Bathymetry--Offshore of Refugio Beach Area, California

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Frequently anticipated questions:


What does this data set describe?

Title: Bathymetry--Offshore of Refugio Beach Area, California
Abstract:

This part of SIM 3319 presents data for the bathymetry and shaded-relief maps (see sheets 1, 2, SIM 3319) of the Offshore of Refugio Beach map area, California. The raster data file for the bathymetry map is included in "Bathymetry_OffshoreRefugioBeach.zip," which is accessible from <https://pubs.usgs.gov/ds/781/OffshoreRefugioBeach/data_catalog_OffshoreRefugioBeach.html>.
The bathymetry and shaded-relief maps of Offshore of Refugio Beach Area, California, were generated from bathymetry data collected by the U.S. Geological Survey (USGS), and by Fugro Pelagos, for the U.S. Army Corps of Engineers (USACE) Joint Lidar Bathymetry Technical Center of Expertise. The offshore region was mapped by the USGS in 2008, using a 234.5-kHz SEA (AP) Ltd. SWATHplus-M phase-differencing sidescan sonar. The nearshore bathymetry and coastal topography were mapped for USACE by Fugro Pelagos in 2009, using the SHOALS-1000T bathymetric-lidar and Leica ALS60 topographic-lidar systems. All these mapping missions combined to collect bathymetry from the 0-m isobath to beyond the 3-nautical-mile limit of CaliforniaĦs State Waters.
Supplemental_Information:
Information for the related USGS Pacific Coastal and Marine Science Center data collection field activity, S-8-08-SC online at <http://walrus.wr.usgs.gov/infobank/s/s808sc/html/s-8-08-sc.meta.html>.
  1. How should this data set be cited?

    Dartnell, Peter, Phillips, Eleyne L., and Finlayson, David P., 2015, Bathymetry--Offshore of Refugio Beach Area, California:.

    This is part of the following larger work.

    Johnson, Samuel Y., Dartnell, Peter, Cochrane, Guy R., Golden, Nadine E., Phillips, Eleyne L., Ritchie, Andrew C., Krigsman, Lisa M., Dieter, Bryan E., Conrad, James E., Greene, H. Gary, Seitz, Gordon G., Endris, Charles A., Sliter, Ray W., Wong, Florence L., Erdey, Mercedes D., Gutierrez, Carlos I., Yoklavich, Mary M., Draut, Amy E., and Hart, Patrick E., 2015, California State Waters Map Series--Offshore of Refugio Beach Area, California: Scientific Investigations Map SIM 3319, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -120.19
    East_Bounding_Coordinate: -119.99
    North_Bounding_Coordinate: 34.55
    South_Bounding_Coordinate: 34.38

  3. What does it look like?

    <https://pubs.usgs.gov/ds/781/OffshoreRefugioBeach/images/Bathymetry_OffshoreRefugioBeach.jpg> (JPEG)
    Bathymetry imagery offshore Refugio Beach.

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

    Calendar_Date: 2015
    Currentness_Reference: Publication Date

  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. It contains the following raster data types:

      • Dimensions, 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: -123.00000
      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 2.0
      Ordinates (y-coordinates) are specified to the nearest 2.0
      Planar coordinates are specified in Meters

      The horizontal datum used is WGS84.
      The ellipsoid used is NAVD88.
      The semi-major axis of the ellipsoid used is 6378137.00 meters.
      The flattening of the ellipsoid used is 1/298.257223563.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The complete 2-m resolution bathymetry grid of Offshore Refugio Beach was originally archived as an ESRI grid with the following attributes:
    Cell size = 2.0
    Number of rows = 8960
    Number of columns = 8960
    
    Data type = floating point
    
    Boundary
    Xmin = 758070.0
    Xmax = 775990.0
    Ymin = 3808160.0
    Ymax = 3826080.0
    
    Statistics
    Minimum value = -146.38
    Maximum value = 1.33
    Mean = -59.97
    Standard deviation = 26.04
    
    Coordinate system description
    Projection  UTM
    Zone  10
    Datum  WGS84
    Units  meter
    
    Entity_and_Attribute_Detail_Citation: none


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?

    Peter Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    (831) 427-4709 (FAX)
    pdartnell@usgs.gov


Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify bathymetric features.


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: 2009 (process 1 of 4)
    During the USGS mapping mission, Real Time Kinematic (RTK) GPS data and measurements of vessel motion (heave, pitch, and roll) were combined in a CodaOctopus F190 attitude and position system to produce a high-precision vessel attitude packet. This packet was transmitted to the acquisition software in real time and combined with instantaneous sound-velocity measurements at the transducer head before each ping. The returned samples were projected to the seafloor using a ray-tracing algorithm working with previously measured sound-velocity profiles. Statistical filters were applied to the raw samples that discriminate the seafloor returns (soundings) from other unintended targets in the water column. During the survey, the WGS84 (G1150) reference frame was used for both horizontal and vertical measurements. The soundings were post-processed to NAVD 1988. Finally, the soundings were converted into 2-m-resolution bathymetric-surface-model grids. During the Fugro Pelagos mapping mission that was completed as part of the National Coastal Mapping Program of USACE, the Leica ALS60 topographic-lidar and the SHOALS-1000T bathymetric-lidar systems were mounted on an aircraft that flew survey lines at an altitude of 300 to 400 m (bathymetry) and 300 to 1,200 m (topography), at speeds of between 135 and 185 knots. The ALS60 system collected data at a maximum pulse rate of 200 kHz, and the SHOALS system collected data at 1 kHz. Information on aircraft position, velocity, and acceleration were collected using the Novatel and POS A/V 410 systems (SHOALS) and the onboard GPS/IMU system (ALS60). Aircraft-position data were processed using POSPac software, and the results were combined with the lidar data to produce 3-D positions for each lidar shot. Various commercial and proprietary software packages were used to clean the data, to convert all valid data from ellipsoid to orthometric heights, and to export the data as a series of first-return topography and bathymetry ASCII files.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

    Date: 2012 (process 2 of 4)
    USGS 2-m-resolution bathymetry data from mapping cruise S-8-08-SC were downloaded from USGS archives.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

    Date: 2010 (process 3 of 4)
    Topographic - Bathymetric lidar data were provided to the USGS, PCMSC by USACE.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

    Date: 2012 (process 4 of 4)
    Transform all bathymetry data to common projection, datum, and UTM zone. Merge all 2-m bathymetry data into 2-m-resolution bathymetry grid and clip to the Offshore of Refugio Beach Area, California, map boundary. An illumination having an azimuth of 300 degrees and 45 degrees above the horizon was applied to the 2-m bathymetry grid to create shaded relief imagery.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov

  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?

    Not applicable for raster data.

  2. How accurate are the geographic locations?

    Estimated to be no less than 2 m, owing to total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations.

  3. How accurate are the heights or depths?

    Estimated to be no less than 5 cm, owing to total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations.

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

    Complete

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

    Unspecified


How can someone get a copy of the data set?

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

Access_Constraints: None
Use_Constraints:
This information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.


Who wrote the metadata?

Dates:
Last modified: 28-Nov-2012
Last Reviewed: 28-Nov-2012
Metadata author:
Peter Dartnell
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Physical Scientist
400 Natural Bridges Dr.
Santa Cruz, CA 95060-5792
USA

(831) 460-7415 (voice)
(831) 427-4709 (FAX)
pdartnell@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)


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