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NOAA Atlas 14 Precipitation Frequency Estimates
in GIS Compatible Format

This web page provides access to NOAA Atlas 14 precipitation frequency estimates (with upper and lower bounds of the 90% confidence interval) in GIS compatible format. For Volumes 2 and 3, only partial duration series (PDS)-based grids are available for download; annual maximum series (AMS)-based grids can be calculated by applying ratios from Table 4.6.2 from corresponding NOAA Atlas 14 documents. For NOAA Atlas 14 Volume 1, and Volume 4 and above, both, AMS- and PDS-based grids are available for download. Please note that the precipitation frequency estimates for each volume of NOAA Atlas 14 were computed independently using all available data at the time. Some discrepancies between volumes at project boundaries are inevitable and they will generally be more pronounced for rarer frequencies.


To display and interpret the data, two separate files are needed:
  1. Zipped ASCII grids - These files contain the final, spatially interpolated, high-resolution NOAA Atlas 14 precipitation frequency estimates with confidence limits, and are the basis for the PFDS interface results.

  2. Grid metadata file - These files contain information on projection, grid resolution, precipitation units, and other details relevant to data shown in ASCII grid files. Grid metadata files are in the XML format and are automatically downloaded with zipped ASCII grids. The grid metadata files can be also viewed and downloaded separately below.
The files either can be downloaded 1) via pull-down menu, 2) by anonymous ftp or 3) via web browser. Ftp is recommended for multiple-file downloads. To obtain precipitation frequency estimates without downloading files, please visit the PFDS interface.

1) Via pull-down menu:

2) By anonymous ftp:
Action Type this
Open ftp to the server: ftp
Login as anonymous user: anonymous
Give the password (your email id):
Switch to binary mode: binary
Change directory: cd pub/hdsc/data/xx/ (replace "xx" with an abbreviation, abbreviations can be found at the top of the page in parenthesis, i.e. "sw" for Semiarid and California)
Get one file: Example: mget (this will download the 100-year 24-hour ArcInfo ASCII grid for the Volume 2: Ohio River Basin and Surrounding Areas)
Get several files Example: mget orb* (The wildcard '*' in this case will get all frequencies for the 24-hour duration)
Quit ftp: quit

3) Via web browser: alternatively you can peruse the ftp directory via a browser.

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Page Author: HDSC webmaster
Page last modified: October 6, 2014
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