NOMADS Data
The NOAA National Operational Model Archive and Distribution System (NOMADS) project is a major collaboration designed to provide Web-based access to weather and climate model data. The NOAA NOMADS project includes access to the NCDC, NCEP, and National Coastal Data Development Center data sets.
To access data, go to the NOAA NOMADS website
1. Select “Access” on the left menu. 2. Use the “Quick Access Links” directory to access your desired data set.
For example, if you would like to initialize WRF using NAM 218 12 km data, follow these steps:
1. Select “NAM” under NWP
2. Select “Plot|FTP4u” under “Near Real-Time and Historical” and “NAM.” This will direct you to a data request form. A normal data request, instead of a bulk request, is recommended.
3. Select the date range, data cycle, and forecast hours desired for each cycle.
4. It is optional to generate a control file for analysis fields over all cycles or to generate QuickPlots for supported datasets.
a. Only check the “Generate control file…” option if:
i. You want to view an animation of an analysis field across the model cycles in your collection
ii. You want to plot Lat/Lon vs. time cross sections or time-series across all model cycles.
b. Only check the “Generate QuickPlots” option if you want the QuickPlots feature.
c. For large datasets (or as a default), do not check these two boxes.
5. Once your selections are made, click “Submit Data Request.”
6. Your files are copied, first to a private ftp server, and then to the public ftp server at ftp3.ncdc.noaa.gov. It may take several minutes to complete the transfer. Your files will have an extension that is a 4-digit order number.
a. Data only remains on the anonymous server for three days
7. Click “Select files for FTP”
8. Select the data file(s) and filter for desired vertical levels, variables, or geographic region.
9. To retrieve the files, use the following directions from http://nomads.ncdc.noaa.gov/guide/?name=methods#using-ftp
i. Connect to the FTP server
ii. Use anonymous as the user name
iii. Use your email address as the password
iv. Verify that the directory set up correctly (see below). The order number is sent to your email.
/pub/download/nomads/model-####
v. Select “Start FTP.”
vi. A new page will open with ftp instructions at the bottom.
Use the following commands in the directory where you want the data transferred to
ftp ftp3.ncdc.noaa.gov
<logon as user anonymous with your email as the password>
cd /pub/download/nomads/model-4950
prompt
binary
mget * (multi-get command, which downloads all of the requested files from the public directory)
bye (quits FTP)
* This may take a significant amount of time, depending on the amount of data requested.
Note: For this specific example, NAM 218 data is in GRIB2 format.
More general information regarding the NOAA NOMADS project can be found at http://nomads.ncdc.noaa.gov/nomads.php?name=about A user’s guide can be found at: http://nomads.ncdc.noaa.gov/guide/?name=methods