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Maryland Strata Map

Frequently-anticipated questions:

What does this data set describe?

Title: Maryland Strata Map
Abstract:
The United States Department of Agriculture (USDA), National Agricultural Statistics Service (NASS) area sampling frame is a delineation of all parcels of land for the purpose of later sampling the parcels. The area frame is constructed by visually interpreting satellite imagery to divide a state into homogenous land use areas (strata) based on percent cultivated. The strata are typically defined as low, medium or high percent cultivated, non-agricultural land, urban use, agri-urban, or water. The boundaries of the strata usually follow identifiable features such as roads, railroads and waterways. The strata boundaries do not coincide with any political boundaries, with the exception of state boundaries.
Supplemental_Information: N/A
  1. How should this data set be cited?

    United States Department of Agr, National Agricultural Statistics Service, 1996, Maryland Strata Map: U.S. Department of Agriculture, National Agricultural Statistics Service, Fairfax, Virginia.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -79.29
    East_Bounding_Coordinate: -75.02
    North_Bounding_Coordinate: 39.43
    South_Bounding_Coordinate: 37.54

  3. What does it look like?

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

    Calendar_Date: 2002
    Currentness_Reference:
    1997: Publication date of strata boundaries. 1996: Creation of original area sampling frame strata boundaries.

  5. What is the general form of this data set?

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      Indirect_Spatial_Reference:
      U.S. Department of Commerce, 1990, Counties and Equivalent Entities of The United States, Its Possessions, and Associated Areas (Federal Information Processing Standard 6-4): Washington, D.C. National Institute of Standards and Technology.
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-Polygon (434 (prior to dissolving boundaries))

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75.00
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.00
      False_Northing: 0.0

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 30
      Ordinates (y-coordinates) are specified to the nearest 30
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference 80.
      The semi-major axis of the ellipsoid used is 6378137.00.
      The flattening of the ellipsoid used is 1/298.257.

  7. How does the data set describe geographic features?

    Land Use Strata
    Homogeneous land use area based on percent cultivated (Source: U.S. Department of Agriculture, National Agricultural Statistics Service)

    Strata
    Land use category based on percent cultivated (Source: U.S. Department of Agriculture, National Agricultural Statistics Service)

    Land Use Based on Percent Cultivated
    Value Definition
    13 
     50% cultivated, (cultivated categories consist of land used for
    crops, the remaining portion of land in the cultivated strata may include pasture, woods, waste, rangeland, etc.)
    20 15%-50% cultivated, (cultivated categories consist of land used for crops, the remaining portion of land in the cultivated strata may include pasture, woods, waste, rangeland, etc.)
    31 Agri-urban with > 100 homes per square mile (less than 15% cultivated)
    32 Commercial/dense urban with > 100 homes per square mile (city center with 0% cultivated)
    40 < 15% cultivated, (cultivated categories consist of land used for crops, the remaining portion of land in the cultivated strata may include pasture, woods, waste, rangeland, etc.)
    50 Non-agricultural (state or national parks, military bases, etc.)
    62 Water

    Sum_area
    The stratum area in square miles. (Source: U.S. Department of Agriculture, National Agricultural Statistics Service)

    Stratum Area in Square Miles
    Range of values
    Minimum: 5.2 (actual value, not range)
    Maximum: 957.683 (actual value, not range)

    Sum_acres
    The number of acres in a stratum. (Source: U.S. Department of Agriculture, National Agricultural Statistics Service)

    Number of Acres in Stratum
    Range of values
    Minimum: 3328.0 (actual value, not range)
    Maximum: 612917.12 (actual value, not range)

    Entity_and_Attribute_Overview:
    To retain consistency in symbology with data viewed with ArcView mapping software, the .avl file associated with the black and white strata map requires strata symbol modification for use with ArcGIS. The symbols needing modification are described as Agri-Urban > 100 Homes per sq. Mi. and Non Agriculture. Both symbols use ESRI's 10% simple hatch: outline width: 0.01, offset: 220, separation 1.0 and line width: 0.2. The Agri-Urban line hatch is displayed at 90 degrees and Non-Agriculture displayed at 0 degrees.
    Entity_and_Attribute_Detail_Citation: N/A

Who produced the data set?

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

    • United States Department of Agriculture, National Agricultural

  2. Who also contributed to the data set?

    Area Frame Section staff

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

    Area Frame Section staff
    USDA/NASS/RDD/AFS
    1400 Independence Ave SW, Room 6034
    Washington, D.C. 20250

    703-235-1971 (voice)
    HQ_RD_OD@nass.usda.gov

Why was the data set created?

These data are intended for geographic display and analysis at the state level. The data should be displayed and analyzed at a scale of 1:100,000 or smaller (e.g., 1:250,000, etc.). The strata data are provided "as is". USDA/NASS does not warrant results you may obtain using the strata data.

How was the data set created?

  1. From what previous works were the data drawn?

    TMimagery (source 1 of 6)
    Earth Observation Satellite Company, 1995, Landsat 5 Thematic Mapper imagery: Earth Observation Satellite Company, Lanham, Maryland.

    Type_of_Source_Media: CD-ROM
    Source_Contribution: spatial and attribute information

    US GeoData (source 2 of 6)
    U.S. Geological Survey (USGS), 1989, US DLG vector files: U.S. Geological Survey (USGS), Reston, VA..

    Type_of_Source_Media: CD-ROM
    Source_Contribution: spatial and attribute information

    SureMaps (source 3 of 6)
    Horizons Technology, Inc., 1989, Mosaiced topographic raster: Horizons Technology, Inc., San Diago, CA.

    Type_of_Source_Media: CD-ROM
    Source_Scale_Denominator: 100,000
    Source_Contribution: spatial and attribute information

    SPOT (source 4 of 6)
    Corporation, SPOT Image , 1995, SPOT Image: SPOT Image Corporation, Reston, VA..

    Type_of_Source_Media: CD-ROM
    Source_Contribution: spatial and attribute information

    JES (source 5 of 6)
    National Agricultural Statistics Service, 1995, June Enumerative Survey: National Agricultural Statistics Service, Fairfax, VA.

    Type_of_Source_Media: Survey summary data
    Source_Contribution: Attribute information

    AFSpaper (source 6 of 6)
    National Agricultural Statistics Service, 1987, Area Frame Design for Agricultural Surveys: NASS/USDA, Washington, DC.

    Type_of_Source_Media: paper
    Source_Contribution: attribute information

  2. How were the data generated, processed, and modified?

    Date: 1991 (process 1 of 2)
    The area sampling frame for Maryland was constructed in 1996 for use in 1997 and was based on mosaiced 1:100,000 scale topographic raster data, U.S. Department Of Interior US GeoData, 30-meter pixel resolution Landsat 5 Thematic Mapper imagery and 20 meter pixel resolution SPOT Imagery. Individual county files were merged into a single state file. The coordinates for the strata polygons are unprojected to geographic latitude and longitude (decimal degrees). The spatial data file format is Environmental Systems Research Institute's ArcView shapefile format.

    Data sources used in this process:

    • TopoQuad100
    • TMpaper
    • TopoDRG
    • TM5imagery
    • TM7imagery
    • SPOTimagery
    • JES
    • AFSpaper

    Date: 2004 (process 2 of 2)
    The shapefile was imported into a personal geodatabase where topological checks were performed. The rules must not have gaps and must not overlap were enforced.

  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?

    The sources used for digitizing strata boundaries are 1:100,000 scale topographic raster data

  3. How accurate are the heights or depths?

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

    There are no known gaps or missing data. This data set includes the area in square miles and number of acres for each strata. Because the area sampling frame strata boundaries may not be coincident with strata boundaries of adjacent states.

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

    No checks for topological consistency were performed on this data set.

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:
None. Acknowledgment of the U.S. Department of Agriculture, National Agricultural Statistics Service would be appreciated in products derived from these data.

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

    USDA/NASS/RDD
    1400 Independence Ave SW, Room 6034
    Washington, D.C. 20250

    703-235-1971 (voice)

    Contact_Instructions: N/A
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Users of the strata data are solely responsible for interpretations made from the product. The strata data are provided "as is". USDA/NASS does not warrant results you may obtain by using the strata data. Feel free to contact our staff at (HQ_RD_OD@nass.usda.gov) if technical questions arise in the use of the strata data.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 27-Jul-2004
Metadata author:
Matt Deaton
USDA/NASS/RDD
1400 Independence Ave SW, Room 6034
Washington, D.C. 20250

703-877-8000 x151 (voice)
Matt_Deaton@nass.usda.gov

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

Generated by mp version 2.8.22 on Wed Feb 06 15:54:05 2008