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Data and products of the Water Cycle Prediction System (WCPS)

The Water Cycle Prediction System (WCPS) simulates the complete water cycle, following the water as it moves from the atmosphere to the surface, through the river network and into lakes, and back to the atmosphere. It provides short-term analysis and forecasts of atmosphere-ocean-ice and river flows. WCPS was originally implemented over the Laurentian Great Lakes and St. Lawrence River watershed in support of Canada's obligations under the Boundary Waters Treaty (International Joint Commission 2016). Starting from WCPS v3.0.0, the domain is extended to cover also the Gulf of St. Lawrence ocean region.

WCPS consists of three components: Pseudo_analysis component with the ocean-ice model NEMO-CICE, Forecast component with the limited area version of the atmospheric model GEM (GEM-LAM) coupled with NEMO-CICE and Rivers component with the river routing model WATROUTE. These components are coupled to each other, representing processes in the atmosphere, at the land surface and in the soil (at 10 km resolution), in large bodies of water and marine ice (at 1-km resolution), and in rivers (at 1-km resolution).

The Global Deterministic Prediciton System (GDPS) provides initial and boundary conditions to GEM-LAM covering the eastern North America, which includes the oceanic area surrounding the Gulf of St. Lawrence. Every 6 minutes, GEM-LAM communicates with NEMO-CICE of the precipitation that has landed on the surface of the lakes and of the state of the near-surface atmosphere over the Great Lakes (Lakes Superior, Michigan-Huron, St. Claire, Erie, and Ontario) and over the Gulf of St. Lawrence region. NEMO informs GEM-LAM of the surface water temperature, the extent of the ice cover, and the fluxes of latent and sensible heat and momentum. GEM-LAM also provides hourly estimates of surface runoff to WATROUTE. In turn, WATROUTE informs NEMO of the terrestrial runoff.


How to access the data

This data is available on the MSC GeoMet API / web services and the MSC Datamart data server:

An overview and examples to access and use the Meteorological Service of Canada's open data is available.


The end-user licence for Environment and Climate Change Canada's data servers specifies the conditions of use of this data.

MSC Open Data Service Usage Policy

The MSC Open Data Service Usage Policy determines what constitutes an acceptable use of MSC Open Data services and provides users best practices for optimal use.


The metadata of the Water Cycle Prediction System - Ocean-Atmosphere is available on the Open Government Portal.

Technical documentation


The chronology of changes to the Water Cycle Prediction System (WCPS) is available here.