Single-Beam Bathymetry Sounding Data of Lemon Bay, Florida (2011) in XYZ format

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Frequently anticipated questions:


What does this data set describe?

Title:
Single-Beam Bathymetry Sounding Data of Lemon Bay, Florida (2011) in XYZ format
Abstract:
Lemon Bay is a long narrow body of water on the west central Florida coast, straddling both Sarasota and Charlotte counties. It encompasses nearly 7700 acres and ranges in depth from 7 meters (m) at Stump Pass to less than 10 centimeters (cm) on the many emergent shoals throughout the bay. The bay is home to a sizeable manatee population where they feed in the very shallow waters on sea grass. Manatees have been satellite tracked and found their daily routine includes moving to and from grass flats including crossing the Intercoastal Water Way (ICWW). Unfortunately, due to the configuration of the main ICWW, there is a high incident of manatee deaths due to boat collisions. In an effort reduce fatalities, the Florida Fish and Wildlife Conservation Commission (FWC) and the Wildlife Foundation of Florida (WFF) has developed a program entitled Manatee Response to Boats. 
This report serves as an archive of processed single-beam bathymetry data that were collected in Lemon Bay, Florida in 2011. Geographic information system data products include a XYZ data, bathymetric contours, and USGS quadrangle map. Additional files include formal Federal Geographic Data Committee (FGDC) metadata.
  1. How might this data set be cited?
    Hansen, Mark, 2015, Single-Beam Bathymetry Sounding Data of Lemon Bay, Florida (2011) in XYZ format: Archive of Bathymetry Data Collected in South Florida from 1995 to 2015 U.S. Geological Survey Data Series-1031, U.S. Geological Survey, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -82.43515
    East_Bounding_Coordinate: -82.26967
    North_Bounding_Coordinate: 27.04745
    South_Bounding_Coordinate: 26.82385
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2011
    Currentness_Reference:
    Data assumed to be constant over time but may change due to geologic processes.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (218513)
    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 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is WGS84-G1150.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: NAVD88
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    DS1031-LemonB_WGS84_NAVD88-G03_SB.xyz.txt, DS1031-LemonB_WGS84_NAVD88-G03_SB.xyz.shp
    Post-processed, area-specific x,y,z attributed single-beam bathymetry data. (Source: USGS)
    FID
    Field ID (Source: USGS)
    Range of values
    Minimum:0
    Maximum:218513
    longitude
    WGS84(G1150) x-coordinate (easting) of sample point (Source: NOAA/NGS UTMS)
    Range of values
    Minimum:-82.43515
    Maximum:-82.26967
    Units:decimal degrees
    Resolution:0.00000001
    latitude
    WGS84(G1150) y-coordinate (northing) of sample point (Source: NOAA/NGS UTMS)
    Range of values
    Minimum:26.82385
    Maximum:27.04745
    Units:decimal degrees
    Resolution:0.00000001
    z-ellipsoid height
    WGS84(G1150) ellipsoid height of sample point, in meters (Source: SANDS)
    Range of values
    Minimum:-30.061
    Maximum:-24.245
    Units:meters
    Resolution:0.001
    z-NAVD88
    Orthometric height of sample point, in meters. Relative to geoid model Geoid03. (Source: SANDS)
    Range of values
    Minimum:-6.294
    Maximum:-0.478
    Units:meters
    Resolution:0.001

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Mark Hansen
  2. Who also contributed to the data set?
    Florida Fish and Wildlife Conservation Commission (FWC) and The Wildlife Foundation of Florida (WFF) provided funding for the study. B.J Reynolds was the USGS principal investigator and Mark Hansen was the USGS co-investigator. Nancy DeWitt performed a significant portion of bathymetric survey data collection and processing.
  3. To whom should users address questions about the data?
    Mark Hansen
    U.S. Geological Survey
    Oceanographer
    600 Fourth Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    mhansen@usgs.gov

Why was the data set created?

The overarching goal of the study is to understand how manatees respond to water-craft in their natural environment in order to provide managers with a solid scientific basis for taking actions to reduce the risk of vessel strikes. The specific goal of this FWC funded project is to create a detailed bathymetric map of the 2007 study area in Lemon Bay using a vessel-mounted acoustic swath system. Data on bathymetry provide the essential physiographic context for understanding manatee-boat interactions and constraints on manatee movements and habitat use.

How was the data set created?

  1. From what previous works were the data drawn?
    USGS Lemon Bay bathymetry (source 1 of 1)
    U.S. Geological Survey, Unpublished material, 2011 Lemon Bay, Florida single-beam bathymetry.

    Type_of_Source_Media: digital tabular data
    Source_Contribution: Original processed single-beam bathymetric data.
  2. How were the data generated, processed, and modified?
    Date: 2011 (process 1 of 4)
    Data Acquisition - The sea-floor of Lemon Bay was mapped by using a jet ski, equipped with a high-precision Global Positioning Systems (GPS) coupled with a high-precision depth sounder. To accomplish this task, the SANDS (System for Accurate Nearshore Depth Surveying) system was developed by Mark Hansen (SPCMSC) and Jeff List (WHSC) of the U.S. Geological Survey. SANDS consists of two components, hardware and processing software.
    Survey track lines were spaced 100-meters apart and orientated in a north/south orientation. Channels and inlets were surveyed in greater detail. Track lines collected parallel to the bay shoreline (intersecting track lines) functioned to serve as a cross-check and to assess the relative vertical accuracy of the survey. Crossing lines are critical because they serve as a check on the internal accuracy of the data. Soundings were collected along each track line at 3 m spacing. In shallow areas, data were collected in a minimum of 0.3 m water depth except where there was potential damage to the bottom environment or the boat/motors.
    Reference GPS reference stations were operated on an USGS benchmark benchmark, typically located within approximately 15 km of the farthest single-beam track line. Reference and rover GPS receivers recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via ASHTECH choke-ring antennas. The reference and rover receivers record their positions concurrently at 1-second(s) recording intervals throughout the survey.
    Boat motion was recorded at 50-millisecond (ms) intervals using a TSS Dynamic Motion Sensor 05 (TSS DMS-05). Bathymetric soundings were recorded at 10-ms intervals using a Marimatech EC-100 survey grade echo-sounder. The single-beam data were acquired using the hydrographic software HYPACK version 5. All data strings from the instruments were streamed in real time and recorded through HYPACK software. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Mark Hansen
    Oceanographer
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    mhansen@usgs.gov
    Data sources produced in this process:
    • Raw sensor data files in ASCII text format and GPS Carrier-phase data in binary format.
    Date: 2011 (process 2 of 4)
    Differentially Corrected Navigation Processing- The coordinate values of the reference GPS base stations obtained from OPUS were provided in the ITRF00 coordinate system. All survey data for the project was referenced to WGS84. Consequently, reference station coordinates were transformed to WGS84 coordinates using the NOAA/NGS software HTDP v1.3. The respective reference (base) station coordinates utilized as reference positions were imported into PNAV v2.0 software by ASHTECH, Inc. Differentially corrected rover trajectories were computed by merging the master and rover the GPS data. During processing, steps were taken to ensure that the trajectories between the base and rover were clean, resulting in fixed positions. By analyzing the graphs, trajectory maps, and processing logs that GrafNav produces for each GPS session, GPS data from satellites flagged by the program as having poor health or satellite time segments that had cycle slips could be excluded, or the satellite elevation mask angle could be adjusted to improve the position solutions. The final differentially corrected precise DGPS positions were computed for each rover GPS session and exported in ASCII text format. Person who carried out this activity:
    Mark Hansen
    U.S. Geological Survey
    Oceanographer
    600 Fourth St. South
    St. Petersburg, FL

    727-502-8000 (voice)
    727-502-8032 (FAX)
    mhansen@usgs.gov
    Data sources produced in this process:
    • Boat trajectory data files in ASCII text format.
    Date: 2011 (process 3 of 4)
    Single-beam Bathymetry Processing- All data were processed using SANDS version 1.2. The primary purpose of SANDS is to time synchronize processed trajectories, soundings, and heave/pitch/roll, then merges all data strings. SANDS applies latency errors, applies geometric corrections for antenna staff pitch and roll, applies geometric corrections for antenna transducer pitch and roll (beam correction), time synchronizes the GPS trajectory and HYPACK files for each GPS epoch, and converts WGS84 latitude/longitude coordinates to North American Datum of 1983 NAD83/GRS80 UTM coordinates (m), and applies a geoid separation based upon the NOAA/NGS Geoid03 model. Latitude/longitude conversion to UTM coordinates was accomplished using NOAA/NGS UTM v2.0 software. Intermediate output files are comma delimited text files containing: time of day (seconds of day), UTM X coordinate (m), UTM Y coordinate (m), ellipsoid height, orthometric height, smoothed raw depths, Grafnav RMS value, and HYPACK line number. A header line indicates the attributes entry for each column. Person who carried out this activity:
    Mark Hansen
    U.S. Geological Survey (USGS) - St. Petersburg Coastal and Marine Science Center
    Oceanographer
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    727-502-8032 (FAX)
    mhansen@usgs.gov
    Data sources used in this process:
    • Completely processed final XYZ files representing sea-floor elevations.
    Data sources produced in this process:
    • Final processed bathymetry data files in ASCII text format.
    Date: 2015 (process 4 of 4)
    The final processed bathymetry files were reformatted for publication. UTM coordinate were converted to latitude/longitude using NOAA/NGS UTMS v2.0 software. Shapefiles were created from X,Y,Z text files using in-house developed software. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Mark Hansen
    Oceanographer
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    (727) 502-8032 (FAX)
    mhansen@usgs.gov
    Data sources produced in this process:
    • DS1031-LemonB_WGS84_NAVD88-G03_SB.xyz.txt, DS1031-LemonB_WGS84_NAVD88-G03_SB.xyz.shp
  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 multiple research cruises using identical equipment, set-ups, and staff; therefore, it is internally consistent. Methods are employed to maintain data collection consistency aboard the platform. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey platform. All the critical measurements are recorded manually and digitally entered into their respective programs. Offsets between the single-beam transducers and the Ashtech antenna reference point (ARP) were measured and accounted for in post-processing. Bar checks were performed as calibration efforts and accounted for any drift in the Marimatech Echosounder. Differential Geographic Positioning System (DGPS) coordinates were obtained using post-processing software packages developed by the National Oceanic and Atmospheric Administration (NOAA)/National Geodetic Survey (NGS) Online Positioning User Service (OPUS). Boat trajectories were computed with Grafnav v8.1 software by Novatel, Inc. These bathymetric data have not been independently verified for accuracy.
  2. How accurate are the geographic locations?
    The GPS antenna and receiver acquisition configuration used at the reference station was duplicated on the survey vessel (rover). The base receiver and the rover receiver record their positions concurrently at 1Hz recording intervals throughout the survey. All processed measurements are referenced to the base station coordinates.
    GPS base or differential reference stations were operated within approximately 15 to 20 km of the survey area. Two new temporary ground-control points or benchmarks (surveyed to within 1 cm to 2 cm accuracy) were established throughout the study area for use as reference receiver sites using standard benchmarks procedures. The new benchmarks were surveyed using Ashtech Z-Extreme, 12 channel dual-frequency GPS receivers. Full-phase carrier data were recorded on each occupied benchmark in Ashtech proprietary BIN format with daily occupations ranging from 6 to 12 hours. BIN files were then converted to RINEX-2 format for position processing.
    All static base station GPS sessions were submitted for processing to the online OPUS system software. The computed base location results were entered into a spreadsheet to compute one final positional coordinate and error analysis for that base location. The final positional coordinate (latitude, longitude, and ellipsoid height) is the weighted average of all GPS sessions. For each GPS session, the weighted average was calculated from the total session time in seconds; therefore, longer GPS occupation times held more value than shorter occupation times. Results were computed relative to ITRF00 coordinate system. The established geodetic reference frame for the project was WGS84. Therefore, final reference coordinates used to process the rover data were transformed from ITRF00 to WGS84 using National Oceanic and Atmospheric Administration/National Geodetic Survey(NOAA/NGS) HTDP software v2.1.
    OPUS results provide an error measurement for each daily solution. Applying these error measurements, the horizontal accuracy of the base station is estimated to be 0.04 (m) root mean squared (RMS).
    The kinematic (rover) trajectories were processed using Grafnav v8.1 software by Novatel, Inc. A horizontal error measurement, RMS is computed for each epoch. The horizontal trajectory errors for varied between 0 and 0.08(m).
    The combined horizontal error from base station coordinate solutions and rover trajectories range from 0 and 0.12 (m), with the average approximately 0.06 (m).
  3. How accurate are the heights or depths?
    The GPS antenna and receiver acquisition configuration used at the reference station was duplicated on the survey vessel (rover). The base receiver and the rover receiver record their positions concurrently at 1Hz recording intervals throughout the survey. All processed measurements are referenced to the base station coordinates.
    GPS base or differential reference stations were operated within approximately 15 to 20 km of the survey area. Two new temporary ground-control points or benchmarks (surveyed to within 1 cm to 2 cm accuracy) were established throughout the study area for use as reference receiver sites using standard benchmarks procedures. The new benchmarks were surveyed using Ashtech Z-Extreme, 12 channel dual-frequency GPS receivers. Full-phase carrier data were recorded on each occupied benchmark in Ashtech proprietary BIN format with daily occupations ranging from 6 to 12 hours. BIN files were then converted to RINEX-2 format for position processing.
    All static base station GPS sessions were submitted for processing to the online OPUS system software. The computed base location results were entered into a spreadsheet to compute one final positional coordinate and error analysis for that base location. The final positional coordinate (latitude, longitude, and ellipsoid height) is the weighted average of all GPS sessions. For each GPS session, the weighted average was calculated from the total session time in seconds; therefore, longer GPS occupation times held more value than shorter occupation times. Results were computed relative to ITRF00 coordinate system. The established geodetic reference frame for the project was WGS84. Therefore, final reference coordinates used to process the rover data were transformed from ITRF00 to WGS84 using National Oceanic and Atmospheric Administration/National Geodetic Survey(NOAA/NGS) HTDP software v2.1.
    OPUS results provide an error measurement for each daily solution. Applying these error measurements, the vertical accuracy of the base station is estimated to be 0.04 (m) root mean squared (RMS).
    The kinematic (rover) trajectories were processed using Grafnav v8.1 software by Novatel, Inc. A vertical error measurement, RMS is computed for each epoch. The vertical trajectory errors for varied between 0 and 0.08(m).
    The combined vertical error from base station coordinate solutions and rover trajectories range from 0 and 0.14 (m), with the average approximately 0.08 (m).
  4. Where are the gaps in the data? What is missing?
    These are complete post-processed x,y,z bathymetric data points with an acoustic single-beam system collected in 2011 on Lemon Bay, Florida area.
  5. How consistent are the relationships among the observations, including topology?
    This dataset was acquired on multiple research cruises in 2011 with identical hardware and software systems.

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)
    Mark E. Hansen
    U.S. Geological Survey
    Oceanographer
    600 Fourth St. South
    St. Petersburg, FL

    (727) 502-8000 (voice)
    (727) 502-8032 (FAX)
    mhansen@usgs.gov
  2. What's the catalog number I need to order this data set? Single-beam bathymetry, vessel (R/V Streeterville, R/V Catboat, jet-ski, and canoe) acquired bathymetric data.
  3. What legal disclaimers am I supposed to read?
    The data have no explicit or implied guarantees. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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 on any other system or for general or scientific purposes, 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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 18-Mar-2019
Metadata author:
U.S. Geological Survey
Attn: Mark Hansen
Oceanographer
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8000 (voice)
mhansen@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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