Post on 19-Jan-2016
Snow Pack Analyser, March 2010 1
Snow Pack Analyser SPA
Snow Pack Analyser, March 2010 2
Contents
• History
• Principle of Measurement
• SPA Snow Parameters
• SPA System
• Sensor Setups
• Examples
• Summary
Snow Pack Analyser, March 2010 3
History
• Snowpower: EU research project– FZK Karlsruhe (Germany)– SLF Davos (Switzerland)– KTH Stockholm (Sweden)– Hydro-Quebec (Canada)– INRS (Canada)– Sommer (Austria)
• Sensor Development and Improvement
• Snow Pack Analyser SPA
2001
.
.
2004
2004...
2008
2009
Test site Davos, SLF
Test site Quebec, Hydro Quebec
Snow Pack Analyser, March 2010 4
Principle of measurement
• Three components of snow: ice, water and air• Frequency dependence of dielectric constants• Measuring of complex impedance at minimum two frequencies• Estimation of the volume contents of the components• Calculation of the density• Calculation of SWE in combination with snow depth
IceWater
Real part
Imaginary part
Frequency [Hz]
Die
lect
ric
Const
ant
Snow Pack Analyser, March 2010 5
SPA Snow Parameters
• Snow density
• Snow water equivalent SWE
• Contents of ice and liquid water in snow
• Snow depth
• Snow temperatures (optional)– Profile– Ground– Surface
Snow Pack Analyser, March 2010 6
SPA System
• Sensor– Length between 3 and 10 m– Width of 6 cm
• Suspension– Sloping or horizontal installation– Displacement sensor
• Snow Depth Sensor– Transit-time measurement of ultrasonic pulse– Temperature compensation
• Measurement and control unit– Impedance analyser– Multiplexer for 1 to 4 cables– Calculation of snow parameters– RS 232 data output
Snow Pack Analyser, March 2010 7
Measurement and Control Unit
Sensor 1
Sensor 2
Sensor 3
Sensor 4
Snow Depth
Displacement
Temperatures
DC 10..15 V
RS 232
Output Data:
Sensor 1..4
- Density
- SWE
- Liquid Water Content
- Ice Content
- Snow Depth
- Temperatures
SPA
Snow Pack Analyser
Input Data:
Sensor 1..4
- Length
- Top Level
- Bottom Level
Snow Pack Analyser, March 2010 8
Common Setup
Combination of sloping and horizontal sensors-> Snow parameters of integral snow cover-> Additional data at specific levels
Snow Pack Analyser, March 2010 9
Profile Setup
Multiple horizontal sensors at defined levels-> Profile Information
Snow Pack Analyser, March 2010 10
Area Setup
Star shaped installation of multiple sensors-> Data with high areal information-> Up to remote sensing pixel size
Snow Pack Analyser, March 2010 11
SPA Installation
Combination of sloping and horizontal sensors
Suspension springs and winches
Snow Pack Analyser, March 2010 12
Displacement
ΔL of 10 cm -> 50 cm more Sensor in Snow
Snow
MastSensor
ΔL
Snow
Mast
Snow Pack Analyser, March 2010 13
Displacement
Davos (Switzerland) - Sloping Sensor - 10 m
Snow Pack Analyser, March 2010 14
Davos
Davos (Switzerland) – 2660 m
Snow Pack Analyser, March 2010 15
Davos
Davos (Switzerland) – 2660 m
Snow Pack Analyser, March 2010 16
Davos 2006/2007
Davos (Switzerland) - Sloping Sensor - 10 m
Snow Pack Analyser, March 2010 17
Davos 2008/2009
Davos (Switzerland) - Sloping Sensors - 10 and 5 m
Snow Pack Analyser, March 2010 18
Davos 2008/2009
Davos (Switzerland) - Horizontal Sensors - 10 and 5 m
Snow Pack Analyser, March 2010 19
Davos 2008/2009
Davos (Switzerland) - Horizontal Sensors - 10 and 5 m
Snow Pack Analyser, March 2010 20
Korsvattnet
Korsvattnet (Sweden) – 700 m
Snow Pack Analyser, March 2010 21
Korsvattnet
Korsvattnet (Sweden) – 700 m
Snow Pack Analyser, March 2010 22
Korsvattnet 2008/2009
Korsvattnet (Sweden) - Horizontal Sensor - 5 m
Point A
Increase of liquid water content
No changes in snow depth and snow pillow
-> Begin of melting process
Point B
At about 7-8 % liquid water content
Decrease of SWE on snow pillow
-> Begin of run-off
A
B
Snow Pack Analyser, March 2010 23
Run-Off Forecast
A
B
C
Point A
Snow compression
SWE constant
Point B
Run-off starts
SWE decreases
Point C
Significant increase of liquid water content prior to the start of run-off (point B)
Davos (Switzerland) - Sloping Sensor - 10 m
Snow Pack Analyser, March 2010 24
Hindelang
Hindelang (Germany) – 980 m
Snow Pack Analyser, March 2010 25
Snow Cover with Ice Layers
Hindelang (Germany) – Sloping Sensor – 5 m
Point A
SPA and snow pillow show similar data
Point B
Appearance of ice layers in snow pack
Point C
Snow depth stays constant
Snow pillow fluctuates
SPA does not fluctuate
A
B
C
Snow Pack Analyser, March 2010 26
Foehn Event
Hindelang (Germany) – Sloping Sensor – 5 m
Point A
Temperature > 0°C
Slight increase of snow density and liquid water content
Point B
Foehn event causes sudden increase of liquid water content above saturation of snow pack
-> run-off situation
-> risk of wet snow avalanches
A
B
Snow Pack Analyser, March 2010 27
Daily Variation of Liquid Water
Hindelang (Germany) – Horizontal Sensor – 5 m
Point A
High liquid water content
Points B
Slight increase of liquid water above saturation causes sudden rise of liquid water.
This liquid water is reduced by run-off.
-> Buffer behavior of snow regarding to liquid water
A B
Snow Pack Analyser, March 2010 28
Daily Variation of Liquid Water
Hindelang (Germany) – Horizontal Sensor – 5 m
Point A
Maximum of air temperature
Point B
Begin of increasing water content
-> Shift between air temperature and liquid water content
A
B
Snow Pack Analyser, March 2010 29
Sylvensteinspeicher
Sylvensteinspeicher (Germany) – 780 m
Snow Pack Analyser, March 2010 30
Sylvensteinspeicher 2009/2010
Sylvenstein (Germany) - Horizontal Sensor - 5 m
Point A
Increase of liquid water content
No changes in SWE snow depth decreases
-> Begin of melting process
Point B
At about 6 % liquid water content
Decrease of SWE on snow pillow
-> Begin of run-off
A
B
Snow Pack Analyser, March 2010 31
Installations
Val de Aosta (Italy)Tauplitz (Austria)
Snow Pack Analyser, March 2010 32
Summary
• In-situ measurement of snow parameter– Liquid water content– Snow density – Snow water equivalent– Snow depth
• Specific setup of sensors– Integral snow pack– Profile data– High areal information
• Forecasting the start of water run-off
• Not influenced by ice layers
• Simple installation even at hillsides