Bathymetric data and grid of offshore Head of the Meadow Beach, Truro, on March 18, 2022

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Traykovski, Peter A., 20220919, Bathymetric data and grid of offshore Head of the Meadow Beach, Truro, on March 18, 2022: data release DOI:10.5066/P9GEVWG1, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

   Online Links:

   • https://doi.org/10.5066/P9GEVWG1
   • https://www.sciencebase.gov/catalog/item/62e009cfd34e952be9098186

   This is part of the following larger work.
   Over, Jin-Si R., Sherwood, Christopher R., and Traykovski, Peter A., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, MA in March 2022, U.S. Geological Survey Field Activity 2022-015-FA: data release DOI:10.5066/P9GEVWG1, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9GEVWG1
   • https://www.sciencebase.gov/catalog/item/62dee095d34e952be909417b

   Other_Citation_Details:

   Suggested Citation: 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 Beach, Truro, MA in March 2022, U.S. Geological Survey Field Activity 2022-015-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9GEVWG1.

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://www.sciencebase.gov/catalog/file/get/62e009cfd34e952be9098186?name=2022015FA_Truro_bathymetry_browse.JPG&allowOpen=true (JPEG)

   Elevation 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: 18-Mar-2022

   Currentness_Reference:

   ground condition; bathymetry was collected on a single day: March 18, 2022

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

   Geospatial_Data_Presentation_Form: raster and tabular 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: 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?

   2022015FA_Truro_Bathymetry_1m_cog.tif

   A 1-m cloud optimized GeoTIFF with encoded elevation values offshore at Head of the Meadow Beach, Truro, MA on March 18, 2022. Pixel row and column count are 874 and 787, respectively. (Source: producer defined)

   Value

   Surface elevation orthometric height NAVD88 (m) using Geoid 2012B in NAD83(2011) UTM Zone 19N (Source: producer defined)

   Value	Definition
   -999999	No data

   Range of values
   Minimum:	-12.439
   Maximum:	-0.099
   Units:	meters

   2022015FA_Truro_raw_bathymetry.csv

   A CSV file of the raw navigation GPS trackline data, echosounder returns, and seafloor elevation at Head of the Meadow Beach, Truro, MA on March 18, 2022. (Source: producer defined)

   INFO

   USGS Field Activity number (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)

   Value	Definition
   2022-015-FA	Year, ID, and Field Activity abbreviation

   Date

   Date at which values were taken in the format MM/DD/YYYY (Source: producer defined) Character string

   GPS_Time_UTC

   Time of GPS data in UTC, corrected with 18 sec delay in HH:MM:SS (Source: producer defined)

   Range of values
   Minimum:	14:52:38
   Maximum:	16:20:44
   Units:	meters

   Latitude_NAD83_2011

   Post-processed kinematic (PPK) latitude of GNSS antenna position relative to NAD83(2011). (Source: USGS)

   Range of values
   Minimum:	42.051347166
   Maximum:	42.059105169
   Units:	Decimal degrees

   Longitude_NAD83_2011

   Post-processed kinematic (PPK) longitude of GNSS antenna position relative to NAD83(2011). (Source: USGS)

   Range of values
   Minimum:	-70.079824915
   Maximum:	-70.070474236
   Units:	Decimal degrees

   Easting_UTM19N

   Post-processed kinematic (PPK) X-coordinates in NAD83(2011)/UTM Zone 19N. (Source: USGS)

   Range of values
   Minimum:	410646.024
   Maximum:	411424.882
   Units:	meters

   Northing_UTM19N

   Post-processed kinematic (PPK) Y-coordinates in NAD83(2011)/UTM Zone 19N. (Source: USGS)

   Range of values
   Minimum:	4656036.472
   Maximum:	4656897.928
   Units:	meters

   GPS_z

   Post-processed kinematic (PPK) position (Z-coordinates) of the GNSS receiver in reference to NAVD88 in meters on the autonomous survey vehicle. (Source: USGS)

   Range of values
   Minimum:	0.881
   Maximum:	2.151
   Units:	meters

   Echo_z

   The range to the seafloor from the echosounder in meters. (Source: USGS)

   Range of values
   Minimum:	-14.024
   Maximum:	-0.893
   Units:	meters

   Seafloor_z_NAVD88

   Elevation in meters of the seafloor in NAVD88, calculated by subtracting the Antenna_Z_offset (0.25 meters) from the GPS_z and adding the Echo_z. (Source: USGS)

   Range of values
   Minimum:	-12.855
   Maximum:	0.066
   Units:	meters

   Entity_and_Attribute_Overview:

   The GeoTIFF has 787 columns and 874 rows, and the 2022015FA_Truro_raw_bathymetry.csv has 26,433 records. The cloud-optimized GeoTIFF is in 32-bit floating point format representing elevation in meters relative to the NAVD88 datum. The CSV contains post-processed navigation GNSS data and the raw echosounder data as given in the Entity and Attribute Information section.

   Entity_and_Attribute_Detail_Citation: USGS Field Activity 2022-015-FA
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Peter A. Traykovski
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   Jin-Si R. Over

   U.S. Geological Survey, Woods Hole Coastal and Marine Science Center

   384 Woods Hole Rd

   Woods Hole, MA
   

   508-548-8700 x2297 (voice)

   jover@usgs.gov

Why was the data set created?

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: Mar-2022 (process 1 of 2)

   The single-beam bathymetry data were collected by launching the Autonomous Surface Vehicle (ASV) Yellowfin into the water from the surf zone. Yellowfin is equipped with a Cerulean s500 echosounder and collects position information with an EMLID Reach M2 GPS. 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 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 were corrected using base station (Java Triumph-1) data in Novatel Inertial Explorer (Version 8.70.8722) using the datum NAD83(2011) and 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 was corrected for in Step 5. 3. Refined time alignment to account for any small time delays between GPS data and echosounder data collection. This was accomplished using the time-lagged cross-correlation of echosounder range and PPK GNSS altitude in locations with a relatively flat bottom. The resulting time shift was 18 seconds. The GPS measured 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 leaves only true bathymetry if the GPS and echosounder were well-synced. The lagged cross-correlation processing ensured that they were synced optimally. 4. Duplicate times were removed from the PPK GNSS positions, and then the GPS values (GPS_z) were interpolated to the time of the Echosounder samples (Echo_z) with the MATLAB function interp1 (linear interpolation) and 'pchip'. 5. Calculated sea-floor elevation with reference to the NAVD88 datum in meters using the following equation: Seafloor_z = GPS_z - Antenna_Z_Offset + Echo_z; the offset from the GNSS antenna to the Echosounder transducer on the z-axis of the ASV was Antenna_Z_Offset = 0.25 m was. These xyz values of the GPS and Echosounder are provided in the CSV 2022015FA_Truro_raw_bathymetry.csv 7. Gridded Seafloor_z values 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 mask’s 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: 2022015FA_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: Jul-2022 (process 2 of 2)

   Bathymetry grid was turned into a cloud-optimized GeoTIFF (COG) using gdal_translate with the following command: for %i in (.\*.tif) do gdal_translate %i .\cog\%~ni_cog.tif -of COG -stats -co BLOCKSIZE=256 -co COMPRESS=DEFLATE -co PREDICTOR=YES -co NUM_THREADS=ALL_CPUS -co BIGTIFF=YES (v. 3.1.4 accessed October 20, 2020 https://gdal.org/), where i is the name of each GeoTIFF section. Person who carried out this activity:
   

   Jin-Si R. Over

   U.S Geological Survey, Woods Hole Coastal and Marine Science Center

   Geographer

   384 Woods Hole Rd

   Woods Hole, MA
   

   508-548-8700 x2297 (voice)

   jover@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, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9KSG1RQ

   Other_Citation_Details:

   This publication is the 2020 field data at Head of the Meadow Beach.

   Over, Jin-Si R., Sherwood, Christopher R., and Traykovski, Peter 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: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9D94NZ3

   Other_Citation_Details:

   This publication is the 2021 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?
   No official QC test was performed, but all depth values are internally consistent in relation to each other and are comparable to values of published bathymetry in the area (see cross-reference). The product is interpolated and small-scale bathymetry features are not resolved. The actual vertical position may be much less accurate between tracklines.
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 xy standard deviation (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 with a theoretical horizontal accuracy of 1-5 cm and average reported vertical SD of 1.1 cm. The navigational accuracies do not represent the accuracy of the derived bathymetric soundings. The vertical accuracy of the raw data in water depths of 10 meters or less, based on industry standard system specifications for 450 and 500 kHz transmit frequencies, is 5-10 centimeters.
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 of trackline and echosounder values has been edited to remove null returns at the beginning and end of the survey.
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 0.25 meters (referred to as Antenna_Z_Offset), and this is taken into account when calculating the depth in the trackline and echosounder variables (see Processing Steps).

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey - ScienceBase

   Denver Federal Center, Building 810, Mail Stop 302

   Denver, CO
   

   1-888- 275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? Cloud-optimized GeoTIFF 1m grid of bathymetric data (2022015FA_Truro_Bathymetry_1m_cog.tif) and CSV of raw GPS and echosounder data(2022015FA_Truro_raw_bathymetry.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?
   • Availability in digital form:

     Data format:	GeoTIFF (version 1.0.0) 32-bit floating point GeoTIFF format Size: 0.893
     Network links:	https://www.sciencebase.gov/catalog/file/get/62e009cfd34e952be9098186 https://www.sciencebase.gov/catalog/item/62e009cfd34e952be9098186 https://doi.org/10.5066/P9GEVWG1

     Data format:	The CSV files contains trackline and echosounder data. in format CSV (version Exported from Excel Office 365 16.01) Size: 2.07
     Network links:	https://www.sciencebase.gov/catalog/file/get/62e009cfd34e952be9098186 https://www.sciencebase.gov/catalog/item/62e009cfd34e952be9098186 https://doi.org/10.5066/P9GEVWG1

   • 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 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.

Who wrote the metadata?

Dates:

Last modified: 19-Sep-2022

Metadata author:

Jin-Si R. Over

U.S. Geological Survey, Woods Hole Coastal and Marine Science Center

Geographer

U.S. Geological Survey

Woods Hole, MA

508-548-8700 x2297 (voice)

whsc_data_contact@usgs.gov

Contact_Instructions:

The metadata contact email address is a generic address in the event the person is no longer with USGS.

Metadata standard:

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