The CMC Numerical Output Database

Meteorological data in GRIB format

The Meteorological Service of Canada makes  this Numerical Weather Prediction (NWP) database available to private sector meteorologists, academics, and the general public.  It contains output from the Canadian Meteorological Centre's GEM model, in both the global and regional configurations.  

There are two main sections in the database:

• A low resolution database, containing GEM output that has been interpolated to a coarser grid than the model's native grid.   This reduces the size of the dataset while preserving ample information for many purposes. The data is free, under standard terms and conditions.  
• A high resolution database, containing GEM model output that has been interpolated on a regular grid of similar resolution to the model's.  This larger dataset is suitable for applications where the finer details of model output are required.  Access to this dataset is free, but requires a written agreement with the MSC.

A description of the GRIB format.

Dataset description and access

Output from the Regional GEM and from the Global GEM is available daily from the 00Z and 12Z runs.  Each file in the database  contains one single GRIB record.  In other words, there is a single file per possible combination of model, parameter, level, level-type, grid, date, and forecast interval.

Further details and access to the low-resolution database
Further details and access to the high-resolution database

Getting started

The Meteorological Service of Canada does not currently distribute GRIB decoding or visualization software to the general public. For your convenience, here are some  external links to GRIB software:

• For general purpose decoding and record manipulation :  wgrib.
• For visualization or re-gridding, GRADS, GEMPAK and NCAR NCL are possible options.

While we acknowledge and are thankful for the efforts of GRIB software developpers, the links above are not meant to be exhaustive or to convey any particular relationship between their authors and the MSC.  Unfortunately, we cannot provide user support for external tools.

If this is your first foray into the world of GRIB data, be prepared to apply significant effort into the learning and setting up of the software tools.

Here are some links to documents detailing the GRIB Edition 1 standard :

WMO GRIB Edition 1 is the authoritative source.

NCEP Office Note 388 contains much of the same information as the WMO document, and also describes the NCEP implementation of the GRIB Edition 1 standard.  Parameters and level types used in publicly available CMC GRIB are compatible with NCEP tables contained in Office Note 388.

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