Identification_Information:
  Citation:
    Citation_Information:
      Originator: National Ocean Service - National Oceanic and Atmospheric Administration
      Originator: U.S. Geological Survey
      Originator: California Department of Fish and Game
      Publication_Date: 200208
      Title: Bathymetric DEM, 200 Meter Resolution (Depth Values in Fathoms)
      Geospatial_Data_Presentation_Form: raster digital data
      Online_Linkage: \\Molib01\GIS_Library\Elevation\Water\DEMs\DFG_Bathymetry_Project\bdem200m_fa
  Description:
    Abstract:
      California coastwide bathymetric Digital Elevation Model (DEM) at 200 meter resolution with depth values in fathoms.  This DEM is a resampled mosaic of smaller, tiled DEMs produced from source data of varying densities.  Offshore coverage is approximately out to the Exclusive Economic Zone (EEZ) boundary.  An small inland buffer of coastal terrestrial values coded to zero is included for cartographic overlap.

      Nearshore depths were produced from NOS Hydrographic Survey data with a tidal datum of mean lower low water (MLLW).  Far offshore areas were produced from U.S. Geological Survey depth contours with no documented tidal datum.

      Please see the provided Bathymetry Project documentation for further information.
    Purpose: Assess depths for the California coast.
    Supplemental_Information:
      -- BEGIN EXCERPTS FROM BATHYMETRY PROJECT DOCUMENTATION -- 

      California Department of Fish and Game
      BATHYMETRY PROJECT      
      Second Edition
      
      This document provides an overall description of the 
      California Department of Fish and Game (DFG) bathymetry 
      development project, including source datasets, processes 
      used, and resulting products.  

      The bathymetry data are not suitable for navigation.
      DFG makes no warranty as to the suitability of the
      bathymetry data, and any project-related datasets, for
      any purpose.

      In addition to this readme file, other documentation files
      (text, XML, etc.) may accompany datasets related to this 
      project.


      ACKNOWLEDGEMENTS

      The bathymetry processing methods and documentation
      were originally developed by the State of California
      Stephen P. Teale Data Center, GIS Solutions Group (Teale)
      under DFG direction.  Key Teale staff involved in the
      project included Andy Richardson and Virginia Wong-Coppin. 


      REVISIONS

      A second edition of the bathymetry data was completed by
      DFG in August 2002. The second edition data were processed
      using ARC/INFO GIS software in a Windows 2000 operating
      system environment and included the following enhancements:
      - Correction or exclusion of over 1700 miscoded and
      suspicious Hydrographic Surveys used in the bathymetry 
      development process.
      - Replacement of older U.S. Geological Survey 7.5-minute 
      terrestrial elevation data with the newer/higher-quality 
      National Elevation Dataset (NED) for use in nearshore 
      bathymetry interpolation.
      - Minor adjustments to some of the ARC/INFO software
      ARC Macro Language (AML) scripts and resolution zone
      boundaries used to process the bathymetry data.


      GEOGRAPHIC AREA 

      Bathymetry was developed to cover most of the 200 nautical
      mile Exclusive Economic Zone (EEZ) off the coast of
      California.  The actual extent of data is slightly beyond 
      this zone in some areas to account for the 100 kilometer
      tiles used to process source data (some tiles extend beyond
      the EEZ boundary by as much as almost a tile width, or less
      than 100 KM).  To the east, the coverage includes many major
      inlets along the coast.  The tiles also extend north and
      south of California by less than 1 tile height.


      RESULTING PRODUCTS

      Initially a single coastwide Digital Elevation Model (DEM)
      was evisioned to be the product resulting from this project.
      Upon commencing the project it became evident that due to
      the nature of the source data multiple datasets were
      appropriate. These include:

      1.  Coastwide 25, 50, 100, and 200 meter zonal DEMs
      2.  5 meter zonal DEMs for localities supported by 
      high-density source data
      3.  Tiled 5, 25, 50, 100, and 200 meter zonal DEMs
      4.  Tiled 25 meter base DEMs

      The coastwide 25-200 meter zonal DEMs are based on the fact
      that there is a wide variation in the density of the source
      data.  Where data were dense, a 25 meter zonal DEM was
      generated.  Where data were sparse, a 200 meter zonal DEM
      was generated.  The 50 and 100 meter zonal DEMs represent
      intermediate densities.  Though "coastwide", data in these
      DEMs do not overlap, however together they cover the entire
      study area.  These 25, 50, 100, and 200 meter "zones" were
      defined by plotting the source data on paper, visually
      identifying and hand drafting zone boundaries based on data
      density, then capturing the boundaries in digital format.

      The 5 meter zonal DEMs correspond to areas where source data 
      are particularly dense.  These areas were identified by
      visually scanning the source data on-screen, and "heads up"
      digitizing the boundaries.  These DEMs differ from the 25-200
      meter zonal DEMs in that they were processed using different
      tolerances and that they were not merged into a single
      coastwide zonal DEM (due to resolution / storage constraints).
      These DEMs are available named by geographic localities or as
      tiled data.

      The tiled 5-200 meter zonal DEMs are simply the coastwide
      zonal DEMs (or individual 5 meter zonal DEMs) clipped to a 
      7500 meter buffered tile extent and stored in the tile
      directory.  This makes it easy for a user to find DEMs of
      all available resolutions for a single tile.  Tile directories
      store only those resolutions that cover the tile.

      The tiled 25 meter base DEMs are intermediate products used
      to generate the 25-200 meter zonal DEMs.  These have proven
      useful as a source for generating contours and depth range
      polygons.  They are also useful for visualizing and analyzing
      small geographic areas, though the user must understand that
      the source data do not necessarily support 25 meter resolution.
      These DEMs are tile-wide in extent, and are available clipped
      to the tile boundary (dembase) and buffered 7500 meters beyond
      the tile (dembaseb).

      An available georeferenced map image (bathy_map.jpg with 
      bathy_map.jgw world file) shows spatial distribution, tile
      numbers, and resolution zones of the DEM data.


      SOURCE DATA

      Four sources of depth/elevation data were used to create the
      bathymetric DEMs:

      1. Hydrographic Survey Data version 4.0, National Ocean
      Service (NOS), National Oceanic and Atmospheric
      Administration, U.S. Department of Commerce.
      Dataset name = hydsura (ESRI coverage format).
      2. U.S. Geological Survey bathymetric contours for the 
      California EEZ - 100m contours from 200m to maximum depth.
      Dataset name = eezbata (ESRI coverage format).
      3. 30 meter terrestrial DEM based on the National Elevation
      Dataset (NED), U.S. Geological Survey, U.S. Department of
      the Interior.  Dataset name = dema (ESRI grid format).
      4. 1:24,000-scale State of California Coastline, State
      Lands Commission, State of California.  Dataset name =
      rawclipa (ESRI coverage format).

      The NOS Hydrographic Surveys were the primary nearshore
      depth data used to create the bathymetric DEMs.  These
      data represent multiple historical ship transects and were
      imported to ARC/INFO as a set of over 6 million points.
      Sampling density is quite variable, as close as a few
      meters in inland bays and as far apart as hundreds or
      thousands of meters away from the coast.  The Hydrographic
      Surveys were processed as-is and not filtered to model a
      particular range of dates.

      The U.S. Geological Survey bathymetric contours were
      provided by the U. S. Geological Survey Coastal and Marine
      Geology Team.  The original dataset known as "eezbatcall"
      was reprojected by DFG to the California (Teale) Albers
      projection.  The coverage provided contours from 200 meters
      to maximum depth for the California EEZ area.  The contours
      were digitized from various small-scale (approximately
      1:1,000,000) U.S. Geological Survey maps.

      The 30 meter terrestrial DEM was used to allow continuous
      gridding along the coast.  Though there is no land area
      included in the resulting products, the bathymetry gridding
      process requires sampling data beyond the edge of the
      resulting grid to smoothly interpolate depth/elevation
      along the edge.  The NED terrestrial DEM data were
      distributed by the U.S. Geological Survey then processed
      and re-distributed by Teale.

      The 1:24,000 coastline was used to define land and water
      areas and as source depth points of "0".  This results in
      a well-defined coastline in the bathymetric DEMs.  The
      original State Lands Commission coastline coverage was
      modified by Teale for project purposes.


      PROCESSING DATA

      In addition to the source depth/elevation data, a number of
      datasets were used to control processing.  These include:

      1.  TILE100KM
      2.  RES_ZONES
      3.  RAWCLIPA
      4.  M5_ZONES

      TILE100KM is a set of 100 kilometer square (10,000 square
      kilometers) tiles used to split the entire EEZ into 75
      managable processing areas.  Many of the resulting datasets
      are also stored by these tiles.

      RES_ZONES are zones corresponding to the density of source
      data that were used to determine the resolution of the
      resulting zonal DEMs (5, 25, 50, 100, and 200 meters).

      RAWCLIPA contains a set of polygons that define which areas
      are water and which areas are land.  This dataset serves two
      functions in the gridding process.  Coastlines are
      extracted, converted to a set of points with a depth value
      of "0", merged with the Hydrographic Surveys, U.S. Geological
      Survey bathymetric contours, terrestrial DEMs, and gridded. 
      When gridding is complete, land polygons are pulled from this 
      dataset and used to blank out the resulting DEM.

      M5_ZONES are areas where the Hydrographic Surveys support 5
      meter gridding.  The final products include a single 5 meter
      zonal DEM for each polygon in this dataset.


      PROCESSING METHODOLOGY

      The primary engine behind the gridding process is the
      ARC/INFO TOPOGRID tool.  TOPOGRID uses an iterative finite
      difference interpolation technique that is essentially a
      discretized thin plate spline technology.  It is based upon
      the ANUDEM program developed my Michael Hutchinson.  The
      online help for TOPOGRID contains the following references:

      Hutchinson, M.F. 1988.  Calculation of hydrologically
      sound digital elevation models.  Third International
      Symposium on Spatial Data Handling, Sydney.  Columbus,
      Ohio: International Geographic Union.

      Hutchinson, M.F. 1989.  A new procedure for gridding
      elevation and stream line data with automatic removal of
      spurious pits.  Journal of Hydrology: 106, 211-232.

      Hutchinson, M.F. and Dowling, T.I. 1991.  A continental
      hydrological assessment of a new grid-based digital
      elevation model of Australia.  Hydrological Processes 5:
      45-58.

      Hutchinson, M.F. 1993.  Development of a continent-wide
      DEM with applications to terrain and climate analysis.
      In: M.F. Goodchild et al (eds), Environmental Modeling
      with GIS.  New York, Oxford University Press: 392-399.

      Wahba, G.  1990.  Spline models for Observational data.
      CBMS-NSF Regional Conference Series in Applied
      Mathematics, Philadelphia: Soc. Ind. Appl. Maths.

      The following TOPOGRID parameters were used to create the
      25-200 meter DEMs:
      DATATYPE SPOT
      ENFORCE OFF
      ITERATIONS 30
      TOLERANCES 2.5 1.5 10
      XYZLIMITS %LIMITS% (%LIMITS% = bounding box of buffered 
      tile)

      The following TOPOGRID parameters were used to create the
      5 meter DEMs:
      BOUNDARY XXZONE  (XXZONE is the 5 meter zone polygon)
      DATATYPE SPOT
      ENFORCE OFF
      ITERATIONS 30
      TOLERANCES 2.5 1.5 2.5
      XYZLIMITS %LIMITS%  (%LIMITS% is 50 meters beyond the 5
      meter zone polygon bounding box)

      The processing logic applied to each of the 75 tiles to
      create the 25-200 meter DEMs was:
      - Receive the tile number to process
      - Create a results directory corresponding to the tile 
      number
      - Extract the tile from TILE100KM
      - Buffer the tile 10 KM
      - Using the buffered tile, clip out:
      - RES_ZONES
      - RAWCLIPA (land water polygons)
      - Hydrographic Surveys
      - Coastlines (from RAWCLIPA)
      - Convert to points
      - Terrestrial DEM (if tile covers land area)
      - Convert to points
      - U. S. Geological Survey bathymetric contours (if tile 
      covers 200 meter zone)
      - Merge all point coverages
      - Run TOPOGRID to create 25 meter DEM covering buffered tile 
      area
      - Blank out land areas
      - Clip to 7500 meters beyond tile boundary; store in tile 
      directory
      - Clip to tile boundary; store in tile directory
      - For each resolution zone covered by the tile:
      - Clip out area from buffered DEM
      - Resample to appropriate resolution for zone (using bilinear
      interpolation)
      - Blank out land areas
      - Store in tile directory

      The process used to create the 5 meter DEMs is:
      - For each polygon in M5_ZONES:
      - Create a coverage containing a single rectangle polygon
      50 meters (10 5 meter cells) larger than the zone 
      polygon
      - Using the rectangle, clip out:
      - RAWCLIPA (land water polygons)
      - Hydrographic Surveys
      - Coastlines (from RAWCLIPA)
      - Convert to points
      - Terrestrial DEM (if tile covers land area)
      - Convert to points
      - Merge the resulting point coverages
      - Run TOPOGRID to create 5 meter DEM covering the 
      rectangle
      - Blank out land areas
      - Clip to extent of the zone polygon

      After the original tiled 25 meter base DEMs were created
      by Teale, shaded reliefs were generated and visually 
      inspected.  Miscoded points that resulted in spurious pits
      or spikes were identified and coded as such.  After all 
      errors were corrected for a tile, the DEMs for the tile 
      were re-created and re-inspected.

      DATA QUALITY ASSESSMENT

      The following are subjective comments regarding the data.

      Because the bathymetry data were generated from a variety 
      of sources at varying scales, overall accuracy is difficult
      to assess.  The data have not been thoroughly reviewed.
      Depth values should be corroborated with other sources.

      Some "artifacts" are present in the data, and may be 
      especially noticeable along resolution zone and tile
      boundaries where differing data sources may not have
      provided a smooth interpolation transition.  Additional
      errors may be present.

      Source Hydrographic Survey data originated from many
      historical surveys and thus do not necessarily represent
      current hydrologic conditions.  For accuracy assessments
      of Hydrographic Survey data, please reference the
      documentation for that product.

      DEM depth values are of particular questionable quality
      in the following areas.  Other problem areas may exist.

      - Nearshore areas north of Mack Pt. (southern Oregon).
      Source terrestrial elevation data was missing for 
      this area but depth values were still interpolated
      to the shoreline.

      - Nearshore, Gulf of the Farallones area, south of Stormy
      Stack and north of Muir Beach out to about -25 meters 
      depth.  Source depth data was missing for this area but 
      depth values were still interpolated to the shoreline.

      - Nearshore areas south of the California border
      out to -200 meters depth.  Source depth and terrestrial
      elevation data were missing for this area but depth 
      values were still interpolated to the shoreline.

      - Any depth values outside of the gridding resolution
      zones.  Cross-reference the "tile100km" and "res_zones"
      coverages used in data processing to determine areas
      within tiled DEMs that are outside the resolution zones.
      The georeferenced map image (bathy_map.jpg with 
      bathy_map.jgw world file) can also be used for this
      purpose.

      - San Diego Bay.  Source data were missing for portions
      of the bay but depth values were still interpolated.

      Readme Version 2002.08.23

      -- END EXCERPTS FROM BATHYMETRY PROJECT DOCUMENTATION --
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -129.267938
      East_Bounding_Coordinate: -116.582361
      North_Bounding_Coordinate: 42.406405
      South_Bounding_Coordinate: 31.958108
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: elevation
      Theme_Keyword: geoscientificInformation
      Theme_Keyword: oceans
    Theme:
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: bathymetry
    Place:
      Place_Keyword_Thesaurus: none
      Place_Keyword: California
  Access_Constraints: none
  Use_Constraints: The bathymetry data are not suitable for navigation.  DFG makes no warranty as to the suitability of the data for any purpose.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Will Patterson
        Contact_Organization: California Department of Fish and Game
      Contact_Electronic_Mail_Address: wpatters@dfg.ca.gov
  Native_Data_Set_Environment: Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4; ESRI ArcCatalog 8.3.0.800
Data_Quality_Information:
  Completeness_Report: Please see the provided Bathymetry Project documentation.
  Lineage:
    Process_Step:
      Process_Description: Converted to NAD83 (ArcInfo Workstation 9.1 PROJECTGRID command using bilinear interpolation), metadata edited.
      Process_Date: 200608
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Will Patterson
            Contact_Organization: California Department of Fish and Game
          Contact_Electronic_Mail_Address: geodata@dfg.ca.gov
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Grid Cell
    Row_Count: 5635
    Column_Count: 5248
    Vertical_Count: 1
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Map_Projection:
        Map_Projection_Name: Albers Conical Equal Area
        Albers_Conical_Equal_Area:
          Standard_Parallel: 34.000000
          Standard_Parallel: 40.500000
          Longitude_of_Central_Meridian: -120.000000
          Latitude_of_Projection_Origin: 0.000000
          False_Easting: 0.000000
          False_Northing: -4000000.000000
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 200.000000
          Ordinate_Resolution: 200.000000
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137.000000
      Denominator_of_Flattening_Ratio: 298.257222
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: bdem200m_m
    Attribute:
      Attribute_Label: ObjectID
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated.
    Attribute:
      Attribute_Label: Value
    Attribute:
      Attribute_Label: Count
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: GIS Service Center
        Contact_Organization: California Department of Fish and Game
      Contact_Electronic_Mail_Address: geodata@dfg.ca.gov
  Resource_Description: Downloadable Data
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Transfer_Size: 20.093
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Marine Region GIS
        Contact_Organization: California Department of Fish and Game
      Contact_Electronic_Mail_Address: MR_GIS@dfg.ca.gov
Metadata_Reference_Information:
  Metadata_Date: 20060818
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: California Department of Fish and Game
        Contact_Person: GIS Service Center
      Contact_Address:
      Contact_Electronic_Mail_Address: geodata@dfg.ca.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Extensions:
    Online_Linkage: http://www.esri.com/metadata/esriprof80.html
    Profile_Name: ESRI Metadata Profile
