Getting NetCDF atmospheric data from THREDDS Data severs


By Cédric H. David  


13 July 2006, updated 21 February 2007





Unidata's THREDDS (Thematic Realtime Environmental Distributed Data Services) Data Servers offer the possibility to download NetCDF CF-1 files.  This tutorial will show how to get data from two THREDDS Data Servers: Motherlode (served by Unidata) and NOMADS (served by NCDC).  The methods given here can be applied for any part of the continental U.S.



Unidata's THREDDS Data Server (named Motherlode) can be found at:



NetCDF files can be downloaded from any of the available datasets.  The 12 km resolution of the North American Model for Continental US can be used as an example (NCEP Model Data / NCEP-NAM-CONUS_12 km / File access).


Browsing through the website to this location, the following can be found:



Any of the 30 files are model results, every 6 hours for the past 7 days.  NAM is a forecast model only. Each file has 84 hours of forecast every 3 hours.


Select one file, for example the first one (here called NAM_CONUS_12km_20070115_1800.grib2 but the name will change depending on the latest forecast available).


The following page appears:


Click on the link given on Access / 4. NetCDFServer.  This link brings you to a web interface to query netCDF file:


You can decide on a time window, a bounding box, and the grids (variables) you are interested in.  The defaults values correspond to the entire geographic domain for the bounding box and all forecast hours.


Click on submit, and save your file!


You will get a NetCDF file with CF-1 convention, for the model you chose (here NAM 12k), with the parameters of your interest, in your own Lat-Long box.



NCDC's THREDDS Data Server (named NOMADS) can be found at:


North American Regional Reanalysis (NARR) data are available from NOMADS.


Again, by browsing down to individual datasets, you will have access to the netCDF server.  For example, the NARR-B monthly dataset for July 2003 is accessible at the following URL: 



The link to the netCDF server for this dataset is the fourth one (4. NetcdfServer), it gives access to the following page:



Here again, you can select your longitude – latitude box and your parameters of interest.  However, only one time is available (0.0).