Multibeam bathymetric data collected in the eastern Gulf of Alaska during USGS Field Activity 2016-625-FA using a Reson 7160 multibeam echosounder (10 meter resolution, 32-bit GeoTIFF, UTM 8 WGS 84, WGS 84 Ellipsoid)

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?
   U.S. Geological Survey, 20221101, Multibeam bathymetric data collected in the eastern Gulf of Alaska during USGS Field Activity 2016-625-FA using a Reson 7160 multibeam echosounder (10 meter resolution, 32-bit GeoTIFF, UTM 8 WGS 84, WGS 84 Ellipsoid): data release DOI:10.5066/P9BTWEXK, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

   Online Links:

   • https://doi.org/10.5066/P9BTWEXK
   • https://www.sciencebase.gov/catalog/item/5d8cebe8e4b0c4f70d0c8036

   This is part of the following larger work.
   Andrews, Brian D., Brothers, Daniel S., Uri S. ten Brink, Kluesner, Jared W., Haeussler, Peter J., Wyland, Robert M., and Currie, Jackson E., 2022, Multibeam bathymetric and backscatter data collected in the eastern Gulf of Alaska along the Queen Charlotte Fault, U.S. Geological Survey Field Activity 2016-625-FA: data release DOI:10.5066/P9BTWEXK, U.S. Geological Survey, Reston, Virginia.

   Online Links:

   • https://doi.org/10.5066/P9BTWEXK
   • https://www.sciencebase.gov/catalog/item/5d8cb824e4b0c4f70d0c7c74

   Other_Citation_Details:

   Suggested citation: Andrews, B.D., Brothers, D.S., ten Brink, U.S., Kluesner, J. W., Haeussler, P.J., Wyland, R. M., and Currie, J.E., 2022, Multibeam bathymetry and backscatter data collected in the eastern Gulf of Alaska along the Queen Charlotte Fault, U.S. Geological Survey Field Activity 2016-625-FA: U.S. Geological Survey data release, https://doi.org/P9BTWEXK

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -136.913215
   East_Bounding_Coordinate: -134.338608
   North_Bounding_Coordinate: 58.023711
   South_Bounding_Coordinate: 55.031169
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/5d8cebe8e4b0c4f70d0c8036?name=2016_625_FA_Reson7160_Bathymetry_10m_browse.jpg (JPEG)

   quick view image of 10-m bathymetric grid of Queen Charlotte Fault area, Eastern Gulf of Alaska.

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 18-May-2016

   Ending_Date: 11-Jun-2016

   Currentness_Reference:

   Data were collected on the following dates: 20160522-20160528 (Julian days 142-149, 20160530-20160611 (Julian days 151-163). No data were collected 20160529 (Julian day 150) during crew change in Sitka AK.

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. It contains the following raster data types:
      • Dimensions 14797 x 33850 x 1, type Pixel
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 8
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -135.000000
      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 10.000000
      Ordinates (y-coordinates) are specified to the nearest 10.000000
      Planar coordinates are specified in meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      

      Vertical_Coordinate_System_Definition:

      Altitude_System_Definition:

      Altitude_Datum_Name: World Geodetic Dataum 1984
      Altitude_Resolution: 0.1
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:

      Explicit elevation coordinate included with horizontal coordinates

7. How does the data set describe geographic features?

   Entity_and_Attribute_Overview:

   Elevation values represent elevation in meters referenced to the WGS 84 ellipsoid. Values range between 107.28 and 2137.3 meters (WGS 84). The GeoTIFF is a 32-bit image where the pixel values correspond to depth values.

   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)
   • U.S. Geological Survey
2. Who also contributed to the data set?
   Please recognize the U.S. Geological Survey (USGS) as the source of this information. Data was collected aboard Alaska Department of Fish and Game’s R/V Medeia and would not be possible without the support of vessel crew members Jim deLa Bruere, Craig Conger, Cedar Stark, and Becky Wilson.
3. To whom should users address questions about the data?
   Brian D. Andrews

   U.S. Geological Survey

   Geographer

   384 Woods Hole Road

   Woods Hole, Massachusetts
   

   USA

   508-548-8700 x2348 (voice)

   508-457-2310 (FAX)

   bandrews@usgs.gov

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?

   RAW RESON 7160 MULTIBEAM ECHOSOUNDER FILES (.raw, s7k, 7k, HSX) (source 1 of 1)

   Balster-Gee, Alicia F., Andrews, Brian D., Brothers, Daniel S., Uri S. ten Brink, Kluesner, Jared W., and Haeussler, Peter J., 2017, Multibeam bathymetry and backscatter data and multichannel sparker seismic-reflection data between Cross Sound and Dixon Entrance, offshore southeastern Alaska, collected from 2016-05-17 to 2016-06-12 during field activity 2016-625-FA: data release DOI:10.5066/F7NG4PTW, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/F7NG4PTW

   Type_of_Source_Media: disc
   Source_Contribution:

   Sonar Configuration: Bathymetry data were collected using a Reson SeaBat 7160 multibeam echosounder operating at a frequency of 44 kHz. The sonar transducer was mounted from the starboard side of the R/V Medeia about 2 meters below the waterline. Vessel attitude was recorded using an Applanix POS MV 320 V5 to provide attitude and positioning that was mounted on the centerline of the vessel. Data were collected using the Reson 7k Control Center and HYPACK (v. 2016). Speed of sound was recorded at 5-8 hour intervals using a Oceanscience RapidCAST SV system mounted on the starboard quarter. Navigation was recorded using Differential Global Positioning System and a Hemisphere MBX-4 GPS receivers mounted above the bridge.

2. How were the data generated, processed, and modified?

   Date: May-2016 (process 1 of 4)

   STEP 1: DATA ACQUISITION multibeam bathymetry data were collected along the Queen Charlotte fault in southeast Alaska using a Reson SeaBat 7160 multibeam sonar operating at a frequency of 44 kHz that was mounted on wing-mount from the starboard side of the R/V Medeia owned and operated by the Alaska Department of Fish and Game. The sonar collected depth, backscatter (time series), and water column data along approximately 4178 kilometers of survey lines oriented parallel with the gradient of the continental shelf west of Chichagof and Baranof islands in southeast Alaska. Data were collected using the Reson 7k Control Center and HYPACK (v. 2016).
   TerraSond LLC of Seattle Washington was responsible for leasing, mobilizing and operating all equipment related to the Reson 7160. Doug MacGillivray and David Maggio of TerraSond were in charge of all multibeam data acquisition. The contact person for this and all subsequent processing steps below is Brian D. Andrews. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Brian D. Andrews

   Geographer

   384 Woods Hole Rd.

   Woods Hole, MA
   

   USA

   508-548-8700 ext. 2348 (voice)

   508-457-2310 (FAX)

   bandrews@usgs.gov

   Data sources produced in this process:

   • .Raw, s7k, 7k, HSX

   Date: May-2016 (process 2 of 4)

   STEP 2: IMPORT RAW BATHYMETRY FILES TO CARIS HIPS.
   Multibeam bathymetry processing within CARIS HIPS (v. 9.1.1) during the survey consisted of the following flow:
   1) Vessel configuration file was created in CARIS (RVMedeia.hvf) which includes, linear and angular installation offsets and vendor specified uncertainty values for each of the survey sensors.
   2) A CARIS HIPS project (v. 9.1.1) was created with projection information set to Universal Transverse Mercator (UTM) Zone 8N, WGS 84.
   3) Each survey line was recorded to both a Reson .s7k, and a Hypack (v. 2016) .HSX, .RAW, and .7k files. The Hypack .HSX files were imported to the new CARIS project using the Import/Conversion Wizard.
   4) Delayed heave data from raw POS MV files were used to update HIPS survey lines using the import auxiliary data function.
   5) Navigation was reviewed and edited as needed using the Navigation Editor tool.
   6) Sound velocity correction was applied using the CARIS algorithm, a master SVP file containing all the sound velocity profiles collected during the survey and specifying the nearest in distance method, delayed heave source, and use surface sound speed.
   7) Data were merged selecting "no tide" and the delayed heave source.
   8) Total Propagated Uncertainty (TPU) was calculated for each line file using the manufacturer's offset values in the vessel configuration file.
   9) A 10-m resolution depth surface was created using the Combined Uncertainty Bathymetric Estimator (CUBE) method for each of the six blocks. Surfaces were reviewed for inconsistencies and anomalies. The swath and subset editors were used to remove spurious points through manual editing and filter application, and the refraction editor was used to adjust sound speed values in areas where velocimeter data did not adequately correct depth profiles, which were obviously influenced by local anomalies in speed of sound through the water column.
   10) Survey lines adjusted for refraction anomalies were remerged, and the respective CUBE surfaces were recomputed to reflect the changes. Processing during the survey was primarily focused on QA/QC during acquisition. Editing processes required trial and error, and were at times iterative. Data sources produced in this process:

   • CARIS HIPS line files.

   Date: Oct-2016 (process 3 of 4)

   STEP 3: APPLY POST PROCESSED SBET FILES AND EDIT SOUNDINGS.
   Vessel attitude data were processed using PosPac (v. 7.2) after the final ephemeris data were available 2 weeks after completion of the survey.
   1) Post-processed navigation, vessel attitude, and GPS height data from POSPac SBET files, and post-processed RMS attitude error data from POSPac smrmsg files were used to update HIPS survey lines using the import auxiliary data function.
   2) Navigation source was set to Applanix SBET, and navigation was reviewed and edited as needed using the Navigation Editor tool.
   3) GPS tide was computed using the post-processed delayed heave data, the vessel water line, and a single datum value of 0 m (vertically referencing the data to the WGS 84 Ellipsoid)
   4) Sound velocity correction was reapplied using the CARIS algorithm, the master SVP file containing all the sound velocity profiles collected during the survey and specifying the nearest in time method, delayed heave source, and use surface sound speed.
   5) Data were remerged selecting the GPS tide and delayed heave sources.
   6) New CUBE surfaces were created for each of the 6 survey blocks and interpolated to fill small "no data" gaps. Data sources used in this process:

   • Processed sbet files(.000)

   Data sources produced in this process:

   • CARIS line files

   Date: 17-Mar-2017 (process 4 of 4)

   STEP 4: EXPORT HIPS CUBE SURFACE TO GEOTIFF
   The final version of the six individual CUBE surfaces were combined into a single CSAR surface and then exported to a 32-bit GeoTIFF. The output projection of the GeoTIFF used UTM Zone 8, WGS 84. Data sources used in this process:

   • 2016-625-FA_10mCube.csar

   Data sources produced in this process:

   • 2016-625-FA_Reson716_Bathymetry_10m.tiff

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?
   The horizontal accuracy of these data is +/- 1.05 meters as reported by subcontractor TerraSond.
3. How accurate are the heights or depths?
   Vertical accuracy of the raw data based on system specifications may be approximately 1 percent of water depth (ranging from 1 to 21.4 meters based on the water depth range of 100 meters to approximately 2137 meters within the survey area). The Applanix Wavemaster POS MV Attitude and Positioning system, used to correct for vessel roll, pitch, heave, and yaw, has a theoretical vertical accuracy of a few mm. Post-Processed Kinematic (PPK) GPS height corrections (from Applanix POSPac smoothed best estimate of trajectory (SBET) files) were used to reference soundings to the World Geodetic System 1984 (WGS 84) ellipsoid and remove fluctuations in sea surface elevations during the survey. 120 sound speed profiles acquired using either a RapidSV or RapidCTD sound velocity profiler were used during processing to minimize acoustic refraction artifacts in the bathymetry data. An expendable bathythermograph (XBT) was used to sample speed of sound in deeper waters. Changes in vessel draft due to water and fuel usage were not considered.
4. Where are the gaps in the data? What is missing?
   This grid does not include all the data collected during this survey. Portions of cross and transit lines are not included. Three lines inshore (149_010_0003, 149_010_0049, 149_112_0533) collected in Whale Bay, Baranof Island, during heavy weather offshore are not included in this grid.
5. How consistent are the relationships among the observations, including topology?
   This grid represents processed Reson 7160 multibeam echosounder (MBES) bathymetry data gridded at 10-m resolution. Quality control and data processing conducted to remove spurious points and reduce sound speed artifacts (refraction) using Computer Aided Resource Information System (CARIS) Hydrographic Information Processing System (HIPS v. 9.1.1).

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

   Denver, CO
   

   1-888-275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? FileName.zip: ZIP file contains the 32-bit GeoTIFF (2016-625-FA_Reson7160_Bathymetry_10m.tif), 2016-625-FA_Reson7160_Bathymetry_10mBrowse.jpg browse graphic, and the associated FGDC CSDGM metadata in XML, HTML, FAQ, and text formats.
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 USGS 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:	This WinZip (v. 14.0) file contains a GeoTIFF of Queen Charlotte Fault Area and metadata. in format GeoTIFF (version CARIS HIPS v. 9.3.1) GeoTIFF image Size: 154
     Network links:	https://www.sciencebase.gov/catalog/file/get/5d8cebe8e4b0c4f70d0c8036 https://www.sciencebase.gov/catalog/item/5d8cebe8e4b0c4f70d0c8036 https://doi.org/10.5066/P9BTWEXK

   • Cost to order the data: none

5. What hardware or software do I need in order to use the data set?
   To utilize this data, the user must have software capable of reading a 32-bit GeoTIFF.

Who wrote the metadata?

Dates:

Last modified: 01-Nov-2022

Metadata author:

Brian D. Andrews

U.S. Geological Survey

Geographer

384 Woods Hole Rd.

Woods Hole, MA

USA

508-548-8700 x2348 (voice)

508-457-2310 (FAX)

bandrews@usgs.gov

Metadata standard:

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