United States Mean Annual R-factor, 1971-2000

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Christopher Daly of the Spatial Climate Analysis Service, Oregon State University and George Taylor of the Oregon Climate Service, Oregon State University

Publication_Date: 20021010

Title: United States Mean Annual R-factor, 1971-2000

Publication_Information:

Publication_Place: Corvallis, Oregon, USA

Publisher:

Oregon State University

Description:

Abstract:

New climatic data were used as input for developing spatially distributed estimates of R-factor and for the period 1971-2000.  This study required two types of data: (1) station values of R-factor  -  precipitation data were collected, processed, and analyzed for R-factor by a team at the Illinois State Water Survey (ISWS) led by Steven Hollinger.  The resulting data set consisted of 1,842 stations.  Station data were provided in English units (100’s ft-tonf in h-1 ac-1 yr-1); and (2) PRISM spatial grid of 1961-90 mean annual precipitation - a high-quality, peer-reviewed spatial grid of mean annual precipitation (MAP) was obtained from ftp://www.ocs.orst.edu/pub/maps/Precipitation/Total/U.S./us_ppt.14.gz.  Units were mm.  This is the official MAP data set for the USDA, and served as the spatial prediction grid for the interpolation.  It represents the best understanding to date of the patterns and magnitudes of MAP in the U.S.  The grid has a geographic (lat/lon) projection with a spatial resolution of 2.5 minutes (about 4 km cell size).  PRISM was used for interpolation.  The method consisted of (1) obtaining input station data; (2) applying PRISM to develop spatially varying regression functions between R-factor and gridded MAP in log10 space for the conterminous US; and (3) converting the PRISM prediction grids from log10 space back to real space.  The result was a 2.5-minute (~4 km) grid of annual R-factor covering the conterminous United States.   Care should be taken in estimating values at any single point on the map. An estimate for each grid cell is an average over the entire area of that cell; thus, point values can be estimated at a spatial precision no better than half the resolution of a cell.  However, the overall distribution of precipitation features is thought to be accurate. For further information on PRISM, the online PRISM homepage can be found at <URL:http://www.ocs.orst.edu/prism/prism_new.html> .

Purpose:

Display and/or analyses requiring spatially distributed R-factor.

Supplemental_Information:

There are many methods of interpolating climate elements 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 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 a knowledge-based system that uses point data, a digital elevation model (DEM), and other spatial data sets to generate gridded estimates of many 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 orographic processes.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19710101

Ending_Date: 20001231

Currentness_Reference:

Climatological period from which the point observations were taken.

Status:

Progress: Complete

Maintenance_and_Update_Frequency:

None planne .

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -126.020833333333

East_Bounding_Coordinate: -64.979166666667

North_Bounding_Coordinate: 50.020833333333

South_Bounding_Coordinate: 24.062500000000

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: raster data

Theme_Keyword: R-factor

Theme_Keyword: grid cell

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: United States, USA

Access_Constraints:

n/a, no restrictions apply

Use_Constraints:

Acknowledgement of the following agencies in products derived from these data: US Environmental Protection Agency (funding agency),  PRISM Model (interpolation software), Spatial Climate Analysis Service at Oregon State University (interpolation agency), Illinois State Water Survey (provider of station data).

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: George Taylor, Spatial Climate Analysis Service at Oregon State University

Contact_Address:

Address_Type: mailing address

Address:

Strand Ag Hall 326, Oregon Climate Service, Oregon State University

City: Corvallis

State_or_Province: OR

Postal_Code: 97331-2209

Country: USA

Contact_Voice_Telephone: (541) 737-5705

Contact_Facsimile_Telephone: (541) 737-5710

Contact_Electronic_Mail_Address: taylor@coas.oregonstate.edu

Security_Information:

Security_Classification_System: None

Security_Classification: Unclassified

Security_Handling_Description: None

Native_Data_Set_Environment: SunOS, 5.5.1, sun4m UNIX

Data_Quality_Information:

Logical_Consistency_Report:

All data were based on the same averaging period (1971-2000). Similar quality assurance procedures were used with all input data sets.

Completeness_Report:

Point estimates of precipitation originated from the following sources: National Climatic Data Center (NCDC) and the Illinois State Water Survey. All station data were subjected to quality control checks by the NCDC and the Illinois State Water Survey.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Accuracy of this data set is based on the original specification of the Defense Mapping Agency (DMA) 1 degree digital elevation models (DEM). The stated accuracy of the original DEMs are 130 m circular error with 90% probability.

Quantitative_Horizontal_Positional_Accuracy_Assessment:

Horizontal_Positional_Accuracy_Value: 130 m with 90% probability.

Horizontal_Positional_Accuracy_Explanation:

The broad DMA production objective for 1-degree DEM's.

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Grid Cell

Row_Count: 623

Column_Count: 1465

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: .04166666666

Longitude_Resolution: .04166666666

Geographic_Coordinate_Units: Decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: World Geodetic Spheroid 1972 (WGS 1972)

Ellipsoid_Name: WGS72

Semi-major_Axis: 6378135.0

Denominator_of_Flattening_Ratio: 298.26

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: average precipitation grid cell value

Entity_Type_Definition: ASCII values

Entity_Type_Definition_Source: Self-evident

Attribute:

Attribute_Label: average annual R-factor grid cell value

Attribute_Definition: spatially gridded average annual R-factor

Attribute_Definition_Source:

Daly, C., and Taylor. G.H. 2002.  Development of New Spatial Grids of R-factor and 10-yr EI30 for the Conterminous United States.   Spatial Climate Analysis Service, Oregon State University.  Submitted to the US Environmental Protection Agency, Las Vegas, NV.   
    Notice:  The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), funded and managed the research described here under contract #OV1062NAEX. It has been peer reviewed by the EPA and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation by EPA for use.
    Notice:  The U.S. Environmental Protection Agency (EPA) through its Office of Research and Development (ORD), has reviewed and approved this product. Neither the United States Government nor any of its federal employees make any warranty, express or implied, regarding the software contained within. EPA does not guaranatee that this product is free from viruses. The EPA does not routinely provide user support, systems documentation, or periodic updates to users. Mention of trade names or commercial products does not constitute endorsement or recommendation by the EPA for use.

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 20

Range_Domain_Maximum: 10116

Enumerated_Domain:

Enumerated_Domain_Value: <=-1

Enumerated_Domain_Value_Definition: no data available or outside of range domain

Enumerated_Domain_Value_Definition_Source: Spatial Climate Analysis Service PRISM Project

Attribute_Units_of_Measure: (100’s ft-tonf in h-1 ac-1 yr-1) * 10

Attribute_Measurement_Resolution: 1

Distribution_Information:

Distributor:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Spatial Climate Analysis Service

Contact_Address:

Address_Type: mailing address

Address: 316 Strand Agricultural Hall

City: Corvallis

State_or_Province: OR

Postal_Code: 97331

Country: USA

Contact_Voice_Telephone: (541) 737-5705

Contact_Facsimile_Telephone: (541) 737-5710

Contact_Electronic_Mail_Address: taylor@coas.oregonstate.edu

Distribution_Liability:

This dataset was funded by an agency of the United States Government and prepared by Oregon State University. Neither the United States Government nor Oregon State University, nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or misuse of the data, or for damage, transmission of viruses or computer contamination through the distribution of these data sets or for the usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein 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 or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: ARC/INFO ASCII Grid

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address: <URL:http://www.ocs.orst.edu/prism/prism_new.html> or

Fees: none

Technical_Prerequisites:

Geographic data are intended for use in a Geographic Information System (GIS). In addition, this publication contains menu and display programs that operate 16 Mb RAM (absolute minimum), CD-ROM drive with ISO 9660 software driver, Graphics card (640x480 pixels with 256 colors, prefer 1024x1024 with 65,535 colors), Color monitor, mouse, and keyboard.