Canadian Seasonal to Inter-annual Prediction System (CanSIPS) - GRIB2 format

Description of the system

The Canadian Seasonal to Inter-annual Prediction System is a long-term prediction system whose objective is to forecast the evolution of global climate conditions. CanSIPS is a multi-model ensemble (MME) system using two climate models developed by the Canadian Centre for Climate Modelling and Analysis (CCCma). It is a fully coupled atmosphere-ocean-ice-land prediction system relying on the operationnal data assimilation infrastructure for the initial state of the atmosphere, sea surface temperature and sea ice. For further technical information about CanSIPS please refer to the technical note.

Principal components of CanSIPS

  1. Assimilation mode: CanSIPS uses a continuous assimilation cycle for the following 3D atmospheric variables: temperature, wind and humidity. The oceanic variables: sea surface temperature and the sea ice are also assimilated by the system. The assimilated data are provided by the global atmospheric analysis available every 6 hours and the daily sea surface temperature and sea ice analysis. Also a 3D ocean temperature analysis is integrated to CanSIPS trial field before launching the integration.
  2. Forecast mode: The CanSIPS forecasts are based on a 10-member ensemble of forecasts produced with each of two CCCma climate models for a total ensemble size of 20. Monthly to multi-seasonal forecasts extending to 12 months are issued on the first day of each month.
  3. Hindcast mode: CanSIPS climatology is based on series of historical forecasts covering the period 1981-2010. This climatology of the system is very useful for the interpretation of the forecast since the anomaly is generally used instead of the actual raw forecast.

Description of GRIB available data

The fields in the CanSIPS global GRIB dataset are made available on a 145x73 latitude-longitude grid at a resolution of 2.5x2.5 degrees. This is the standard grid for the international exchanges of the World Meteorological Organisation (WMO).

For both the forecast and the hindcast parts, the available data is the monthly mean of the forecast for each member. Also note that each file contains the 12 monthly mean for the lead time from zero month to 11 months. To consult the complete variable list, refer to the variables section.

CanSIPS on global Lat-Long grid

CanSIPS global grid

Grid specifications

Table lists the values of various parameters of the CanSIPS lat-lon grid.

Parameter Value
ni 145
nj 73
resolution 2.5°
coordinate of first grid point 90° S 0° E

Download

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 user guide.

The data can be accessed at the following URLs:

where:

  • forecast: constant string indicating that the file contains the data from the forecast part of CanSIPS, in opposition to the hindcats part.
  • hindcast: constant string indicating that the file contains the data from the hindcast part of CanSIPS, in opposition to the forecast part.
  • MM: Month of the forecast start [01,02,03,...,12]
  • YYYY : Year of the forecast start [2012,2013,...]

File nomenclature

The files have the following nomenclature:

  • Filename for the forecast: cansips_forecast_raw_latlon2.5x2.5_VAR_YYYY-MM_allmembers.grib2
  • Filename for the hindcast: cansips_hindcast_raw_latlon2.5x2.5_VAR_YYYY-MM_allmembers.grib2

where:

  • cansips: constant string indicating that the data is from the CanSIPS system.
  • forecast: constant string indicating that the file contains the data from the forecast part of CanSIPS, in opposition to the hindcats part.
  • hindcast: constant string indicating that the file contains the data from the hindcast part of CanSIPS, in opposition to the forecast part.
  • raw: constant string indicating that the file contains raw data without bias correction
  • latlon2.5x2.5: constant string indicating the latitude-longitude projection at a resolution of 2.5x2.5 degrees.
  • VAR: Variable type included in this file. To consult a complete list, refer to the variables section
  • MM: Month of the forecast start [01,02,03,...,12]
  • YYYY: Year of the forecast start [2012,2013,...]
  • allmembers : constant string indicating that all members [01,02,03,...,20] are grouped into the file.
  • grib2: constant string indicating the GRIB2 format is used.

Example of file name: cansips_forecast_raw_latlon2.5x2.5_HGT_ISBL_0500_2012-10_allmembers.grib2

This GRIB2 file originates from CMC CanSIPS system. The data in the file have a start time on the first day of October 2012. The variable in the file is the monthly mean of the geopontential height at 500hpa, for all the members of the ensemble. The projection used is the latitude-longitude projection at a resolution of 2.5x2.5 degrees.

Levels

The data are available at surface and for certain isobaric levels (for details, refer to the variables section).

Description of the available variables