AWIPS Map Database Catalog

Purpose:

This catalog assembles and promulgates spatial geographic information issued by the National Weather Service (NWS) for use by the user community. These data consist of a variety of official NWS forecast zones and county designations used by be NWS. In addition other data that might be of interest and that are used by the (NWS) Advanced Weather Information Processing System (AWIPS) are available through the catalog. The published "Shapefile" commercial (ESRI) standard is used for this purpose. The Shapefile format is documented on-line. The publication of commonly used geographic data supports a primary goal of Executive Order (E.O.) 12906, Coordinating Geographic Data Acquisition and Access: The National Spatial Data Infrastructure, 11 Apr 94, which is to reduce duplication of effort within the Federal Government.

The following caveats apply:

1) The NWS is NOT aware of any commercial license or copyright prohibiting the free use and distribution of these data.
2) References to commercial entities or products does not constitute endorsement by the NWS.
3) Accuracy of these data is not guaranteed.

Shapefile description:

Shapefiles provide a complete non-topological description of 2-dimensional geometric shapes, in three files:

filename.shp - shape description
filename.shx - index (shape to attributes)
filename.dbf - attributes

The shape of each geometric (spatial) object is either a point, line, or polygon, and is described completely and in sequential order by the file *.shp. Attributes for each shape are stored sequentially in the same order by the file *.dbf, using the dBASE III+ Database File Structure. An index of shapes to attributes is maintained in the *.shx file. The Shapefile format is documented online. By convention, a Shapefile is associated by one prefix filename. The contents of the *.dbf file can be changed without damaging the index relationship to *.shp as long as dBASE records are not added, deleted or re-ordered. Shapefiles can be renamed, provided that all three components are given the same filename and the extensions are not changed. We have restricted the filenames to 8 characters for compatibility with DOS systems.

Each catalog entry provides an image of the Shapefile. When the geographic area is not obvious, the Shapefile is shown as darker points or lines on a lighter background. Space is conserved using the "zip" compression technique. Public domain software to extract *.zip files are now available for most operating systems and hardware environments from ftp://ftp.uu.net/pub/archiving/zip/. Make sure that the *.zip file has been downloaded using a binary transfer method. Previous archives in the *.tar.Z (UNIX) and self-extracting *.exe (DOS) formats have been deleted.

filename.zip - compressed (zip)
filename.gif - Graphics Interchange Format
filename.txt - flat text listing of filename.dbf

Catalog Entry Description:

Each catlog entry web page usually has the following sections:
A download table consisting of a descripition of the data, a link to download the data set, the valid date of the data set, the size in bytes of the downloadble file and links FGDC compliant metadata and a change log.

File Specifications:

Naming Convention - a description of the name of the Shapefile. Most data in the catalog have a two letter prefix for the type of data and the date in ddmmyy format.
Shapefile Type - type of shape {point, polyline, polygon}
Source - origin of shape and attribute information
Last Modified - last date shapes or attributes modified
File size information: - size of all relavant files in bytes and the number of records in the dataset.

Attributes:

field - dBASE field name (1 to 10 characters)
type - field type {character, numeric, logical, date}
width,dec - field type specifications:
{character: width = # characters} {logical: width = 1} {date: width = 8}
{numeric: width = # digits, dec = # decimal places}
Description - brief statement of field usage.

Comments: Additional information as necessary.


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