Bathymetry Hillshade--Offshore of Ventura, California

Frequently-anticipated questions:

• What does this data set describe?
  1. How should 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 should this data set be cited?

   Kvitek, Rikk G. , Dartnell, Peter, Phillips, Eleyne L. , and Cochrane, Guy R. , 2013, Bathymetry Hillshade--Offshore of Ventura, 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. , Kvitek, Rikk G. , Greene, H. Gary , Krigsman, Lisa M. , Endris, Charles A. , Seitz, Gordon G. , Gutierrez, Carlos I. , Sliter, Ray W. , Erdey, Mercedes D. , Wong, Florence L. , Yoklavich, Mary M. , Draut, Amy E. , Hart, Patrick E. , and Cochran, Susan A. , 2013, California State Waters Map Series--Offshore of Ventura, California: Scientific Investigations Map SIM 3254, U.S. Geological Survey, Reston, VA.

   Online Links:

   • <https://pubs.usgs.gov/sim/3254/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -119.44

   East_Bounding_Coordinate: -119.25

   North_Bounding_Coordinate: 34.38

   South_Bounding_Coordinate: 34.22

3. What does it look like?

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

   Beginning_Date: 2006

   Ending_Date: 2010

   Currentness_Reference: ground condition

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: 11

      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996

      Longitude_of_Central_Meridian: -117.00000

      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 2006 - 2010 bathymetry data was originally archived as an ESRI grid with the following attributes:

   Cell size = 2.0
   Number of rows = 8955
   Number of columns = 8955
   
   Data type = floating point
   
   Boundary
   Xmin = 274890.00
   Xmax = 292800.00
   Ymin = 3788680.00
   Ymax = 3806590.00
   
   Statistics
   Minimum value = -42.84
   Maximum value = -1.99
   Mean = -21.61
   Standard deviation = 7.29
   
   Coordinate system description
   Projection  UTM
   Zone  11
   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)
   • Rikk G. Kvitek
   • Peter Dartnell
   • Eleyne L. Phillips
   • Guy R. Cochrane

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: 2010 (process 1 of 3)

   The bathymetry and shaded-relief maps of the Offshore of Ventura map area in southern California were generated from data collected by California State University, Monterey Bay, Seafloor Mapping Lab (CSUMB) and by the U.S. Geological Survey (USGS). All these mapping missions combined to collect bathymetry from about the 10-m isobath to beyond the 3-nautical-mile limit of California's State Waters. During the CSUMB mapping missions, an Applanix position and motion compensation system (POS/MV) was used to accurately position the vessel during data collection, and it also accounted for vessel motion such as heave, pitch, and roll (position accuracy, +/-2 m; pitch, roll, and heading accuracy, +/-.02 degrees; heave accuracy, +/-5 percent, or 5 cm). NavCom 2050 GPS receiver (CNAV) data were used to account for tidal-cycle fluctuations, and sound-velocity profiles were collected with an Applied Microsystems (AM) SVPlus sound velocimeter. Soundings were corrected for vessel motion using the Applanix POS/MV data, for variations in water-column sound velocity using the AM SVPlus data, and for variations in water height (tides) using vertical-position data from the CNAV receiver. Final XYZ soundings and bathymetric-surface models were referenced to the World Geodetic System of 1984 (WGS 1984) relative to the North American Vertical Datum of 1988 (NAVD 1988). During the USGS mapping missions, differential GPS data (2006) and GPS with real-time kinematic corrections (2010) were combined with measurements of vessel motion (heave, pitch, and roll) in a CodaOctopus F180 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 that works with previously measured sound-velocity profiles. Statistical filters were applied to the raw samples that discriminate the seafloor returns (soundings) from unintended targets in the water column. The original 2006 soundings were referenced to the WGS 1984 relative to the MLLW (Mean Lower Low Water) tidal datum, but, through postprocessing using National Oceanic and Atmospheric Administration?s (NOAA's) VDatum tool, the soundings were transformed to NAVD 1988. The original 2010 soundings were referenced to the WGS 1984 datum using real-time kinematics GPS and then transformed through postprocessing to the NAVD 1988. Finally, the soundings were converted into 2-m-resolution bathymetric-surface-model grids. In 2009, Fugro Pelagos collected bathymetric- and topographic-lidar data along the Ventura and Santa Barbara County coastlines for the U.S. Army Corps of Engineers Joint Lidar Bathymetry Technical Center of Expertise. Although bathymetric coverage was good northwest and southeast of the map area, the coverage within the Offshore of Ventura map area was very sparse; therefore, these data are not included in this map.

   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: 2009 (process 2 of 3)

   California State University, Monterey Bay, Seafloor Mapping Lab 2-m-resolution bathymetry data (CSMP survey blocks D - F) within this map were downloaded from <http://seafloor.csumb.edu/SFMLwebDATA.htm>

   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 3)

   Merge all bathymetry data into 2-m-resolution bathymetry grid and clip to the Offshore of Ventura map area boundary. To create the shaded-relief imagery, an illumination having an azimuth of 300 degrees and 45 degrees above the horizon was applied to the bathymetry grid.

   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:

Please recognize the U.S. Geological Survey (USGS) and the California State University, Monterey Bay, Seafloor Mapping Lab (CSUMB). USGS-authored or produced data and information are in the public domain. 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 USGS and CSUMB 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: 15-Mar-2013
Last Reviewed: 15-Mar-2013

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)