to the National Atlas Home page
About | Fact Sheets | Contact Us | Partners | Products | Site Map | FAQ | Help | Follow us on Twitter 
Part of Project LogoAgricultureBiologyBoundariesClimateEnvironmentGeologyGovernmentHistoryMappingPeopleTransportationWater
to the Interactive Map MakerMap LayersPrintable MapsWall MapsDynamic MapsArticlesMapping Professionals

United States Average Annual Precipitation, 1961-1990

Metadata also available as - [Outline] - [Parseable text] - [XML] - [DIF]

Frequently-anticipated questions:


What does this data set describe?

Title: United States Average Annual Precipitation, 1961-1990
Abstract:
This map layer shows polygons of average annual precipitation in the contiguous United States, for the climatological period 1961-1990. Parameter-elevation Regressions on Independent Slopes Model (PRISM) derived raster data is the underlying data set from which the polygons and vectors were created. PRISM is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of annual, monthly and event-based climatic parameters.
Supplemental_Information:
There are many methods of interpolating precipitation from monitoring stations to grid points. Some provide estimates of acceptable accuracy in flat terrain, but few have been able to adequately explain the extreme, complex variations in precipitation that occur in mountainous regions. Significant progress in this area has been achieved through the development of PRISM (Parameter-elevation Regressions on Independent Slopes Model). PRISM is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of monthly and annual precipitation (as well as other climatic parameters). PRISM is well suited to regions with mountainous terrain, because it incorporates a conceptual framework that addresses the spatial scale and pattern of precipitation in such regions.

Detailed descriptions of the PRISM raster data can be found on the Oregon State University PRISM web page at <http://www.ocs.orst.edu/prism/>. Additional information is available through the Natural Resources Conservation Service web pages at the National Water and Climate Center at <http://www.wcc.nrcs.usda.gov/climate/prism.html> or through the National Cartography and Geospatial Center at <http://www.ncgc.nrcs.usda.gov/products/datasets/climate/>.

Other source PRISM data sets are also available in Arc/INFO ASCII GRID format from the Spatial Climate Analysis Service. See <http://www.ocs.orst.edu/prism/products/> for more information.

NRCS offers the source PRISM data packaged on 3 CD-ROM's covering the Lower 48 United States. The CD-ROM's are available as a set for $150.00. The 48 States are broken into three regions: East, Central and West. Each CD contains the annual and monthly precipitation coverages, as well as the gridded data. The CD-ROM's may be ordered through <http://www.ncgc.nrcs.usda.gov/products/datasets/climate/data/precipitation>- order.html>.

  1. How should this data set be cited?

    Chris Daly, Spatial Climate Analysis Service, and George Taylor, the Oregon Climate Service at Orego, 200009, United States Average Annual Precipitation, 1961-1990: Spatial Climate Analysis Service, Oregon State University; USDA - NRCS National Water and Climate Center, Portland, Oregon; USDA - NRCS National Cartography and Geospatial Center, Fort Worth, Texas, Corvallis, OR, USA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -124.762142
    East_Bounding_Coordinate: -66.957227
    North_Bounding_Coordinate: 49.371731
    South_Bounding_Coordinate: 24.545220

  3. What does it look like?

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

    Beginning_Date: 19610101
    Ending_Date: 31-Dec-1990
    Currentness_Reference: Ground condition

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

    Geospatial_Data_Presentation_Form: Map

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains (6243)

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.02083333. Longitudes are given to the nearest 0.02083333. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Area of equal average annual precipitation (described by prismp020.dbf)
    Each polygon represents an area with a constant value for the average annual precipitation, as determined by the PRISM model. (Source: Spatial Climate Analysis Service PRISM Project)

    Shape
    The representation of the entity in the data. (Source: U.S. Geological Survey)

    ValueDefinition
    PolygonA 2-dimensional element.

    Area
    The size of the shape in square coverage units. In the distributed file, coverage units represent square decimal degrees. (Source: Natural Resources Conservation Service)

    Range of values
    Minimum:0.00000
    Maximum:115.09402

    Perimeter
    The perimeter of the shape in coverage units. In the distributed file, coverage units represent decimal degrees. (Source: Natural Resources Conservation Service)

    Range of values
    Minimum:0.00647
    Maximum:874.33448

    Prism0p020
    Internal feature number. (Source: Natural Resources Conservation Service)

    Range of values
    Minimum:2
    Maximum:6244

    Range
    The average annual precipitation. (Source: Spatial Climate Analysis Service)

    Range of values
    Minimum:0.000
    Maximum:200.000
    Units:Inches
    Resolution:2.5


Who produced the data set?

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

    • Chris Daly, Spatial Climate Analysis Service
    • George Taylor, the Oregon Climate Service at Oregon State University

  2. Who also contributed to the data set?

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

    Spatial Climate Analysis Service
    316 Strand Agricultural Hall, Oregon State University
    Corvallis, OR 97331-2202

    541-737-2531 (voice)
    541-737-5710 (FAX)
    daly@coas.oregonstate.edu


Why was the data set created?

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the Spatial Climate Analysis Service, the USDA - NRCS National Water and Climate Center, the USDA - NRCS National Cartography and Geospatial Center, or the U.S. Geological Survey in the use of these data.


How was the data set created?

  1. From what previous works were the data drawn?

    PRISM (source 1 of 7)
    Spatial Climate Analysis Servic, Oregon State University, 1998, Parameter-elevation Regressions on Independent Slopes Model (PRISM): Spatial Climate Analysis Service, Corvallis, OR, USA.

    Type_of_Source_Media: Proprietary software
    Source_Contribution:
    PRISM was used to create gridded estimates of precipitation from point observations and digital elevation model data. For a more detailed description of the PRISM process, see: Daly, C., W.P. Gibson, G.H. Taylor, G.L. Johnson, P. Pasteris. 2002. A knowledge-based approach to the statistical mapping of climate. Climate Research, 22: 99-113, <http://www.ocs.orst.edu/pub/prism/docs/climres02-kb_approach>_ statistical_mapping-daly.pdf>.

    FILTER (source 2 of 7)
    Spatial Climate Analysis Servic, Oregon State University, 1998, Gaussian Filter: Spatial Climate Analysis Service, Corvallis, OR, USA.

    Type_of_Source_Media: Proprietary software
    Source_Contribution:
    The Gaussian filter was used to change the resolution of raster data from 4 km to 2 km. The Gaussian filter was implemented as custom software written in FORTRAN. For information about Gaussian filters see: Barnes, Stanley L., 1964; A Technique for Maximizing Details in Numerical Weather Map Analysis. Journal of Applied Meteorology, 3, 396- 409.

    CLIM81 (source 3 of 7)
    National Climatic Data Center (NCDC), 1991, U.S. National 1961-1990 Climate Normals, Climatography of the United States No. 81 - Monthly Normals: National Climatic Data Center, Asheville, NC, USA.

    Other_Citation_Details:
    For more information on this source, please see <http://www.ncdc.noaa.gov/oa/climate/normals/usnormalshist.html#clim81>.
    Type_of_Source_Media: Online database
    Source_Contribution: Location and values of known average annual precipitation.

    SNOTEL (source 4 of 7)
    Natural Resources Conservation Service (NRCS), 1991, Cooperative Snow Survey Data of Federal-State-Private Cooperative Snow Surveys (SNOTEL): Cooperative Snow Survey Data of Federal-State-Private Cooperative Snow Surveys Annual issue for Western US states, Natural Resources Conservation Service, Portland, OR, USA.

    Other_Citation_Details:
    For more information on this source, please see <http://www.wcc.nrcs.usda.gov/snow/>.
    Type_of_Source_Media: Database, paper, and online
    Source_Contribution:
    Location and values of known average monthly and annual precipitation.

    LOCAL (source 5 of 7)
    Natural Resources Conservation , National Water and Climate Center, Unpublished material, Local precipitation monitoring networks.

    Type_of_Source_Media: Digital files
    Source_Contribution: Location and values of known average annual precipitation.

    DEM (source 6 of 7)
    Agency, Defense Mapping , 1985, 1:250,000-scale Digital Elevation Models (DEM): U.S. Geological Survey, Washington, DC.

    Online Links:

    Type_of_Source_Media: Digital files
    Source_Contribution:
    Terrain surface input to the PRISM model for estimation of precipitation between known points.

    Atlas-ST (source 7 of 7)
    U.S. Geological Survey, 1999, State Boundaries of the United States: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    This file was used to determine the boundary of the data included.

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

    Date: Apr-1998 (process 1 of 7)
    The DEM resolution was changed to 4 km using the Gaussian filter.

    Data sources used in this process:

    • DEM
    • FILTER

    Date: Apr-1998 (process 2 of 7)
    All the station data was combined into one master data set.

    Data sources used in this process:

    • CLIM81
    • SNOTEL
    • LOCAL

    Date: Apr-1998 (process 3 of 7)
    Data from CLIM81, SNOTEL, and LOCAL were incorporated into the PRISM model and combined with the DEM to produce the initial 4 km-resolution PRISM model output.

    Data sources used in this process:

    • PRISM
    • DEM
    • CLIM81
    • SNOTEL
    • LOCAL

    Date: Apr-1998 (process 4 of 7)
    The PRISM model output was converted from 4 km to 2 km using a Gaussian filter.

    Data sources used in this process:

    • FILTER

    Date: Apr-1998 (process 5 of 7)
    The 2 km raster data was contoured using Arc/INFO.

    Date: Apr-1998 (process 6 of 7)
    Adjacent isohyets were converted to areas or polygons using a custom- designed macro (AML) in Arc/INFO.

    Date: Feb-2000 (process 7 of 7)
    The coverage was created by the Spatial Climate Analysis Service using custom software. The Natural Resources Conservation Service, National Cartography and Geospatial Center edited the file in Arc/INFO to match the coastlines and boundaries (Atlas-ST) from the National Atlas of the United States. The data were converted to shapefile format for inclusion in the National Atlas of the United States.

    Data sources used in this process:

    • Atlas-ST

  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?

    Point estimates of precipitation from the U.S. National 1961-1990 Climate Normals were subjected to manual quality control checks by the National Climatic Data Center (NCDC). PRISM precipitation estimates were reviewed by the PRISM Evaluation Group, a panel of climatologists, meteorologists, and hydrologists. The task of this group was to assess the assumptions made by the model and compare model output with the best available precipitation maps from several western States. The group found that the PRISM maps equaled or exceeded the accuracy of the best maps available.

  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?

    This data set includes observations and interpolated values for the 48 contiguous United States and the District of Columbia, for the climatological period 1961-1990. This data set is a compilation of the best available data from the various data sources.

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

    Precipitation data were derived from two main sources, NCDC Climate Normals and NRCS Cooperative Snow Survey Data (SNOTEL). In general, NCDC stations are located at low elevations and in valley bottoms, and encompass the entire United States. SNOTEL stations are located primarily at high elevations in the western United States.

    Polygon and chain-node topology are present. Checks were made to ensure that no two adjacent polygons are labeled with the same precipitation value. A manual spot check was made of peaks, depressions, and islands.


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. Acknowledgement of the PRISM model, the Spatial Climate Analysis Service at Oregon State University, the Natural Resources Conservation Service (NRCS) Water and Climate Center, the NRCS National Cartography and Geospatial Center (NCGC), and (or) the National Atlas of the United States would be appreciated in products derived from these data.

  1. Who distributes the data set? (Distributor 1 of 2)

    USDA - NRCS National Cartography and Geospatial Center
    501 W Felix, PO Box 6567
    Ft. Worth, TX 76115
    USA

    817-509-3366 (voice)
    snechero@ftw.nrcs.usda.gov

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    These spatial datasets, associated metadata and documentation are provided at media cost, without restriction or restraint of use, from the USDA- Natural Resources Conservation Service and the Spatial Climate Analysis Service. The project was directed and sponsored by the NRCS National Water and Climate Center in Portland, Oregon. None of the agencies involved, nor any of their employees, make any warranty, expressed or implied, or assume any legal liability or responsibility for the accuracy, completeness, or misuse of the data, nor represent that its use would not infringe privately owned rights. The agencies involved are not responsible for damage, transmission of viruses, or computer contamination through the distribution of this data set. Neither do they assume any responsibility for the usefulness of any information, apparatus, product, or process disclosed in this metadata. Reference in this metadata to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, the State of Oregon, or any agency thereof. Any views and opinions of authors expressed in this metadata do not necessarily state or reflect those of the United States Government, the State of Oregon, or any agency thereof.

  4. How can I download or order the data?


  1. Who distributes the data set? (Distributor 2 of 2)

    Earth Science Information Center, U.S. Geological Survey
    507 National Center
    Reston, VA 20192

    1-888-ASK-USGS (1-888-275-8747) (voice)

    Contact_Instructions:
    In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>.
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey in the use of these data.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 07-Jun-2006
Metadata author:
Peg Rawson
U.S. Geological Survey
12201 Sunrise Valley Drive
Reston, VA 20192
USA

703-648-4183 (voice)
atlasmail@usgs.gov

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



 


Generated by mp version 2.9.1 on Mon Aug 21 14:55:49 2006