Acoustic-backscatter data from Floras Lake, Oregon, June 2018

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?
   SeanPaul M. La Selle, Stevens, Andrew W., and Nasr, Brandon M., 20230213, Acoustic-backscatter data from Floras Lake, Oregon, June 2018: data release DOI:10.5066/P9FQQ5JN, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P9FQQ5JN
   • https://www.sciencebase.gov/catalog/item/5e8bcdb082cee42d13444321

   This is part of the following larger work.
   SeanPaul M. La Selle, Stevens, Andrew W., and Nasr, Brandon M., 2023, Bathymetry and acoustic backscatter data from Floras Lake, Oregon, June 2018: data release DOI:10.5066/P9FQQ5JN, U.S. Geological Survey, Santa Cruz, CA.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -124.5099660
   East_Bounding_Coordinate: -124.4960940
   North_Bounding_Coordinate: 42.9029970
   South_Bounding_Coordinate: 42.8841060
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 19-Jun-2018

   Ending_Date: 20-Jun-2018

   Currentness_Reference:

   ground condition at time data were collected

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

   Geospatial_Data_Presentation_Form: GeoTIFF
   

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: 10
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.00000
      Latitude_of_Projection_Origin: 0.00000
      False_Easting: 500000.0
      False_Northing: 0.00
      

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 1983.
      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.
      
7. How does the data set describe geographic features?

   value

   backscatter intensity as a digital number (Source: Producer defined)

   Entity_and_Attribute_Overview:

   The complete 0.5-m resolution 2018 Floras Lake backscatter grid was originally archived as a TIFF image with the following attributes.

   Cell size = 0.5
   Number of rows = 7217
   Number of columns = 4005
   
   Data type = floating point
   NO_DATA_VALUE = -999
   
   Boundary
   Xmin = 375523.75
   Xmax = 379132.25
   Ymin = 4749038.75
   Ymax = 4751041.25
   
   Statistics
   Minimum value = 6.6
   Maximum value = 102.5
   Mean = 36.7
   Standard deviation = 5.2
   
   Coordinate system description
   Projection  UTM
   Zone  10
   Datum  NAD83
   Units  meter
   

   Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • SeanPaul M. La Selle
   • Andrew W. Stevens
   • Brandon M. Nasr
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   PCMSC Science Data Coordinator

   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@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: 20-Jun-2018 (process 1 of 2)

   Acoustic-backscatter data were collected on June 20, 2018, using a sidescan sonar system and global navigation satellite systems (GNSS) receivers mounted on personal watercraft (PWC). The sonar system consisted of a Tritech Starfish 990F sidescan sonar system with a 1-MHz transducer and a 0.3-degree horizontal beam width. Positioning of the survey vessels was determined at 10 Hz using survey-grade GNSS receivers. Output from the GNSS receivers and sonar systems were combined in real time on the PWC by a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing PWC operators to navigate along survey lines at speeds of 2 to 3 m/s.

   Date: 21-Jun-2018 (process 2 of 2)

   Survey-grade positions of the PWCs were achieved with a single-base station and differential post-processing. Positioning data from the GNSS receivers were post-processed using Waypoint Grafnav to apply differential corrections from a GNSS base station with known horizontal and vertical coordinates relative to the North American Datum of 1983. Acoustic-backscatter data were merged with post-processed positioning data, and backscatter files were adjusted to minimize the effect of aquatic vegetation, and spurious soundings were removed using SonarWiz software (version 6). Processed backscatter grids were exported as a GeoTIFF and projected in cartesian coordinates using the Universal Transverse Mercator (UTM), Zone 10 North, meters coordinate system.

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?
   No formal attribute accuracy tests were conducted.
2. How accurate are the geographic locations?
   Survey-grade positions of the personal watercraft (PWCs) were achieved with global navigation satellite system (GNSS) receivers and a single GNSS base station placed on a benchmark coordinates relative to the North American Datum of 1983. The position and elevation of the benchmark were derived from two static GNSS occupations on June 19 and 20, 2018, with durations of 7 and 6 hours, respectively. The equipment for the static occupations consisted of a Trimble R10 GNSS receiver and fixed-height tripod. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS). The processed positions from each occupation were averaged to attain the final coordinates of the benchmark with an average horizontal accuracy of 1 cm. Positioning data from the PWCs were post-processed using Waypoint Grafnav software to apply differential corrections from the GNSS base station. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GNSS rover trajectories is 0.8 cm + 0.5 ppm. Baselines from the GNSS base station varied between 100 m and 2.5 km with a mean of 1 km, suggesting the average horizontal accuracy of survey vessel positions to be about 1 cm. Combining the uncertainty in the benchmark and watercraft yields a total uncertainty of 2 cm. Uncertainty in the horizontal positions associated with pitch and roll of the survey vessels is unknown. Accuracies of final products may be lower due to total propagated uncertainties of the mapping systems, which include sonar system, GNSS system, and navigation, as well as data processing that includes sounding cleaning, and gridding.
3. How accurate are the heights or depths?
   Not applicable to acoustic-backscatter data
4. Where are the gaps in the data? What is missing?
   Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
5. How consistent are the relationships among the observations, including topology?
   All data fall within expected ranges.

How can someone get a copy of the data set?

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

   U.S. Geological Survey

   Denver Federal Center, Building 810, Mail Stop 302

   Denver, CO
   

   USA

   1-888-275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? These data are available in GeoTIFF format, including a tif world file (.tfw) and CSDGM FGDC-compliant metadata.
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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Downloadable zip file contains the TIFF (.tif) version of the backscatter data and a projection file (.tfw). in format GeoTIFF (version ArcMap (version 10.3.1)) Size: 12.72
     Network links:	https://www.sciencebase.gov/catalog/file/get/5e8bcdb082cee42d13444321 https://www.sciencebase.gov/catalog/item/5e8bcdb082cee42d13444321 https://doi.org/10.5066/P9FQQ5JN

   • Cost to order the data: None

Who wrote the metadata?

Dates:

Last modified: 13-Feb-2023

Metadata author:

PCMSC Science Data Coordinator

U.S. Geological Survey, Pacific Coastal and Marine Science Center

2885 Mission St.

Santa Cruz, CA

831-427-4747 (voice)

pcmsc_data@usgs.gov

Metadata standard:

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