Bathymetry at Kotzebue, Alaska, July 2024

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?
   Gibbs, Ann E., Engelstad, Anita C., Over, Jin-Si R., Buzard, Richard M., Snyder, Alexander G., and Nereson, Alexander L., 20260313, Bathymetry at Kotzebue, Alaska, July 2024: data release DOI:10.5066/P13YIWKC, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P13YIWKC

   This is part of the following larger work.
   Erikson, Li, Gibbs, Ann E., Buzard, Richard M., Nowacki, Daniel J., Snyder, Alexander G., Engelstad, Anita C., Johnson, Cordell, Nereson, Alexander L., Over, Jin-Si R., Russel, Paul, and Lyons, Colin, 2025, In situ field data, Coastal Alaska, 2023 to 2025 (ver. 2.0, March 2026): data release DOI:10.5066/P13YIWKC, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P13YIWKC

   Other_Citation_Details:

   Suggested Citation: Erikson L.H., Gibbs A.E., Buzard R.M., Nowacki D.J., Snyder A.G., Engelstad A.C., Johnson C., Nereson A.L., Over J.R., Russel, P., Lyons, C., 2025, In situ field data, Coastal Alaska 2023 to 2025 (ver. 2.0, March 2026): U.S. Geological Survey data release, https://doi.org/10.5066/P13YIWKC.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -162.6202721
   East_Bounding_Coordinate: -162.5320066
   North_Bounding_Coordinate: 66.9245172
   South_Bounding_Coordinate: 66.8916359
   

3. What does it look like?

   kotzebue_2024_bathy_browse.png (PNG)

   Satellite image overlain with bathymetry data points collected offshore of Kotzebue, Alaska in July 2024.

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

   Calendar_Date: 10-Jul-2024

   Currentness_Reference:

   ground condition at the time source data were collected

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

   Geospatial_Data_Presentation_Form: comma-delimited text
   

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 (184780)
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 3
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -165.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in meters
      The horizontal datum used is D NAD 1983 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.
      
7. How does the data set describe geographic features?

   bathymetry_kotzebue_20240710.csv

   Comma Separated Value (CSV) file containing data. (Source: Producer Defined)

   Longitude

   Longitude in decimal degrees, WGS 1984 (Source: Producer Defined)

   Range of values
   Minimum:	-162.6202721
   Maximum:	-162.5320066
   Units:	decimal degrees
   Resolution:	0.0000001

   Latitude

   Latitude in decimal degrees, WGS 1984 (Source: Producer Defined)

   Range of values
   Minimum:	66.8916359
   Maximum:	66.9245172
   Units:	decimal degrees
   Resolution:	0.0000001

   Easting_m_UTM

   X coordinate (easting) in meters NAD83(2011) / UTM zone 3N (EPSG: 6332) (Source: Producer Defined)

   Range of values
   Minimum:	604177.02
   Maximum:	607978.28
   Units:	meters
   Resolution:	0.01

   Northing_m_UTM

   Y coordinate (northing) in meters NAD83(2011) / UTM zone 3N (EPSG: 6332) (Source: Producer Defined)

   Range of values
   Minimum:	7421341.14
   Maximum:	7425060.15
   Units:	meters
   Resolution:	0.01

   Elevation_m_NAVD88

   Orthometric height (elevation) in meters NAVD88 GEOID12B (Source: Producer Defined)

   Range of values
   Minimum:	-17.86
   Maximum:	0.84
   Units:	meters
   Resolution:	0.01

   Elevation_Uncertainty_m

   Estimated elevation uncertainty in meters (Source: Producer Defined)

   Range of values
   Minimum:	0.05
   Maximum:	0.59
   Units:	meters
   Resolution:	0.01

   UTM_Zone

   UTM Zone in NAD83(2011) / UTM zone 3N (EPSG: 6332) (Source: Producer Defined)

   Value	Definition
   3N	UTM Zone 3 North

   Entity_and_Attribute_Overview:

   These metadata describe a comma-separated value (csv) file containing nearshore and inland bathymetry data from Kotzebue, Alaska. The first line is a header line and each subsequent line contains x and y coordinates in decimal degrees WGS 84 (EPSG: 4326), x and y coordinates in meters NAD83(2011) / UTM zone 3N (EPSG: 6332), an orthometric height (elevation) in meters NAVD88 GEOID12B, the uncertainty associated with orthometric height, in meters, and the UTM zone used (3N).

   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)
   • Ann E. Gibbs
   • Anita C. Engelstad
   • Jin-Si R. Over
   • Richard M. Buzard
   • Alexander G. Snyder
   • Alexander L. Nereson
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: 10-Jul-2024 (process 1 of 3)

   Single-beam bathymetry data were collected on July 10, 2024, using a survey-grade echosounder. The system consisted of a CEE HydroSystems CEESCOPE with a 200 kHz transducer (9-degree beam angle) and a Trimble GNSS receiver. The transducer and receiver were attached to the bottom and top (respectively) of a 2.20 meter-long survey rod. The rod was mounted to the side of a 25 ft aluminum work skiff using an adjustable angle bracket. The rod was rotated to a vertical position using a bubble level once the skiff was underway and lowered into the water so the transducer was submerged to a depth of 20 cm. GNSS positions were logged at 10 Hz while traveling at a target speed of under 3 meters per second. Wind conditions were light with 1 ft waves.

   Date: 20-Aug-2024 (process 2 of 3)

   Survey positions were post-processed using a base station and differential post-processing. The position of the GNSS base station was derived from a static GNSS occupation on July 10, 2024. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS) and averaged to derive the final base station coordinates relative to the North American Datum of 1983 (2011 realization). Positioning data from the GNSS receiver on the vessel was post-processed using Waypoint Grafnav to apply differential corrections from the GNSS base station. Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey GEOID12B offsets. Bathymetric soundings were merged with post-processed positioning data and spurious soundings were removed using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB.

   Date: 24-Nov-2025 (process 3 of 3)

   All available bathymetry data from the survey were compiled into a comma-delimited text file for distribution.

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?
   The estimated horizontal uncertainty of survey points is 0.05 m. Positions of the work skiff from which the survey was conducted were obtained with a survey-grade global navigation satellite system (GNSS) receiver and a GNSS base station. The GNSS base station was set up on an existing benchmark on land (ID BBDY64) during the bathymetry survey. Base station GNSS RINEX files were uploaded to the National Geodetic Survey Online Positioning User Service (OPUS) to derive the final base station coordinates relative to the North American Datum of 1983 (2011 realization). The resulting solutions were compared to the existing coordinates for the benchmark and found to be within 1 cm of published coordinates. Positioning data from the survey vessels were post-processed using Waypoint Grafnav to apply differential corrections from the GNSS base station. Uncertainty in the horizontal positions due to vessel pitch and roll is unquantified but expected to be low given light winds and small waves (less than 1 foot).
3. How accurate are the heights or depths?
   The estimated vertical uncertainty of survey points is included in the dataset ("Elevation_Uncertainty_m") and ranges from 0.05 to 0.59 m. These values were calculated by summing in quadrature the uncertainties from GNSS positioning, echosounder measurements, and modeled sound speed in water. Manufacturer-reported uncertainty for differentially corrected Trimble GNSS rover positions is 1.5 cm plus 1 ppm of the survey baseline, combined with the vertical accuracy of the NGS OPUS-derived GNSS base station position. The single-beam echosounder used in this study has a reported vertical accuracy of 1 cm. The speed of sound in water was not measured during this survey, but it was modeled using representative Arctic coastal temperature and salinity ranges; this uncertainty increases with depth. Vertical error due to vessel pitch and roll was not quantified but is expected to be low given light winds and waves less than 1 ft. Pitch and roll under 4.5 degrees do not affect depth readings for the 9-degree beam transducer, assuming a vertical antenna/transducer installation and relatively flat seafloor. For larger pitch/roll values the depth measurement increases only slightly: a pitch/roll of 20 degrees (effective beam tilt of 15.5 degrees) would increase depth readings by only approximately 3.8 percent.
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 - CMGDS

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov
2. What's the catalog number I need to order this data set? These data are available in a comma-separated value format (csv) accompanied by 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:	comma-delimited text file in format Comma-delimited text (version Microsoft Excel (version 2408 (Build 17928.20538 Click-to-Run))) Size: 10.6
     Network links:	https://doi.org/10.5066/P13YIWKC

   • Cost to order the data: None

5. What hardware or software do I need in order to use the data set?
   These data can be opened with any text viewer, spreadsheet editor, or geographic information systems (GIS) software.

Who wrote the metadata?

Dates:

Last modified: 13-Mar-2026

Metadata author:

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

Metadata standard:

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