Snow Hydrology Flashcards
Why is snow hydrology important?
- Flood events
- Rain-on-snow
- Storage of winter precipitation and eventual melt
- Safety (cold temps associated with snow dangerous when power goes out, snow can trap people)
Red River Manitoba
- 1997 river flooded
- Up to 20km beyond banks
- Caused major fires downtown
- Built diversion channels and spill way to save city but causes problems downstream
What are three factors for snow hydrology physical processes?
- Snow Accumulation
- Ablation
- Meltwater Runoff
What is the snow to rainfall ratio?
10cm of snow = 1cm of rainfall in dry and arctic environments, coast will have higher water content
Four simultaneous estimation problems
- The quantity of water held in snow packs
- The magnitude and rate of water lost to the atmosphere by sublimation
- The timing, rate, and magnitude of snow melt
- The fate of melt water
Why is the fate of meltwater of concern?
- will it all melt and run off, or infiltrate and become part of GW
Which hemisphere has the largest snow extent?
Northern has higher max and lower minimums
CCIN
Canadian Cryospheric Information Network
- Collects public info (Govt, universities)
- Enhance public awareness and access to cryospheric information and related data
- Facilitate exchange of information
What are the snow depth departure trends in North America?
- Most spots show large negative departure from normal
- Some in Northern parts are slightly above
Optimal Interpolation
- Statistics based grid
- Minimal variance, similar to kriging
- Creates interpolation
Why do we expect to see fluctuations in snow extent in North America?
- Because it is precip driven
- Sublimation may occur
- Wind transffering snow to lower/warmer elevation
How do we see if fluctuations in snow extent in North America are within normal ranges?
- Use +/- 1 standard deviations to see if fluctuations are within normal range
Why was snow extent elevated in North America in 2015-2016?
- Polar Vortex
What are the 3 spatial scales for snow cover distribution?
- Macroscale
- Mesoscale
- Microscale
Fractals
Same pattern at a multitude of scales
Macroscale snow cover
- Up to 10^6 km^2
- Characteristic of Distances 10-1000km
- Larger scale meteorological effects are important
- Air mass characteristics
Mesoscale snow cover
- Characteristic of distances of 100m - 10km
- Redistribution of snow along relief features due to wind
- Deposition and accumulation of snow may be related to terrain variables and vegetation cover
Microscale snow cover
- Characteristic of distances of 10-100m
- Differences in accumulation result from variations in air flow patterns and transport
- Local flow patterns and turbulence
Snow cover in vegetated areas
- Influenced by vegetation density and type and its influence on winds
- More accumulation in cleared areas (20-45%)
How does vegetation (tree) type influence snow cover?
- More deep snow on ground with deciduous
- Less deep snow with coniferous trees due to more snow landing on branches
- More interception on coniferous than bare branched deciduous