WACCM Download Subset

ACOM subset downloads are unstable as of November 25, 2023. Please check that you have received all chemical variables.

WACCM results for a subset of the globe and a range of dates can be downloaded from this page. Output is provided every 6 hours. Each request is provided as a single netcdf file. We strongly recommend that you download a single day for your region to check the file size and then request a range of dates that will result in a manageable file size.

The WACCM forecasts are driven by meteorological fields from the NASA GMAO GEOS-5 model. This simulation uses anthropogenic emissions from the latest CAMS inventory. Open fire emissions are from FINN-v1 (Wiedinmyer et al., Geosci. Model Devel., 2011). The results are at 0.9x1.25 degrees with 88 levels. Each file (global for 1 day) is 8 GB. Direct data download is also avalailable from the NCAR Research Data Archive; registration is required. See instructions for mozbc.

If you would like to be notified when WACCM forecast data is not going to be available, please subscribe to the ACOM Forecast Notification list. For inquiries regarding WACCM output please register for and submit questions to the CESM Forum.

The 'date' and 'datesec' variables contain the date and time of the WACCM output. To verify the date of the downloaded files, please use 'ncdump -v date'. For output prior to 21 June 2019, the variable 'time_bnds' may display erroneous time intervals (for example, when using ncview).

WACCM results are available from 20 August 2019 until 2 weeks ago. Requests for time spans longer than 32 days are not supported. For more recent data via http, please register for WACCM Direct Download.

Please enter your contact information in the space below:

  • E-mail:
November 23, 2020: The personal data (e-mail) that you provide to UCAR/ACOM here is necessary to identify you as a user of WACCM model output and to notify you when your data packet is ready. We also provide update notices by e-mail. The optional personal data provided below will be used to organize discussion forums (example). We do not use your personal data outside of UCAR/ACOM, and we share only non-personal aggregated data for reporting purposes to third parties. For more information about Privacy at UCAR, see UCAR’s Privacy and Cookies Notices.

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  • Intended usage (optional):
  • I allow ACOM to retain my contact information for notification of updates and possible collaboration. If you want us to remove your information later, please let us know.

Enter the lat-lon and date bounds of the region to extract:

To specify a box that crosses the Greenwich Meridian, enter longitude values like: 340 West and 20 East (from 20W to 20E).
North latitude (-90.0 to 90.0):
West longitude (0.0 to 360.0):
East longitude (0.0 to 360.0):
South latitude (-90.0 to 90.0):

Starting date: Ending date:

Submit your data request here:

Tagged CO tracers are included in the WACCM forecasts (labeled CO01 to CO09) and are based on subsets of CO emissions:
CO01: global biomass burning
CO02: North America anthropogenic
CO03: Europe
CO04: Northern Africa
CO05: Western Asia
CO06: East Asia
CO07: South America
CO08: Southern Africa
CO09: Australia
11874 downloads since 2018-01-23.