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ForestERA Metadata - Aspect

Description

Abstract

This is a 90m resolution layer describing aspect on the western Mogollon Plateau in Arizona. It was derived from a digital elevation model (DEM) by the Forest Ecosystem Restoration Analysis (ForestERA) project to support landscape-scale forest restoration planning efforts by a broad group of stakeholders including federal and state agencies, academic institutions, and non-governmental entities.

The 7.5-minute digital elevation model data are digital representations of cartographic information in a raster form developed by the United States Geological Survey. The DEMs consist of an array of elevations for ground positions at regularly spaced intervals. The data are produced in 7.5- by 7.5-minute blocks and stored as profiles with a 10 or 30-meter square grid spacing along and between each profile. The DEM data for 7.5-minute units correspond to the USGS 7.5-minute topographic quadrangle map series for all of the United States and its territories except Alaska.

Purpose

This layer was developed by the ForestERA project for use in landscape-level planning and prioritization of forest management on the western Mogollon Plateau. It was designed for multiple purposes, including wildlife habitat modeling, fire behavior modeling, modeling forest management, and forest management planning.

Supplementary Information

The aspect layer is a derivative of a Digital Elevation Model (DEM). Digital Elevation Models are created by the United States Geological Survey (USGS) using interpolation techniques and one of two elevation data sources; either digitized cartographic map contour overlays or scanned National Aerial Photography Program (NAPP) photographs and specific ground locations where elevation has been precisely measured. See the USGS web site describing Digital Elevation Models (http://edc.usgs.gov/guides/dem.html) for more specific information on the methodologies used in their creation. A number of additional layers, including slope aspect, and various terrain attributes, can be derived from a DEM (Jones et al. 2000; Environmental Monitoring and Assessment 64: 227-245). This slope layer is provided in units of degrees.

The Digital Elevation Model and all of its derivatives meet USGS standards for accuracy. The USGS assesses the accuracy of DEM data by comparing linear interpolation elevations in the DEM with corresponding map location elevations and computing the statistical standard deviation or root-mean-square error (RMSE) for all differences between the two. See the USGS web site describing Digital Elevation Models (http://rockyweb.cr.usgs.gov/nmpstds/demstds.html) for more specific information on accuracy standards and the methodology for accuracy assessment. For the DEMs used in this project, 90 percent of the predicted elevation values are expected to lie within 23 feet (7m) of the actual value and the remaining 10 percent are expected to lie within 50 feet (15m) of the actual value.

These data are intended for regional analyses over spatial extents on the order of tens to hundreds of thousands of acres, and were not developed for use at finer spatial scales, although they may be useful for some applications at those finer scales.

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Status of the data

Complete
Data update frequency: None planned

Time period for which the data is relevant

Description:
publication date

Publication Information

Who created the data: Forest Ecosystem Restoration Analysis Project

Date and time: February 1, 2004
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Data storage and access information

File name: aspect90m
Type of data: raster digital data

Location of the data:

\\ENVSCI41\Shared\metadata_layers\newgrids\aspect\aspect90m
Data processing environment: Microsoft Windows 2000 Version 5.0 (Build 2195)
Service Pack 4; ESRI ArcCatalog 8.1.2.671

Accessing the data

Size of the data: 22.968 MB
Data transfer size: 22.968 MB

Constraints on accessing and using the data

Access constraints: This layer may be accessed by any interested party. It is
provided by the Forest Ecosystem Restoration Analysis project, the Ecological
Restoration Institute (ERI), and Northern Arizona University (NAU).

Use constraints:

This layer is provided for public use by the ForestERA project, ERI, and NAU.
Reports, presentations, and publications in which this layer is presented or
used for analytical purposes should acknowledge the ForestERA project.

Details about this document

Contents last updated: 20040509 at time 14300500

Who completed this document

Forest Ecosystem Restoration Analysis Project
Center For Environmental Sciences and Education:
Northern Arizona University
Flagstaff, Arizona 86011-5694
United States
928-523-0068 (voice)
928-523-7423 (fax)

Contact Instructions:
Contact Dr. Thomas D. Sisk or the Forest Ecosystem Restoraton Analysis Project.

Standards used to create this document

Standard name: FGDC Content Standards for Digital Geospatial Metadata
Standard version: FGDC-STD-001-1998
Time convention used in this document: local time
Metadata profiles defining additonal information
ESRI Metadata Profile: http://www.esri.com/metadata/esriprof80.html

Horizontal coordinate system

Projected coordinate system name: NAD_1983_UTM_Zone_12N
Geographic coordinate system name: GCS_North_American_1983
Details
Grid Coordinate System Name: Universal Transverse Mercator
UTM Zone Number: 12
Transverse Mercator Projection
Scale Factor at Central Meridian: 0.999600
Longitude of Central Meridian: -111.000000
Latitude of Projection Origin: 0.000000
False Easting: 500000.000000
False Northing: 0.000000

Planar Coordinate Information

Planar Distance Units: meters
Coordinate Encoding Method: row and column
Coordinate Representation
Abscissa Resolution: 90.000000
Ordinate Resolution: 90.000000

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
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Bounding coordinates

Horizontal
In decimal degrees
West: -113.044931
East: -109.878536
North: 35.587479
South: 34.107751
In projected or local coordinates
Left: 314687.387285
Right: 601607.387285
Top: 3938195.572581
Bottom: 3775925.572581
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Spatial data description

Raster dataset information
Raster format: ESRI GRID
SDTS raster type: Grid Cell
Number of raster bands: 1
Raster properties
Origin location: Upper Left
Has pyramids: FALSE
Has colormap: FALSE
Data compression type: Default
Display type: matrix values
Cell information
Number of cells on x-axis: 3188
Number of cells on y-axis: 1803
Number of cells on z-axis: 1
Number of bits per cell: 32
Cell Size
X distance: 90.000000
Y distance: 90.000000

No detailed attribute information is available.

Page last updated February 11, 2005