Bathymetric data and grid of offshore Head of the Meadow Beach, Truro, MA on February 9, 2024

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Frequently anticipated questions:

What does this data set describe?

Title:
Bathymetric data and grid of offshore Head of the Meadow Beach, Truro, MA on February 9, 2024
Abstract:
The data in this release re-map the beach and nearshore environment at Head of the Meadow Beach in Truro, MA and provide updated environmental context for the 2020 CoastCam installation that looks out at the coast shared by beachgoers, shorebirds, seals, and sharks. This is a collaboration with the National Park Service at Cape Cod National Seashore to monitor the region that falls within the field of view of CoastCam CACO-01, which are two video cameras aimed at the beach. In February and March 2024, U.S. Geological Survey and Woods Hole Oceanographic Institution (WHOI) scientists conducted field surveys to collect topographic and bathymetric data. Images of the beach for use in structure-from-motion were taken with a camera (SONY a6000) 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 surface vehicle. Agisoft Metashape (v. 1.8.1) was used to create a digital surface model and orthomosaic with the collected imagery.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-011-FA.
  1. How might this data set be cited?
    Over, Jin-Si R., and Traykovski, Peter A., 20240530, Bathymetric data and grid of offshore Head of the Meadow Beach, Truro, MA on February 9, 2024: data release DOI:10.5066/P1N57AEG, 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, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., and Anderberg, Mira M., 2024, Topographic and bathymetric data, imagery, and ground control data collected at Head of the Meadow Beach, Truro, Massachusetts in February and March 2024: data release DOI:10.5066/P1N57AEG, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Over, J.R., Sherwood, C.R., Traykovski, P.A., and Anderberg, M.M., 2024, Topographic and bathymetric data, imagery, and ground control data collected at Head of the Meadow Beach, Truro, Massachusetts in February and March 2024: U.S. Geological Survey data release, https://doi.org/10.5066/P1N57AEG.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.07939297
    East_Bounding_Coordinate: -70.06812499
    North_Bounding_Coordinate: 42.05995004
    South_Bounding_Coordinate: 42.05012975
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/6616d181d34e7eb9eb7d6a50?name=2024-011-FA_HOM_bathymetry_browse.jpg&allowOpen=true (JPEG)
    Elevation relative to NAVD88-colored image of bathymetry
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 09-Feb-2024
    Currentness_Reference:
    ground condition; one day of data collection on February 9, 2024
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster and tabular 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?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00000001. Longitudes are given to the nearest 0.00000001. Latitude and longitude values are specified in Decimal degrees. 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 6378137.0.
      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: 0.0001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    2024-011-FA_HOM_bathymetry_UTM19N_NAVD88_1m.tif
    The GeoTIFF is the interpolated grid of the raw soundings representing the bathymetry of offshore Head of the Meadow Beach on February 9, 2024. (Source: USGS)
    Value
    Seafloor elevation orthometric height NAVD88 (m) using Geoid 18 in NAD83(2011)/UTM Zone 19N (Source: producer defined)
    ValueDefinition
    -999No data
    Range of values
    Minimum:-14.0331
    Maximum:1.5167
    Units:meters
    2024-011-FA_HOM_raw_bathymetry.csv
    The CSV file contains 36,759 data points of the processed unsmoothed s500 sonar data with interpolated PPK GNSS positions and the calculated seafloor_z from Processing Step 5. (Source: USGS)
    FAN
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2024-011-FAUSGS year, ID, and Field Activity
    Latitude NAD83[2011]
    Post-processed latitude of ASV GNSS antenna position of each data point. (Source: USGS)
    Range of values
    Minimum:42.05026368
    Maximum:42.05980501
    Units:decimal degrees
    Longitude NAD83[2011]
    Post-processed longitude of ASV GNSS antenna position of each data point. (Source: None)
    Range of values
    Minimum:-70.07918051
    Maximum:-70.06830738
    Units:decimal degrees
    Ellipsoid height NAD83[2011]
    Post-processed height in meters of ASV GNSS antenna position of each data point based on the NAD83(2011) reference ellipsoid. (Source: None)
    Range of values
    Minimum:-42.034
    Maximum:-25.185
    Units:meters
    Northing UTM19N
    Post-processed X-coordinate of ASV GNSS antenna position of each data point in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4655914.545
    Maximum:4656975.156
    Units:meters
    Easting UTM19N
    Post-processed Y-coordinate of ASV GNSS antenna position of each data point, in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:410699.883
    Maximum:411604.025
    Units:meters
    GPS_z
    Post-processed Z-coordinate of ASV GNSS antenna position of each data point using NAVD88 correction with Geoid 18. (Source: USGS)
    Range of values
    Minimum:0.212
    Maximum:4.777
    Units:meters
    Echo_z
    The unsmoothed Cerulean s500 bed detection range, or the distance between the echosounder and the bottom. (Source: USGS)
    ValueDefinition
    NaNNo data
    Range of values
    Minimum:-16.248
    Maximum:-0.923
    Units:meters
    Seafloor_z
    Elevation in meters of the seafloor in NAVD88, calculated using Seafloor_z = Echo_z + GPS_z - Antenna_Z_Offset. (Source: USGS)
    ValueDefinition
    NaNNo data
    Range of values
    Minimum:-14.464
    Maximum:2.400
    Units:meters
    Entity_and_Attribute_Overview:
    GeoTIFF raster has 920 columns and 1080 rows. Data from the GPS positions and echosounder data are the basis for the raster.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2024-011-FA

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Jin-Si R. Over
    • 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
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2297 (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 to observe conditions and change over time and to validate the CoastCam.

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-2024 (process 1 of 1)
    The single-beam bathymetry data were collected by launching the ASV Yellowfin into the water from the surf zone. Yellowfin is equipped with a Cerulean s500 echosounder and collects single-beam data and has an EMLID Reach M2 GPS for positioning data. The boat was controlled near the shore by Peter Traykovski and put on auto-pilot using predetermined tracklines for longer transects offshore. A base station was set-up on reference mark HOM RM1 for the duration of the survey. Note that on the day of collection the boat stopped multiple times due to being entangled with seaweed in the nearshore. The raw bathymetry data was processed with the following steps: 1.Parsed the echosounder data (NMEA GPS Puck, Time, and Echosounder range) into MATLAB (v. 2020b) using MATLAB Scripts developed by Peter Traykovski at WHOI - see contact below 2. Post Processed Kinematic (PPK) GNSS data from the ASV was corrected using the base station (Java Triumph-1) data in Emlid Studio (Version 1.4) using the datum NAD83(2011) and then Geoid 18 for the vertical datum NAVD88. A projection for UTM Zone 19N was also specified to get the Easting and Northing information. 3. Refined time alignment to account for any small time delays between GPS data and echosounder data collection. This is 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 36 seconds. The GPS measures vertical fluctuation of the boat due to waves and these fluctuations are also visible in echosounder data. Outliers in the echosounder data were removed using a de-spiking function. The equation in Step 5 removes the vertical fluctuation due to waves from the echosounder data leaving only true bathymetry if GPS and the echosounder are well synced. The lagged cross correlation processing ensures they are synced optimally. 4. The PPK GNSS elevation (GPS_z) positions (collected at a higher frequency than the echosounder) were interpolated to the time of echosounder samples (Echo_z) with the MATLAB function interp1 (linear interpolation). These interpolated data are available in 2024-011-FA_HOM_raw_bathymetry.csv 5. Calculated sea floor elevation with reference to the NAVD88 datum in meters using the following equation: Seafloor_z (Depth) = Echo_z + GPS_z - Antenna_Z_Offset; Antenna_Z_Offset = 0.1 m was the offset from the GNSS antenna to the echosounder transducer on the z-axis of the ASV. 6. 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. 7. 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 0.3 represented the surface in reference to NAVD88 in meters. 8. Exported gridded 1 m data in NAD83(2011)/UTM Zone 19N in NAVD88 meters as a GeoTIFF: 2024-011-FA_HOM_bathymetry_UTM19N_NAVD88_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
  3. What similar or related data should the user be aware of?
    Over, Jin-Si R., Sherwood, Chris R., and Traykovski, Peter A., 2023, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, MA in February and March 2023, U.S. Geological Survey Field Activity 2023-011-FA: data release DOI:10.5066/P9FYVLCD, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication is the survey data of Head of the Meadow Beach from 2023.
    Over, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., and Marsjanik, Eric, 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:

    Other_Citation_Details:
    This publication is the 2022 survey data of Head of the Meadow Beach.
    Over, Jin-Si R., Sherwood, Chris 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:

    Other_Citation_Details:
    This publication is the survey data of Head of the Meadow Beach from 2021.
    Over, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., Brosnahan, Sandra M., Marsjanik, Eric E., and Borden, John S., 2021, Topographic and bathymetric data, sediment samples, and beach imagery collected at Head of the Meadow, Truro in March 2020, U.S Geological Survey Field Activity 2020-015-FA: data release DOI:10.5066/P9KSG1RQ, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication is the survey data of Head of the Meadow Beach from 2020.
    Francis, Holly, and Traykovski, Peter A., 2021, Development of a highly portable unmanned surface vehicle for surf zone bathymetric surveying: Journal of Coastal Research Volume 37, Issue 5, Allen Press, online.

    Online Links:

    Other_Citation_Details:
    Volume 37, Issue 5, p. 933-945, this publication describes the theory behind attaching and processing data from a single beam echosounder attached to an autonomous survey vehicle.

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

  1. How well have the observations been checked?
    No official quality control (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 Over and others, 2021;2022;2023). The product is interpolated and small-scale bathymetry features are not resolved. The actual vertical values may be much less accurate between tracklines. Yaw, pitch, and roll, are not taken into account due to the wide beamwidth, for more processing information see Francis and Traykovski (2021).
  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 4.2 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 z SD of 5.5 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 cm. Individual point errors (20-30% of points) due to extreme movement of the ASV could be as high as 10 cm, but process steps to interpolate and fit the raster remove a large portion of varaibility.
  4. Where are the gaps in the data? What is missing?
    Collected 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 CSV of raw PPK and echosounder values have been edited to remove returns at the beginning and end of the survey when the Autonomous Surface Vehicle (ASV) was on land.
  5. How consistent are the relationships among the observations, including topology?
    The raster file represents single beam echo-sounder bathymetry data collected by Peter Traykovski (WHOI). These data are a combination of post-processed kinematic (PPK) elevations collected using a GNSS receiver (EMLID Reach M2) and soundings from a Cerulean s500 single beam echosounder mounted on a self-righting autonomous surface vehicle. PPK data were corrected to an onshore base station (JAVA Triumph). The GNSS antenna is offset from the echo-sounder by 0.1 m (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?

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. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  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? GeoTIFF 2024-011-FA_HOM_bathymetry_UTM19N_NAVD88_1m.tif is a grid of bathymetric data and then the raw GPS and echosounder data as a CSV file (2024-011-FA_HOM_raw_bathymetry.csv).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by 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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Not for navigational use.
  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.

Who wrote the metadata?

Dates:
Last modified: 30-May-2024
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)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P1N57AEG/2024-011-FA_HOM_bathymetry_meta.faq.html>
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