Web services providing access to official data for navigating modelled surface currents
Three Web mapping services for surface currents were developed by the Canadian Hydrographic Service (CHS) in collaboration with the Operational Oceanography scientific team of Fisheries and Oceans Canada and are available under licence. These three services are:
- A WMS that produces dynamic images of the data according to the specified parameters.
- A WFS that recovers the raw data behind the images.
- A WCS that recovers raw data from only the raster layers.
To access these web services, simply follow the steps described in these technical specifications.
Web surface current services disseminate the results of various current forecast models. Each model covers a geographic area and produces data based on unique parameters, in particular, the level of detail (spatial and temporal resolution), temporal scope (number of days in the future) and frequency of forecast updates.
The first two models put into operation cover the Gulf of St. Lawrence and the St. Lawrence Estuary. Other models across the country will be added over time.
Gulf of St. Lawrence
The forecasts of surface currents in the Gulf of St. Lawrence are extracted from a three-dimensional ocean model coupled to the Canadian Meteorological Service's atmospheric forecast model (Environment Canada). The ocean model integrates the influence of tides, freshwater runoff, atmospheric forcing, and sea ice. The two models—ocean and atmospheric—provide daily forecasts for the upcoming 48-hour. The ocean model results have been validated within scientific and operational programs of Fisheries and Oceans Canada. The validation includes a number of comparisons with various ocean measurements: currents, water levels, water temperature and salinity, and sea-ice drift, concentration and thickness. The model's forcing data include:
- Tides at Cabot and Belle-Isle straits;
- Freshwater runoff at Québec City;
- Atmospheric forecasts from the Global Environmental Multiscale (GEM) model (Canadian Meteorological Centre, Meteorological Service of Canada, Environment Canada), which provide data on winds, air temperature, cloud cover and relative humidity;
- Sea ice observations integrated into daily charts from the Canadian Ice Service, Environment Canada.
St. Lawrence Estuary, from Trois-Rivières to Cap de Bon-Désir
The surface current forecasts for the St. Lawrence Estuary result from a three-dimensional numerical model. The ocean model integrates tidal influence and mean freshwater runoff from the St. Lawrence River (no influence of the spring freshet) without wind forcing. Model results were validated with a statistically significant series of drifting buoy tracks in calm weather conditions. Tides are responsible for a high percentage of the energy from currents in this region, but the forecasts must be used with caution during intense or extreme wind conditions and in spring freshet conditions.
Access and restrictions
Please take a moment to read through the licence.