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Ediz Hook (Outside), Port Angeles Harbor, Washington, Bathymetry (Cruise ID: S-6-10-PS)

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Frequently anticipated questions:


What does this data set describe?

Title:
Ediz Hook (Outside), Port Angeles Harbor, Washington, Bathymetry (Cruise ID: S-6-10-PS)
Abstract:
Between February 22, 2010 and March 3, 2010 the U.S. Geological Survey, Pacific Coastal and Marine Science Center mapped the bathymetry and acoustic backscatter of the Elwha River Delta, Strait of Juan de Fuca, Washington State. In addition to the main survey, 3 small surveys of interest to USGS partners were conducted on February 26, 2010. The first is the area surrounding the abandoned Rayonier Pier site in Port Angeles Harbor, the second is a former log-storage facility on the southern side of Ediz Hook near the Port Angeles Coast Guard station. Both of these smaller surveys were conducted during a weather day where sea conditions were too rough for surveying outside the harbor breakwaters. In addition, several lines of data were collected on the outer face of Ediz hook as the vessel transited to and from the Elwha river delta to inspect failure features along the northen edge of Ediz Hook first observed in 2005 during USGS cruise K-1-05-PS.

The surveys were conducted using the research vessel R/V Parke Snavely outfitted with an interferometric sidescan sonar for swath mapping and Real-Time Kinematic navigation equipment for accurate shallow water operations.

Supplemental_Information:
The URL for USGS field activity S-6-10-PS is <http://walrus.wr.usgs.gov/infobank/s/s610ps/html/s-6-10-ps.meta.html> The URL for USGS field activity K-1-05-PS is <http://walrus.wr.usgs.gov/infobank/k/k105ps/html/k-1-05-ps.meta.html>
  1. How should this data set be cited?

    U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), Santa Cruz, CA., 2011, Ediz Hook (Outside), Port Angeles Harbor, Washington, Bathymetry (Cruise ID: S-6-10-PS): U.S. Geological Survey Open-File Report 1226.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -123.46975101499
    East_Bounding_Coordinate: -123.40117463619
    North_Bounding_Coordinate: 48.146453975694
    South_Bounding_Coordinate: 48.13610852976

  3. What does it look like?

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

    Beginning_Date: 22-Feb-2010
    Ending_Date: 03-Mar-2010
    Currentness_Reference: ground condition

  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 1122 x 5109, type grid cell

    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
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0

      Planar coordinates are encoded using row and column
      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 World Geodetic System 1984 (G1150).
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: World Geodetic System 1984 (G1150)
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values

  7. How does the data set describe geographic features?

    Altitude
    Altitude (elevation) above the WGS84 (G1150) ellipsoid in meters. Values are positive up. (Source: USGS)


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    USGS Pacific Coastal and Marine Science Center
    Attn: David P Finlayson
    Geologist
    U.S. Geological Survey
    Santa Cruz, CA 95060
    USA

    (831) 427-4757 (voice)
    (831) 427-4748 (FAX)
    dfinlayson@usgs.gov


Why was the data set created?

Inspect failure features along the northen edge of Ediz Hook first observed in 2005 during USGS cruise K-1-05-PS.


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: 22-Feb-2010 (process 1 of 6)
    Sonar Data Collection

    The bathymetric surveys were conducted using a 234.5 kHz SEA (Systems Engineering & Assessment Ltd) SWATHplus-M phase-differencing sidescan sonar. The sonar was pole-mounted on the 34-foot USGS mapping vessel R/V Parke Snavely, and affixed to a hull brace. Real-time kinematic (RTK) GPS position data were passed through a CodaOctopus F180 intertial measurement unit (IMU) to the sonar hardware and data collection software. Sonar heads, GPS antennae, and the IMU were surveyed in place to a common reference frame with a Geodimeter 640 Total Station. The R/V Snavely was outfitted with three networked workstations and a navigation computer for use by the captain and survey crew for data collection and initial processing.

    Date: 22-Feb-2010 (process 2 of 6)
    Geodetic Control

    Geodetic control for the survey was established using a shore based Global Positioning System (GPS) base station broadcasting Real Time Kinematic (RTK) corrections to the survey vessel via UHF radio link. The base station was located at the base of Ediz Hook. The base station was programmed using the WGS84 (G1150) reference frame with an Epoch of 2010.1548. Average Opus Solution coordinates for the station are:

    Reference Frame: WGS84 (G1150) Epoch: 2010.1548 Latitude: N 48 08 06.01943 Longitude: W 123 28 06.90674 Ellipsoid Height: -11.355m

    The average values for the derived OPUS solution for MILL are: Reference Frame: ITRF00 [same as WGS84 (G1150)] Epoch: 2010.1548 Latitude: N 48 08 06.01936 Longitude: W 123 28 06.90685 Ellipsoid Height: -11.351m

    The differences to be added to the RTK broadcast locations are: Latitude: -0.00007 Longitude: +0.00011 Ellipsoid Height: +0.004m

    Using UTM coordinates as a comparison: The base station was programmed using the following coordinates: Reference Frame: NAD83, UTM zone 10 Epoch: 2002.0000 Northing: 5331411.376m Easting: 465138.251m Ellipsoid Height: -11.042m Orthometric Height: 9.155m (based Geoid09)

    Date: 22-Feb-2010 (process 3 of 6)
    Vessel Position and Attitude

    The R/V Snavely was equipped with a CodaOctopus F180 attitude and positioning system for the duration of the survey. The F180 is running F190 firmware, and receives real-time kinematic (RTK) corrections directly. The RTK GPS data (2 cm error ellipse) are combined with the inertial motion measurements directly within the F190 hardware so that high-precision position and attitude corrections are fed in real-time to the sonar acquisition equipment. The WGS84 (G1150) Epoch 2010.1548 3-dimensional reference frame was used for all data acquisition.

    Date: 02-Feb-2010 (process 4 of 6)
    Sound Velocity Measurements

    Sound velocity measurements were collected continuously with an Applied Micro Systems Micro SV deployed on the transducer frame for real-time sound velocity adjustments at the transducer-water interface. The Micro SV is accurate to +/- 0.03 m/s. In addition, sound velocity profiles (SVP) were collected with an Applied Micro Systems, SvPlus 3472. This instrument provides time-of-flight sound-velocity measurements by using invar rods with a sound-velocity accuracy of 0.06 m/s, pressure measured by a semiconductor bridge strain gauge to an accuracy of 0.15 percent (Full Scale) and temperature measured by thermistor to an accuracy of 0.05 degrees Celsius (Applied Microsystems Ltd., 2005).

    Date: 02-Feb-2010 (process 5 of 6)
    Sonar Sounding Processing

    GPS data and measurements of vessel motion are combined in the F180 hardware to produce a high-precision vessel attitude packet. This packet is transmitted to the Swath Processor acquisition software in real-time and combined with instantaneous sound velocity measurements at the transducer head before each ping. Up to 20 pings per second are transmitted with each ping consisting of 2048 samples per side (port and starboard). The returned samples are projected to the seafloor using a ray-tracing algorithm working with the previously measured sound velocity profiles in SEA Swath Processor (version 3.05.18.04). A series of statistical filters are applied to the raw samples that isolate the seafloor returns from other uninteresting targets in the water column. Finally, the processed data is stored line-by-line in both raw (.sxr) and processed (.sxp) trackline files. Processed (.sxp) files were further processed with sxpegn (build 151) by David Finlayson (USGS) to remove erroneous data from the files and make valid gain-normalized amplitude data for processing backscatter data.

    Date: 20-Mar-2011 (process 6 of 6)
    Digital Elevation Model Production

    The digital elevation model (DEM) produced in this work is solely derived from the bathymetric data collected by the USGS during field activity S-6-10-PS. CARIS HIPS and SIPS (version 7.0.2 Service Pack 2) was used to clean and bin the raw bathymetry. Processed .sxp files were imported to CARIS, and field sheets were created within CARIS to encompass the survey area.

    Survey lines were filtered to remove adjacent line data from nadir gaps. A CARIS Swath Angle BASE (Bathymetric with Associated Statistical Error) surface was created at 1 m resolution and the subset editor was used to clean artifacts and other unwanted soundings. The binned data were exported as an ASCII table along with calculations of the bin standard deviation (of all soundings within the 1 m x 1 m cell spacing) and the sounding density.

    Finally, the ASCII data were gridded in Surfer at 1-m resolution using the IDW algorithm with a 3 m search radius and a smoothing parameter set to 0.25 (the smoothing parameter here accounts for the horizontal uncertainty in the sounding position). This process filled small gaps in the surface and provided some minor smoothing through the statistical noise inherent to interferometric bathymetry. This surface was converted to ESRI ASCII grid format using Surfer's conversion tools.

  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?

    This bathymetric data has not been independently verified for accuracy.

  2. How accurate are the geographic locations?

    Uncertainty in the horizontal position of each sounding is a function of the total uncertainty propagated through each of the following component instruments: 1) base station GPS, 2) vessel GPS, 3) intertial motion unit (IMU), 4) water sound velocity model, and 5) beam spreading in the water column. Assuming no systematic errors in the measurement instruments themselves, beam spreading is the dominate source of positional uncertainty. The 1-degree sonar beam of the SWATHplus-M results in horizontal uncertainty ranging from 0.10 m at 10 m slant range, to about 0.45 m at 50 m slant range.

  3. How accurate are the heights or depths?

    After filtering the data to remove obvious outliers, the standard deviation of the remaining sounding elevations was calculated for each 1 m x 1 m cell (each containing 28 soundings on average) in CARIS. The mean standard deviation for all cells in the survey is 0.18 m and 95% of the cells in the data set have a standard deviation of less than 0.50 m.

  4. Where are the gaps in the data? What is missing?

    These data consist of 4 survey lines collected as time allowed during transites to and from the main survey area to the west near the Elwha River. The first line extends along much of the north side of Ediz Hook and was used to identify the top of slump features first identified during USGS cruise K-1-05-PS. The remaining 3 lines were used to fill in as much detail as possible over the slump features. At the base of the spit (around 60 m depth) there is a data gap, otherwise most of the area of interest was ensonified.

  5. How consistent are the relationships among the observations, including topology?

    All bathymetric values are derived from the same instruments and processing workflow.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
If physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: <http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html>
Use_Constraints:
Not suitable for navigation.

Read and fully comprehend the metadata prior to data use.

Acknowledge the U.S. Geological Survey (USGS), the Originator, when using the data set as a source. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Share data products developed using the source data set with the Originator.

Data should not be used beyond the limits of the source scale.

This information is not intended for navigational purposes.

The data set is NOT a survey document and should not be utilized as such. Some USGS information accessed through this means may be preliminary in nature and presented without the approval of the Director of the USGS.

This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the responsibility of the user.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey, Pacific Coastal and Marine Science Center (PCMSC)
    Attn: David P Finlayson
    U.S. Geological Survey
    Santa Cruz, CA 95060-5792
    US

    831-427-4757 (voice)
    831-427-4748 (FAX)
    dfinlayson@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    This information is not intended for navigational purposes.

    Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

    Please recognize the U.S. Geological Survey (USGS) as the source of this information. Physical materials are under controlled on-site access. Some USGS information accessed through this means may be preliminary in nature and presented without the approval of the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the responsibility of the user.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 11-Apr-2011
Metadata author:
Pacific Coastal and Marine Science Center (PCMSC), US Geological Survey
U.S. Geological Survey
Santa Cruz, California 95060
USA

8314274757 (voice)
dfinlayson@usgs.gov

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


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