ENVIRONMENT YUKON






 

Frozen

Snow accumulation

 

Significance

 

The accumulation of snow is determined through measuring the snow water equivalent at survey stations across Yukon. This is a measurement of the liquid water volume held within a snowpack that can be available when melted.

  • Larger snowpacks (with more water) contribute to an increased likelihood of higher spring flows . Therefore, measuring the snow accumulation through snow water equivalent is a major component of spring flood forecasting.
  • The size of snowpack can also influence the timing and severity of river ice break-up.
  • Larger snowpacks (deeper snow) act to further insulate the ground surface from cold winter air temperatures and can further promote permafrost thaw.
  • Many other processes also have the potential to be influenced by changes in snow water equivalent including wildfire risk, shifts in vegetation, soil thermal regimes, and transportation.
  • Warming spring air temperatures over the past several decades leads to earlier snowmelt, and this trend is expected to continue.
  • Climate change projections generally indicate an increase in winter precipitation over a shorter snowfall period, and a higher proportion of precipitation occurring as rainfall. These contradicting processes to snow accumulation may induce a complex response that may vary significantly by region and over time.

 

Wolf Creek snow survey.

 

 

What is happening?

 

There has been a significant increase in the snow water equivalent, measured at three of the 14 long-term snow survey stations analysed. None of the sites measured showed significant decreasing trends. Including all 14 locations, the average increase in snow water equivalent per decade is 3 per cent. There are no stations with long-term records available in the far north of the territory.

Since the trends were last updated, there have been two years of below average snow throughout most of the territory. This has resulted in three locations that previously indicated significant increasing trends (Watson Lake, Frances River, and King Solomon Dome) to fall slightly below what is considered statistically significant (p-values <0.1). The influence of recent years does not change the overall interpretation of the data, which in general, suggest an increasing maximum snowpack over time, resulting from an increase in winter precipitation.

 

Figures 1-4: Snow accumulation in upper Yukon drainage

 

[[slider::./images/report-water-snow-accumulation-figure-1.png|./images/report-water-snow-accumulation-figure-2.png|./images/report-water-snow-accumulation-figure-3.png|./images/report-water-snow-accumulation-figure-4.png]]

  • The stations at both Log Cabin and Meadow Creek showed significant increasing trends in snow accumulation; these were +6 per cent and +4 per cent per decade, respectively.

 

Figures 5-6: Snow accumulation in Liard drainage

 

[[slider::./images/report-water-snow-accumulation-figure-5.png|./images/report-water-snow-accumulation-figure-6.png]]

  • Recently low snow years have resulted in no significant trends within the Liard drainage.
Figures 7-10: Snow accumulation in Central Yukon drainage

 

[[slider::./images/report-water-snow-accumulation-figure-7.png|./images/report-water-snow-accumulation-figure-8.png|./images/report-water-snow-accumulation-figure-9.png|./images/report-water-snow-accumulation-figure-10.png]]

  • There were no significant trends noted at any of the Central Yukon stations.

 

Figures 11-14: Snow accumulation in Lower Yukon – Peel drainage

 

[[slider::./images/report-water-snow-accumulation-figure-11.png|./images/report-water-snow-accumulation-figure-12.png|./images/report-water-snow-accumulation-figure-13.png|./images/report-water-snow-accumulation-figure-14.png]]

  • May Airport shows a significant increasing trend in snow accumulation of 5 per cent per decade.

 

Dog mushing in Ibex Valley. F. Mueller.

 

Taking action

 

The Department of Environment’s Water Resources staff continue to collect data, as do their partners in Yukon’s remote areas including private contractors and staff from the Department of Energy, Mines and Resources. Water Resources compiles and quality controls all snow accumulation data.

 

Snowmobiling at Fish Lake. Marten Berkman.

 

Data quality

  • Access archived snow survey bulletins:
    http://www.env.gov.yk.ca/air-water-waste/snow_survey.php
  • Current snow survey data from across Alaska and Yukon can be viewed on an interactive map made available through a United States Department of Agriculture webpage.
  • There are currently 52 snow survey stations located across Yukon, with an additional four in adjacent areas of Alaska and British Columbia that are used by Water Resources. Most areas of Yukon have good spatial coverage with the exception of the far north, where stations are sparse.

 

Further information

References

A.I. McLeod (2011). Kendall: Kendall rank correlation and Mann-Kendall trend test. R package version 2.2. Available from: https://CRAN.R-project.org/package=Kendall.

H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2009.