Numerical Data from the RDPS in GRIB2 format - Coupled to Gulf of St. Lawrence

Brief description of the system

The Atmosphere-Ocean-Ice forecast system for the Gulf of St. Lawrence is a circulation model to better understand Canadian inland seas. This system includes two main parts:

  1. An oceanic pseudo-analysis cycle (Smith et al., 2012) including a superimposed sea ice analysis based on direct insertion of Radarsat image analyses (Smith et al., 2012).
  2. A coupled forecast cycle.

Note that the coupled forecast cycle is a 48 hour simulation based on 00, 06, 12 and 18 UTC data where both of its models (LAM and OCEAN-ICE) run at the same time. It provides 00-48 hour weather, sea ice and ocean forecasts.

Technical Native Grid Specifications (Computational Domain)

The atmospheric component is a limited area configuration (LAM) of the Regional Deterministic Prediction System (RDPS) centered over the Gulf of St. Lawrence (GSL). This grid has 360 x 400 points in the horizontal with a spacing of 10 km (0.09 degrees) on a rectangular latitude-longitude projection. The required lateral boundary conditions for this model configuration are taken at every hour from the operational RDPS forecasts at the same resolution (0.09 degrees).

For the oceanic component, the system uses the NEMO model (Nucleus fro European Modeling of the Ocean) which includes a 3D oceanic circulation model taking into account the tides and freshwater inflows of rivers. The CICE (Community of Ice CodE) model is used for the sea-ice component. The NEMO-CICE domain consists of a 149 x 236 grid in the horizontal direction and extends from the Cabot Strait and Belle Isle Strait to Quebec City and to the head of the Saguenay Fjord near Tadoussac. A one-dimensional hydrological model is used from Montreal to Quebec City to absorb tides. The horizontal resolution is 5 km on a rotated-Mercator projection. The ocean is layered in the vertical with a uniform resolution of 5 m down to 300 m depth and 10 m further below. The surface and bottom layers are adjusted to the water level and local depth respectively. The boundary conditions for river runoffs, temperature and salinity are taken from climatological data and tides are implicitly calculated (Saucier et al. [2003]).

Technical lat-lon Grid Specifications used for GRIB2 product

10 km resolution grid
Table lists the values of various parameters of latitude-longtitude grid
Parameter Value
ni 500
nj 325
resolution 0.02 x 0.03°
coordinate of first grid point 45° 30' N 71° W

GRIB data specifications

The fields in the GRIB2 data set for the two components of the system are made available on a latitude-longitude grid of 500 x 325 (with 0.02 x 0.03 degrees of resolution). The list of fields made available in GRIB2 format are:

Variable Description System
UGRD Zonal component of wind at diagnostic (surface) level [m/s] Atmospheric
VGRD Meridional component of wind at diagnostic (surface) level [m/s] Atmospheric
TMP Sea surface temperature (between 0 and 5m)  [Kelvin] Oceanic
ICEC Ice fraction Oceanic
ICETK Ice thickness (averaged over model grid cell) [m] Oceanic 
UICE Zonal component of Ice speed vector [m/s] Oceanic
VICE Meridional component of Ice speed vector [m/s] Oceanic
UOGRD Zonal component of the surface ocean current [m/s] Oceanic
VOGRD Meridional component of the surface ocean current [m/s] Oceanic
WTMP Sea surface temperature [Kelvin] Oceanic
ICET Ice surface temperature [Kelvin] Oceanic
ICEPRS Vertically integrated ice internal pressure (or stress) [N/m or Pa x m] Oceanic
ICESTG Vertically integrated compressive ice strength [N/m or Pa x m] Oceanic


The data is available using the HTTP protocol and 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 GRIB2 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:


File nomenclature

where: Example of file name:

These files originate from the Canadian Meteorological Center (CMC) and contain the data of the Atmosphere-Ocean-Ice forecast system for the Gulf of St. Lawrence using a latitude-longitude grid of 500 x 325 (with 0.02 x 0.03 degrees of resolution). The forecast has been produced on January 12th 2015 at 00Z (2015011200) and contains the 48 hour forecast (P048) in GRIB2 format (.grib2).


These variables are only available for the surface level.

Data in GRIB2 format


What we are doing

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