Metadata:
  Identification_Information:
    Citation:
      Citation_Information:
        Originator: Schweitzer, Peter N.
        Publication_Date: 1995
        Title: Monthly average polar sea-ice concentration
        Edition: 1
        Geospatial_Data_Presentation_Form: remote-sensing image
        Series_Information:
          Series_Name: U.S. Geological Survey Digital Data Series
          Issue_Identification: DDS-27
        Publication_Information:
          Publication_Place: Reston, Virginia
          Publisher: U.S. Geological Survey
        Online_Linkage: <http://geochange.er.usgs.gov/pub/sea_ice/>

    Description:
      Abstract:
        This data set represents the results of calculations carried
        out on sea-ice-concentration data from the SMMR and SSM/I
        instruments.  The original data were obtained from the
        National Snow and Ice Data Center (NSIDC). The data set also
        contains the source code of the programs that made the
        calculations.  The objective was to derive monthly averages
        for the whole 13.25-year series (1978-1991) and to derive a
        composite series of monthly averages representing the
        variation of an average year.  The resulting file set contains
        monthly images for each of the polar regions for each year,
        yielding 160 files for each pole, and composite monthly
        averages in which the years are combined, yielding 12 more
        files.  Averaging the images in this way tends to reduce the
        number of grid cells that lack valid data; the composite
        averages are designed to suppress interannual variability.

        Also included in the data set are programs that can retrieve
        seasonal ice-concentration profiles at user-specified
        locations.  These nongraphical data retrieval programs are
        provided in  versions for UNIX, extended DOS, and Macintosh
        computers.  Graphical browse utilities are included for the
        same computing platforms but require more sophisticated
        display systems.

      Purpose:
        The purpose of this data set is to provide paleoclimate
        researchers with a tool for estimating the average seasonal
        variation in sea-ice concentration in the modern polar oceans
        and for estimating the modern monthly sea-ice concentration at
        any given polar oceanic location.  It is expected that these
        data will be compared with paleoclimate data derived from
        geological proxy measures such as faunal census analyses and
        stable-isotope analyses. The results can then be used to
        constrain general circulation models of climate change.

      Supplemental_Information:
        The data contained in this data set are derived from the
        Scanning Multichannel Microwave Radiometer (SMMR) and Special
        Sensor Microwave/ Imager (SSM/I) data produced by the National
        Snow and Ice Data Center (NSIDC) at the University of Colorado
        in cooperation with the U.S. National Aeronautics and Space
        Administration (NASA) and the U.S. National Oceanic and
        Atmospheric Administration (NOAA).  The basic data come from
        satellites of the U.S. Air Force Defense Meteorological
        Satellite Program.  NSIDC distributes three collections of sea-
        ice-concentration grids on CD-ROM: data from the Nimbus-7 SMMR
        (October 25, 1978 through August 20, 1987) are provided on
        volume 7 of the SMMR Polar Data series (NASA, 1992); data from
        the SSM/I are provided on two separate volumes, covering the
        periods from July 9 of 1987 to December 31 of 1989, and from
        January 1 of 1990 through December 31 of 1991, respectively.
        The NASATEAM data from revision 2 of the SSM/I CD-ROM's were
        used to create the present data set.  SMMR images were
        collected every 2 to 3 days, whereas SSM/I data are provided
        in daily ice-concentration grids.  Apart from a number of
        small gaps (5 or fewer days) in the record, the only long
        period for which no data are available is December 3 of 1987
        through January 12 of 1988, inclusive.

        As ancillary data, the ETOPO5 global gridded elevation and
        bathymetry data (Edwards, 1989) were interpolated to the
        resolution of the NSIDC data; the interpolated topographic
        data are included.

        The images are provided in three formats: Hierarchical Data
        Format (HDF), a flexible scientific data format developed at
        the National Center for Supercomputing Applications; Graphics
        Interchange Format (GIF); and Macintosh PICT format.  The ice-
        concentration grids are distributed by NSIDC in HDF format.

    Time_Period_of_Content:
      Time_Period_Information:
        Range_of_Dates/Times:
          Beginning_Date: 19781025
          Ending_Date: 19911231
      Currentness_Reference:
        SMMR aboard Nimbus-7 satellite became fully operational on
        781025; that instrument was replaced but the observations were
        continued by the SSM/I aboard DMSP F8 satellite.

    Status:
      Progress: Complete
      Maintenance_and_Update_Frequency: Irregular

    Spatial_Domain:
      Bounding_Coordinates:
        West_Bounding_Coordinate: -180.0
        East_Bounding_Coordinate: 180.0
        North_Bounding_Coordinate: 90.0
        South_Bounding_Coordinate: -90.0
      Data_Set_G-Polygon:
        Data_Set_G-Polygon_Outer_G-Ring:
          G-Ring: 168.35,30.98,135.00,39.43,102.34,31.37,45.00,56.35,-9.97,34.35,-45.00,43.28,-80.74,33.92,-135.00,55.50
      Data_Set_G-Polygon:
        Data_Set_G-Polygon_Outer_G-Ring:
          G-Ring: -42.24,-39.23,0.00,-51.32,42.24,-39.23,90.00,-54.66,135.00,-41.45,180.00,-54.66,-135.00,-41.45,-90.00,-54.66
    Keywords:
      Theme:
        Theme_Keyword_Thesaurus: None
        Theme_Keyword: Oceanography
        Theme_Keyword: Sea-Ice Concentration
      Place:
        Place_Keyword_Thesaurus: None
        Place_Keyword: Arctic Ocean
        Place_Keyword: Southern Ocean
      Temporal:
        Temporal_Keyword_Thesaurus: None
        Temporal_Keyword: Present

    Access_Constraints: none
    Use_Constraints: none

    Point_of_Contact:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Peter N. Schweitzer
          Contact_Organization: Global Change and Climate History Program
        Contact_Address:
          Address_Type: mailing address
          Address:
            Mail Stop 918 National Center
            U.S. Geological Survey
            12201 Sunrise Valley Drive
          City: Reston
          State_or_Province: VA
          Postal_Code: 20192
          Country: USA
        Contact_Voice_Telephone: (703) 648-6533
        Contact_Facsimile_Telephone: (703) 648-6560
        Contact_Electronic_Mail_Address: pschweitzer@usgs.gov

    Browse_Graphic:
      Browse_Graphic_File_Name: <http://geochange.er.usgs.gov/pub/sea_ice/Derived/images/gif/north/02n.gif>
      Browse_Graphic_File_Description:
        Average February Northern Hemisphere sea-ice concentration
        plotted on a polar stereographic projection of the North Pole
      Browse_Graphic_File_Type: GIF

    Browse_Graphic:
      Browse_Graphic_File_Name: <http://geochange.er.usgs.gov/pub/sea_ice/Derived/images/gif/south/02s.gif>
      Browse_Graphic_File_Description:
        Average February Southern Hemisphere sea-ice concentration
        plotted on a polar stereographic projection of the South Pole
      Browse_Graphic_File_Type: GIF

    Browse_Graphic:
      Browse_Graphic_File_Name: <http://geochange.er.usgs.gov/pub/sea_ice/Derived/images/pict/north/02n.pict>
      Browse_Graphic_File_Description:
        Average February Northern Hemisphere sea-ice concentration
        plotted on a polar stereographic projection of the North Pole
      Browse_Graphic_File_Type: PICT2

    Browse_Graphic:
      Browse_Graphic_File_Name: <http://geochange.er.usgs.gov/pub/sea_ice/Derived/images/pict/south/02s.pict>
      Browse_Graphic_File_Description:
        Average February Southern Hemisphere sea-ice concentration
        plotted on a polar stereographic projection of the South Pole
      Browse_Graphic_File_Type: PICT2

    Native_Data_Set_Environment:
      This data set is provided on a single CD-ROM in ISO 9660 format
      with Macintosh-compatible HFS directory information as well.  The
      data set was developed on a Data General AViiON computer system
      running DG/UX version 5.4R3.10 (UNIX); additional software
      products provided on the CD-ROM were developed on a Macintosh IIci
      and on an IBM-compatible personal computer made by ZEOS, Inc.,
      running an Intel 80486 DX microprocessor.

    Cross_Reference:
      Citation_Information:
        Originator: Peter N. Schweitzer
        Publication_Date: 1993
        Title: Modern Average Global Sea-Surface Temperature
        Geospatial_Data_Presentation_Form: remote-sensing image
        Series_Information:
          Series_Name: U.S. Geological Survey Digital Data Series
          Issue_Identification: DDS-10
        Other_Citation_Details: Library of Congress Cataloging-in-Publication Number 93-9075
        Online_Linkage: <ftp://geochange.er.usgs.gov/pub/magsst/cdrom>
        Online_Linkage: <http://geochange.er.usgs.gov/pub/magsst/magsst.html>

  Data_Quality_Information:
    Attribute_Accuracy:
      Attribute_Accuracy_Report:
        Calculation of sea-ice-concentration values from brightness
        temperatures is described extensively in the user's guides of
        the source data products and in the NASA publication dealing
        with the SMMR data.

    Logical_Consistency_Report:
      Included in the data set are the UNIX shell scripts and makefiles
      that were used to derive the averages and create the tables and
      images.  Source code is provided for all programs written by the
      author.

    Completeness_Report:
      Included in the data set is a table enumerating the days for which
      sea-ice-concentration data were available in the source material.
      In general, images were available every 2 days during the time
      period from 781025 through 870709, when the SMMR was used, and
      images were available every day during the period 870709 through
      911231, when the SSM/I was used.  A large gap (871202 through
      880113) occurred when the SSM/I became temporarily inoperative.
      Other gaps in the SSM/I record were not longer than five
      consecutive days.

    Positional_Accuracy:
      Horizontal_Positional_Accuracy:
        Horizontal_Positional_Accuracy_Report:
          The grids provided in the source data (supplied by NSIDC)
          are described in the user's guides of the relevant
          products, and the positional accuracy of the pixels is
          dealt with both in the user's guides and in the NASA
          report on the SMMR data.

    Lineage:
      Source_Information:
        Source_Citation:
          Citation_Information:
            Originator: NASA
            Publication_Date: 1992
            Title:
              Radiances on a North Polar Stereographic Grid
              4/1/ 87 - 8/20/87 and Arctic and Antarctic Sea Ice
              Concentrations 10/25/78 - 8/20/87 volume 7 of
              Nimbus-7 Scanning Multichannel Microwave
              Radiometer (SMMR) Polar Data
            Geospatial_Data_Presentation_Form: remote-sensing image
            Series_Information:
              Series_Name: Goddard Space Flight Center SMMR Polar Data
              Issue_Identification: volume 7
            Other_Citation_Details:
              The volume also contains brightness temperature data
              from 870401 through 870820.  The CD-ROM is labelled
              USA_NASA_971_SMR_0007.  The data are distributed by
              NSIDC Distributed Active Archive Center, Cooperative
              Institute for Research in Environmental Sciences
              (CIRES), University of Colorado, Boulder, CO 80309-0049.
        Source_Citation_Abbreviation: SMMR CD-ROM from NSIDC
        Type_of_Source_Media: CD-ROM
        Source_Time_Period_of_Content:
          Time_Period_Information:
            Range_of_Dates/Times:
              Beginning_Date: 19781025
              Ending_Date: 19870820
          Source_Currentness_Reference:
            National Snow and Ice Data Center, 1994, Nimbus-7 SMMR
            polar radiances and Arctic and Antarctic sea ice
            concentrations on CD-ROM user's guide, version 3:
            Boulder, Colorado, National Snow and Ice Data Center, 23 p.
        Source_Contribution:
          Monthly average sea-ice-concentration files in the present
          data set for the period 781025 through 870820 were derived
          from these Nimbus-7 SMMR ice-concentration data.

      Source_Information:
        Source_Citation:
          Citation_Information:
            Originator: NSIDC
            Publication_Date: 1992
            Title:
              DMSP SSM/I ice concentration grids for the polar
              regions
            Geospatial_Data_Presentation_Form: remote-sensing image
            Series_Information:
              Series_Name:
                DMSP SSM/I brightness temperature and sea-ice
                concentration grids for the polar regions on CD-ROM
              Issue_Identification: volume 1, revision 2
            Other_Citation_Details:
              The data are distributed by NSIDC Distributed Active
              Archive Center, Cooperative Institute for Research in
              Environmental Sciences (CIRES), University of
              Colorado, Boulder, CO 80309-0049.
        Source_Citation_Abbreviation: DMSP/SSMI ICE Grids volume 1
        Type_of_Source_Media: CD-ROM
        Source_Time_Period_of_Content:
          Time_Period_Information:
            Range_of_Dates/Times:
              Beginning_Date: 19870709
              Ending_Date: 19891231
          Source_Currentness_Reference:
            National Snow and Ice Data Center, 1992, DMSP SSM/I
            brightness temperature and sea ice concentration grids
            for the polar regions on CD-ROM, User's guide:
            National Snow and Ice Data Center Special Report 1, [300 p].
        Source_Contribution:
          Monthly average sea-ice-concentration files in the present
          data set for the period 19870709 through 19891231 were
          derived from these DMSP F8 SSM/I ice-concentration data.

      Source_Information:
        Source_Citation:
          Citation_Information:
            Originator: NSIDC
            Publication_Date: 1993
            Title:
              DMSP SSM/I ice concentration grids for the polar
              regions
            Geospatial_Data_Presentation_Form: remote-sensing image
            Series_Information:
              Series_Name:
                DMSP SSM/I brightness temperature and sea-ice
                concentration grids for the polar regions on CD-ROM
              Issue_Identification: volume 2, revision 2.
            Other_Citation_Details:
              The data are distributed by NSIDC Distributed Active
              Archive Center, Cooperative Institute for Research in
              Environmental Sciences (CIRES), University of
              Colorado, Boulder, CO 80309-0049.
        Source_Citation_Abbreviation: DMSP/SSMI ICE Grids volume 2
        Type_of_Source_Media: CD-ROM
        Source_Time_Period_of_Content:
          Time_Period_Information:
            Range_of_Dates/Times:
              Beginning_Date: 19900101
              Ending_Date: 19911231
          Source_Currentness_Reference:
            National Snow and Ice Data Center, 1992, DMSP SSM/I
            brightness temperature and sea ice concentration grids
            for the polar regions on CD-ROM, User's guide:
            National Snow and Ice Data Center Special Report 1, [300 p].
        Source_Contribution:
          Monthly average sea-ice-concentration files in the present
          data set for the period 19900101 through 19911231 were
          derived from these DMSP F8 SSM/I ice-concentration data.

      Source_Information:
        Source_Citation:
          Citation_Information:
            Originator: Edwards, Margaret H.
            Publication_Date: 1989
            Title:
              Global gridded elevation and bathymetry (ETOPO5):
              Digital raster data on a 5-minute geographic
              (lat/long) 2160x4320 (centroid-registered) grid
            Geospatial_Data_Presentation_Form: remote-sensing image
            Publication_Information:
              Publication_Place: Boulder, Colorado
              Publisher:
                U.S. National Oceanic and Atmospheric
                Administration, National Geophysical Data
                Center
        Source_Citation_Abbreviation: ETOPO5
        Type_of_Source_Media: CD-ROM
        Source_Time_Period_of_Content:
          Time_Period_Information:
            Range_of_Dates/Times:
              Beginning_Date: 1950
              Ending_Date: 1989
          Source_Currentness_Reference:
            The data set was published in 1989.  Documentation
            provided by NGDC indicates the data were derived from
            sources produced during the period 1950 through 1980.
        Source_Contribution:
          Elevation and bathymetry used in the graphical data
          retrieval programs of DDS-27 were derived from ETOPO5.

      Process_Step:
        Process_Description:
          Calculate monthly averages and composite monthly averages.

          The Bourne shell script do_avgs describes the manner in
          which the program average was used to calculate the
          monthly and composite monthly average sea-ice
          concentration files.  The program average is given a list
          of sea-ice-concentration data files in HDF format.  For
          each grid cell in the images, it calculates the arithmetic
          average of the corresponding cell in the input files and
          writes the average image into a new file.  This program is
          run once for each month of each year represented in the
          original data to yield monthly averages.  Then the
          composite monthly averages are calculated using the
          monthly averages for each year.
        Source_Used_Citation_Abbreviation: DMSP/SSMI Ice Grids volume 1
        Source_Used_Citation_Abbreviation: DMSP/SSMI Ice Grids volume 2
        Process_Date: 1994

      Process_Step:
        Process_Description:
          Create GIF and PICT images of monthly and composite
          monthly averages.

          The Bourne shell script do_imgs converts the monthly
          average and composite monthly average files into GIF and
          PICT images.  This script uses two programs from the
          freely available PbmPlus toolkit developed by Jeff
          Poskanzer.
        Process_Date: 1994

      Process_Step:
        Process_Description:
          Regrid ETOPO5 elevation and bathymetry data to fit sea-ice
          concentration grid.

          The ETOPO5 global gridded elevation and bathymetry data
          set describes world topography on a grid whose cells
          measure 5 minutes of latitude by 5 minutes of longitude.
          Since the ice-concentration data are given in a polar
          stereographic projection, the elevation of cells in the
          ice-concentration grid must be determined by appropriately
          sampling or interpolating the ETOPO5 data.  Because the
          ETOPO5 grid is finer than the ice-concentration grid, a
          sampling algorithm was combined with a spatial averaging
          scheme to derive the desired elevation data. The program
          that implements this algorithm is called topo.c; its
          strategy is to find the ice grid cell coordinates of the
          center of each ETOPO5 cell and to calculate the average
          depth of all of the ETOPO5 cells that fall within an ice
          grid cell.  The results are two 16-bit images with big-
          endian byte ordering in which each signed 16-bit word
          describes the average depth or elevation in meters (sea
          level is zero) of a cell in the ice-concentration grid.

          Along with the 16-bit depth data files, displayable images
          are created using depthppm.c in portable pixmap format,
          and from that intermediate stage, GIF and PICT images are
          created using the PbmPlus toolkit.  Depthppm reduces the
          complexity of the depth data by assigning one color to a
          range of depths.  The relationship between depth ranges
          and colors is given in the source-code file depthppm.c.

          The Bourne shell script do_topo carries out these operations.
        Source_Used_Citation_Abbreviation: ETOPO5
        Process_Date: 1994

      Process_Step:
        Process_Description:
          Create 2-degree by 2-degree gridded ASCII data files.

          One of the principal derivative products of this data set
          is a set of ice-concentration grids in which the grid cell
          size and position match those produced by the USGS PRISM
          project for its reconstruction of the climate of the
          Pliocene, a warm interval about 3 million years before
          present.  These grids are tab-delimited ASCII files
          suitable for use in spreadsheet programs; each cell of the
          spreadsheet represents the ice-concentration value of one
          grid cell measuring 2 degrees latitude by 2 degrees
          longitude.  This calculation is carried out by the Bourne
          shell script do_tabs.

          The procedure is to use a list of the geographic
          coordinates of the grid cell centers as the request file
          for the program u_rtrv.  The result is a table where each
          row is a grid cell, and columns 3 through 14 represent the
          ice-concentration profile for each grid cell (columns 1
          and 2 reiterate the grid cell coordinates).

          The grid cell centers are given in the files grid_n.2x2
          and grid_s.2x2 for the Northern and Southern Hemispheres,
          respectively.  The output of u_rtrv is stored in the files
          arctic.2x2 and antarctic.2x2.

          By using the UNIX cut command, the columns themselves were
          isolated in separate files, and the program table.c was
          used to rearrange each column into a tab-delimited ASCII
          table suitable for entry into a spreadsheet.
        Process_Date: 1994

  Spatial_Data_Organization_Information:
    Direct_Spatial_Reference_Method: Raster

    Raster_Object_Information:
      Raster_Object_Type: Pixel
      Row_Count: 304
      Column_Count: 448

    Raster_Object_Information:
      Raster_Object_Type: Pixel
      Row_Count: 316
      Column_Count: 332

  Spatial_Reference_Information:
    Horizontal_Coordinate_System_Definition:
      Planar:
        Map_Projection:
          Map_Projection_Name: Polar Stereographic
          Polar_Stereographic:
            Straight-Vertical_Longitude_from_Pole: 135.0
            Standard_Parallel: 70.0
            False_Easting: 0.0
            False_Northing: 0.0
        Planar_Coordinate_Information:
          Planar_Coordinate_Encoding_Method: row and column
          Coordinate_Representation:
            Abscissa_Resolution: 25000
            Ordinate_Resolution: 25000
          Planar_Distance_Units: meters
      Planar:
        Map_Projection:
          Map_Projection_Name: Polar Stereographic
          Polar_Stereographic:
            Straight-Vertical_Longitude_from_Pole: 0.0
            Standard_Parallel: -70.0
            False_Easting: 0.0
            False_Northing: 0.0
        Planar_Coordinate_Information:
          Planar_Coordinate_Encoding_Method: row and column
          Coordinate_Representation:
            Abscissa_Resolution: 25000
            Ordinate_Resolution: 25000
          Planar_Distance_Units: meters
      Geodetic_Model:
        Ellipsoid_Name: Hughes
        Semi-major_Axis: 6378.273
        Denominator_of_Flattening_Ratio: 298.27941

  Entity_and_Attribute_Information:
    Detailed_Description:
      Entity_Type:
        Entity_Type_Label: Ice-concentration grid cell
        Entity_Type_Definition:
          Any of the one-byte data elements in the sea-ice-
          concentration files
        Entity_Type_Definition_Source: self-evident
      Attribute:
        Attribute_Label: Ice-concentration grid cell value
        Attribute_Definition:
          The proportion of the ocean area represented by the grid
          cell that is covered with sea ice.
        Attribute_Definition_Source:
          Calibrations of the SMMR and SSM/I instruments are
          described in the following three publications:

          Gloersen, P., Campbell, W.J., Cavalieri, D.J., Comiso,
          J.C., Parkinson, C.L., and Zwally, H.J., 1993, Arctic and
          Antarctic sea-ice, 1978-1987: Satellite passive-microwave
          observations and analysis: NASA Special Publication no.
          511, 290 p.

          National Snow and Ice Data Center, 1994, Nimbus-7 SMMR
          polar radiances and Arctic and Antarctic sea ice
          concentrations on CD-ROM user's guide, version 3: Boulder,
          Colorado, National Snow and Ice Data Center, 23 p.

          National Snow and Ice Data Center, 1992, DMSP SSM/I
          brightness temperature and sea ice concentration grids for
          the polar regions on CD-ROM, User's guide: National Snow
          and Ice Data Center Special Report 1, [300 p].
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 0
            Range_Domain_Maximum: 100
            Attribute_Units_of_Measure: percent sea-ice cover
            Attribute_Measurement_Resolution: 1
        Attribute_Domain_Values:
          Enumerated_Domain:
            Enumerated_Domain_Value: -99
            Enumerated_Domain_Value_Definition: Missing data
            Enumerated_Domain_Value_Definition_Source: NSIDC
        Attribute_Domain_Values:
          Enumerated_Domain:
            Enumerated_Domain_Value: -88
            Enumerated_Domain_Value_Definition: Land area
            Enumerated_Domain_Value_Definition_Source: NSIDC
    Detailed_Description:
      Entity_Type:
        Entity_Type_Label: ETOPO5 grid cell
        Entity_Type_Definition:
          Any of the two-byte data elements in the files etopo5.n
          and etopo5.s
        Entity_Type_Definition_Source: self-evident
      Attribute:
        Attribute_Label: ETOPO5 grid cell value
        Attribute_Definition:
          Height of the land surface or depth of the sea floor,
          relative to mean sea level.
        Attribute_Definition_Source:
          NOAA/NGDC. 1992. Integrated Global Elevation and
          Bathymetry. Digital Data. NOAA/NGDC/WDC-A, Boulder,
          Colorado. Digital raster data on a 5-minute geographic
          (lat/long) 2160x4320 grid. In: Global Ecosystems Database
          Version 1.0: Disc A. Boulder, CO: NOAA National
          Geophysical Data Center. 1 independent single-attribute
          spatial layer on CD-ROM. 18.6 MB. [First published in
          1989.]
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: -10783
            Range_Domain_Maximum: 8000
            Attribute_Units_of_Measure: meters
            Attribute_Measurement_Resolution: 1

  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Peter N. Schweitzer
          Contact_Organization: Global Change and Climate History Program
        Contact_Address:
          Address_Type: mailing address
          Address:
            Mail Stop 918 National Center
            U.S. Geological Survey
            12201 Sunrise Valley Drive
          City: Reston
          State_or_Province: VA
          Postal_Code: 20192
          Country: USA
        Contact_Voice_Telephone: (703) 648-6533
        Contact_Facsimile_Telephone: (703) 648-6560
        Contact_Electronic_Mail_Address: pschweitzer@usgs.gov

    Resource_Description: U.S. Geological Survey Digital Data Series DDS-27

    Distribution_Liability:
      Although all data and software published on this CD-ROM have been
      used by the USGS, no warranty, expressed or implied, is made by
      the USGS as to the accuracy of the data and related materials or
      the functioning of the software.  The act of distribution shall
      not constitute any such warranty, and no responsibility is assumed
      by the USGS in the use of these data, software, or related
      materials.

    Standard_Order_Process:
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: HDF
          Format_Information_Content: Sea-ice concentration
          File_Decompression_Technique: HDF images compressed with run-length encoding (RLE)
        Digital_Transfer_Option:
          Online_Option:
            Computer_Contact_Information:
              Network_Address:
                Network_Resource_Name: <http://geochange.er.usgs.gov/pub/sea_ice/>
            Online_Computer_and_Operating_System:
              Data General AViiON 6220 system running DG/UX
              version 5.4.2R01 (UNIX)
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: BIL
          Format_Information_Content: Elevation and bathymetry
          Transfer_Size: 51 megabytes
        Digital_Transfer_Option:
          Online_Option:
            Computer_Contact_Information:
              Network_Address:
                Network_Resource_Name: <http://geochange.er.usgs.gov/pub/sea_ice/>
            Online_Computer_and_Operating_System:
              Data General AViiON 6220 system running DG/UX
              version 5.4.2R01 (UNIX)
      Fees: none

  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Organization_Primary:
          Contact_Organization: U.S. Geological Survey Information Services
        Contact_Address:
          Address_Type: mailing address
          Address: Box 25286, Denver Federal Center
          City: Denver
          State_or_Province: CO
          Postal_Code: 80225-0286
          Country: USA
        Contact_Voice_Telephone: 1-888-ASK-USGS
        Contact_Facsimile_Telephone: (303) 202-4693

    Resource_Description: USGS Digital Data Series DDS-27

    Distribution_Liability:
      Although all data and software published on this CD-ROM have been
      used by the USGS, no warranty, expressed or implied, is made by
      the USGS as to the accuracy of the data and related materials or
      the functioning of the software.  The act of distribution shall
      not constitute any such warranty, and no responsibility is assumed
      by the USGS in the use of these data, software, or related
      materials.

    Standard_Order_Process:
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: HDF
          Format_Information_Content: Sea-ice concentration
          File_Decompression_Technique: HDF images compressed with RLE
        Digital_Transfer_Option:
          Offline_Option:
            Offline_Media: CD-ROM
            Recording_Format: ISO 9660 with Apple HFS extensions
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: BIL
          Format_Information_Content: Elevation and bathymetry
          Transfer_Size: 51 megabytes
        Digital_Transfer_Option:
          Offline_Option:
            Offline_Media: CD-ROM
            Recording_Format: ISO 9660 with Apple HFS extensions
      Fees: $32.00

  Metadata_Reference_Information:
    Metadata_Date: 19950831

    Metadata_Contact:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Peter N. Schweitzer
        Contact_Address:
          Address_Type: mailing address
          Address:
            Mail Stop 918 National Center
            U.S. Geological Survey
            12201 Sunrise Valley Drive
          City: Reston
          State_or_Province: VA
          Postal_Code: 20192
          Country: USA
        Contact_Voice_Telephone: (703) 648-6533
        Contact_Facsimile_Telephone: (703) 648-6560
        Contact_Electronic_Mail_Address: pschweitzer@usgs.gov

    Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

    Metadata_Standard_Version: FGDC-STD-001-1998
