In many applications (e.g. flood forecasting, agriculture, reservoir management), the amount of water held in the winter snowpack (snow water equivalent or SWE) is of primary importance. SWE essentially represents the depth of water (mm) that would be produced if the snow melted. Weekly or bi-monthly measurements of SWE are commonly made by provincial water resource agencies and hydroelectric companies. These measurements are most often collected by manually extracting a snow core and measuring the depth and mass of the snow sample along pre-determined transects (or snow surveys) to monitor the amount of water stored in the snowpack prior to melt. From 1955 to 1985, Environment Canada published an annual summary of Canadian snow survey data that have been digitized to create a national snow course data set covering the early 1960's to 2003 (MSC, 2000). At peak levels in the early 1980's, there were over 1,700 snow courses operating in Canada, but this number declined to around 800 in the early 1990's. Unfortunately, there are relatively few snow courses with consistent long periods of data for analysing historical variation in SWE.
SWE can also be derived from passive microwave satellite measurements (e.g., Goodison et al., 1986) and has been shown to provide SWE values to within +/- 20 mm of in-situ measurements in the Canadian Prairies (Figure 1; Derksen et al., 2003). Extending satellite estimates of SWE to other environments has proven to be challenging, but validated SWE algorithms have now been developed for the Canadian boreal forest and tundra environments (Derksen, 2008; Derksen et al., 2010). SWE estimates can also be derived from snow depth information as snow density tends to follow a fairly well-defined seasonal evolution that can be estimated from available snow course data (Brown et al., 2003).
Interactive SWE Data of Canadian Prairies
Interactive SWE Data of Northern Hemisphere
Interactive tools on this page were built by CCIN staff.