
    Depth value of echosounder 200kHz frequency in meters relative to NAVD88 in meters. (Source: producer-defined)
    ValueDefinition
    NaNNull value
    Range of values
    Minimum:-6.948
    Maximum:1.028
    Units:meters
    depth450_m
    Depth value of echosounder 450kHz frequency in meters relative to NAVD88 in meters. (Source: producer-defined)
    ValueDefinition
    NaNNull value
    Range of values
    Minimum:-11.528
    Maximum:1.372
    Units:meters
    Entity_and_Attribute_Overview:
    The GeoTIFF has 952 columns and 721 rows, the 2021014FA_Truro_trackline_raw.csv has 6,245 records, and the 2021014FA_Truro_echo_raw.csv has 13,734 records. The GeoTIFF is in 32-bit floating point format that represent elevation in meters relative to the NAVD88 datum. The trackline CSV contains post-processed navigation GNSS data and the echosounder CSV contains the raw echosounder data as given in the Entity and Attribute Information section.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-014-FA

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?
    Jin-Si Over
    U.S. Geological Survey
    U.S. Geological Survey 384 Woods Hole Rd
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov

Why was the data set created?

These data may be used as a high-resolution bathymetry dataset of Head of the Meadow Beach by the public, researchers, and others to observe ground conditions and change over time.

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: Feb-2021 (process 1 of 2)
    The bathymetry was collected by launching the SSV into the water from the surf zone. The boat was controlled near the shore by Peter Traykovski and put on auto-pilot using predetermined tracklines for longer transects offshore. The raw bathymetry data was processed with the following steps: 1. Parsed the binary data (BU353s4 GPS Puck, Time, Position and Echosounder range) into MATLAB (v. 2020b) from the EA24 Echosounder using MATLAB Scripts developed by Peter Traykovski at WHOI - see contact below 2. Post Processed Kinematic (PPK) GNSS (Novatel OEM-V2_L1L2) data from the vessel was corrected using the base station (Java Triumph-1) data in Novatel Inertial Explorer (Version 8.70.8722) using the datum NAD83(2011) and then GEOID 12B for the vertical datum NAVD88. A projection for UTM Zone 19N was also specified to get the Easting and Northing information. An antenna height of 0.0 was used and then the actual antenna height is corrected for in Step 5. 3. Refined time alignment to account for any small time delays between GPS data and Echosounder data collection by using time lagged cross correlation of Echosounder range and PPK GNSS altitude in locations with a relatively flat bottom (18 sec). The GPS measures vertical fluctuation of the boat due to waves and these fluctuations were also visible in echosounder data. The equation in Step 5 removed the vertical fluctuation due to waves from the echosounder data that leaves only true bathymetry if GPS and the Echosounder are well synced. The lagged cross correlation process ensures that they were synced optimally. 4. Duplicate times were removed from the PPK GNSS positions to create 2021014FA_Truro_trackline_raw.csv, then GPS values (ppk_Height) were interpolated to time of Echosounder samples (2021014FA_Truro_echo_raw.csv) with the MATLAB function interp1 (linear interpolation) and 'pchip'. 5. Calculated sea floor elevation (referred to as depth) with reference to the NAVD88 datum in meters using the following equation: Depth = ppk_Height - Antenna_Z_Offset + Echo 450kHz; Antenna_Z_Offset = 0.43 m was the offset from the GNSS antenna to the Echosounder transducer on the z-axis of the ASV. 7. Gridded 'Depth' onto 1 m resolution UTM eastings, northings using MATLAB file exchange script regularizedata3d by Jamal (2020), a cubic interpolation with the optimum smoothness coefficient determined by a Monte Carlo optimization procedure for the data regularization. Regularizedata3d entailed removing one cross-shore line of data from the processing and adjusting the smoothness parameter so the overall surface fit best fits the removed data. The process was then repeated for all the lines of data. The optimized smoothing parameter was used with all the data for the final processing. 8. The MATLAB function 'roipoly' returned the mask as a binary image, which sets pixels inside the region of interest (ROI) to 1 and pixels outside the ROI to 0. The boundary was developed so that there were no extrapolated bathymetry data outside the tracklines. The masks extent was the convex hull of the tracklines positions (x,y) and a bounding z coordinate of 0.8 represented the surface in reference to NAVD88 in meters. 9. Exported gridded 1 m data in NAD83(2011)/UTM Zone 19N in NAVD88 meters as a GeoTIFF: 2021014FA_Truro_bathymetry_1m.tif. Note that using NAVD88 as a height, means that the depths are not true-depths but the elevation of the seafloor above or below the geoid.
    Jamal (2020). RegularizeData3D (https://www.mathworks.com/matlabcentral/fileexchange/46223-regularizedata3d), MATLAB Central File Exchange. Retrieved September 23, 2020. Person who carried out this activity:
    Peter Traykovski
    Woods Hole Oceanographic Institution
    Associate Scientist
    226 Woods Hole Rd, MS #12
    Woods Hole, MA

    508-289-2638 (voice)
    ptraykovski@whoi.edu
    Date: 11-Apr-2022 (process 2 of 2)
    Update the publication date to 'go live' date. Modified browse graphic name to be the URL to the browse graphic. This work done on 20220307. Added PID to metadata (20220411). Any edits to the metadata also include an update to the metadata date. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Over, Jin-Si R., Sherwood, Christopher R., Traykovski, Peter A., Brosnahan, Sandra M., Martini, Marinna A., Marsjanik, Eric, and Borden, Jonathan S., 2021, Topographic and bathymetric data, sediment samples, and beach imagery collected at Head of the Meadow, Truro in March 2020: data release DOI:10.5066/P9KSG1RQ, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    This publication is the prior years field data at Head of the Meadow Beach.

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

  1. How well have the observations been checked?
    The GNSS receiver used on the autonomous survey vehicle (ASV) has theoretical vertical and horizontal accuracies of 5 centimeters.
  2. How accurate are the geographic locations?
    Navigation information was acquired from the GNSS receiver in PPK mode with a Multi-band GNSS antenna that has a theoretical horizontal accuracy of 1-5 cm and average reported SD of 1.0 cm.
  3. How accurate are the heights or depths?
    The location information was acquired from the GNSS receiver in PPK mode with a Multi-band GNSS antenna and hot shoe adapter with a theoretical horizontal accuracy of 1-5 cm and average reported SD of 1.6 cm.
  4. Where are the gaps in the data? What is missing?
    All collected survey line data were edited for erroneous soundings before being incorporated into the final bathymetric grid, the mask prevents extrapolation of data beyond the bounds but does not exclude any data. The raw CSV files of trackline and echosounder values have been edited to remove null returns at the beginning and end of the survey but still contain null values.
  5. How consistent are the relationships among the observations, including topology?
    This file represents single beam echo-sounder bathymetry data collected by Peter Traykovski (WHOI). These data were combined with post-processed kinematic (PPK) orthometric heights collected using a GNSS receiver (EMLID Reach M2) mounted on a self-righting ASV corrected to a base station (JAVA Triumph) onshore in GEOID12B NAVD88 meters. The GNSS antenna is offset from the echo-sounder by 0.43 meters (referred to as Antenna_Z_Offset), and this is taken into account when calculating the depth in the trackline variables(see Processing Steps).

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 Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Not for navigational use. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    Jin-Si Over
    U.S. Geological Survey
    Geographer
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov
  2. What's the catalog number I need to order this data set? Windows 10 zip folder 2021014FA_Truro_Bathymetry.zip containing a 32-bit floating point GeoTIFF 1m grid of bathymetric data (2021014FA_Truro_bathymetry_1m.tif), trackline positions (2021014FA_Truro_trackline_raw.csv), and echosounder values (2021014FA_Truro_echo_raw.csv).
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey 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?
  5. What hardware or software do I need in order to use the data set?
    These data are available as a 32-bit floating point GeoTIFF image. To utilize these data, the user must have an image viewer, image processing, GIS software package capable of importing a GeoTIFF image. Free spatial data viewers or proprietary software such as ArcGIS Earth or Google Earth Pro are capable of displaying the data. See: http://www.esri.com/software/arcgis-earth, or https://www.google.com/earth/desktop/.

Who wrote the metadata?

Dates:
Last modified: 11-Apr-2022
Metadata author:
Jin-Si Over
U.S. Geological Survey
Geographer
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2269 (voice)
jover@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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