Low-resolution CMC GRIB database

Regional GEM at 60 km resolution, Global GEM at 2x2 degrees resolution and ensemble at 2.5 x 2.5 degrees resolution

Access
Dataset description
File name convention
Available parameters

Access

The data resides in a directory that is plainly accessible to a web browser. Visiting that directory with an interactive browser will yield a raw listing of links, each link being a downloadable GRIB file. In practice, we recommend writing your own script to automate the downloading of the desired data(using wget or equivalent). If you are unsure of how to proceed, you might like to take a look at our brief wget usage guide.

The data can be accessed at the following URLs:

• Regional 00Z, 12Z:
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_reg_00
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_reg_12
• Global 00Z, 12Z:
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_glb_00
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_glb_12
• Ensemble 00Z, 12Z:
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_ens_00
  • http://dd.weatheroffice.ec.gc.ca/grib/public/lores/CMC_ens_12

Dataset description

1.  Regional GEM model at 60km resolution

Time parameters

0-48 hours forecast issued twice a day, based on 00Z and 12Z initalization time. Fields on isobaric levels are available at 6-hourly forecast intervals up to 48 hours (9 time slices) while the surface fields are available at 3-hourly intervals (17 time slices).

Levels

Vertical coverage of three-dimensional fields is provided by up to 28 isobaric levels.
Isobaric levels (hPa) : 1015, 1000, 985, 970, 950, 925, 900, 875, 850, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 275, 250, 225 200, 175, 150, 100, 50.

Some fields receive limited three-dimensional coverage of 4 levels in the vertical.

Isobaric levels (reduced coverage, hPa): 850, 700, 500, 250.

Four other level types may be applicable to a given parameter :

1. surface
2. mean sea-level
3. fixed height above ground
4. layer between two isobaric levels

Grid

Low resolution regional grid

The model is run on a variable-step grid with a 15 km central core resolution.  The fields in the low resolution regional GRIB dataset are made available on a 135x95 Polar-Stereographic grid covering North America and adjacent waters with a 60 km resolution at 60° N.

Click on image for further technical information.

Contents

For a list of available fields, see table 1 below.

Global GEM model at 2x2 resolution
0-5 day forecast, with reduced 5-10 day dataset at 00z

Time parameters :

0-120 hour forecasts produced twice a day from 00Z and 12Z initialization times.  All fields are produced at 6-hour intervals.

Levels :

Vertical coverage of three-dimensional fields is provided by up to 28 isobaric levels.

Isobaric levels (hPa) : 1015, 1000, 985, 970, 950, 925, 900, 875, 850, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 275, 250, 225, 200, 175, 150, 100, 50.

Some fields receive limited three-dimensional coverage of 4 levels in the vertical.

Isobaric levels (reduced coverage, hPa): 850, 700, 500, 250.

Four other level types may be applicable to a given parameter :

1. surface
2. mean sea-level
3. fixed height above ground
4. layer between two isobaric levels

Grid

Low resolution global grid

The global GEM model is run on a 1x1 degree uniform grid. The fields in the low resolution global GRIB dataset are made available on a 181x81 latitude-longitude grid at a resolution of 2x2 degrees, which corresponds to about 220 km resolution. The grid is truncated at 80 degrees North and 80 degrees South.

Contents

The meteorological contents of the dataset is identical to the one for the regional GEM dataset, as described in table 1, with the exception that the NT fields and RT fields are not available. Forecast fields are available at 6-hourly intervals up to 120 hours (21 time slices).

Additionally, for the 00Z execution, a small sub-set of the model outputs are available between the 132h and 240h forecasts at 12-hourly increments. The available parameters are:

• geopotential height at 500hPa
• zonal (U) and meridional (V) components of the wind at 250hPa
• MSLP
• accumulated precipitation

Ensemble model at 2.5 x 2.5 degrees of resolution, 0-15 days forecast

For more information about the GRIB data from the ensemble forecast model, please refer to the page describing the CMC ensemble dataset.

File name convention for regional and global data

File names follow the following convention:

example:

Parameter and level-type abbreviations follow the convention established in NCEP Office Note 388. Currently available fields are listed in the table below.

SFC
          

MSL
          

ISBL (28 isobaric levels)
ISBY (layer between two isobaric levels)
SFC
          

ISBL (28 isobaric levels)
TGL (2m above ground)
          

TGL (2m above ground)
          

ISBL (28 isobaric levels)
TGL  (2m above ground)

ISBL (4 isobaric levels)
TGL (2m above ground)
          

ISBL (28 isobaric levels)
TGL (2m above ground)
          

ISBL (28 isobaric levels)
TGL (2m above ground)
          

ISBL (4 isobaric levels)
          

ISBL (4 isobaric levels)
          

SFC
          

SFC
          

SFC
          

NOTE: u and v components of the wind vector are to be resolved relative to the defined grid, in the direction of increasing i and j coordinates. For further details, please consult Code Table 7 of the GRIB standard.

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Created: 2002-12-31

Modified: 2004-07-13

Reviewed: 2002-12-31

URL of this page: http://weather.ec.gc.ca/grib/Low-resolution_GRIB_e.html

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