1. Snow Pack Analyser, March 2010 1 Snow Pack Analyser SPA

2. Snow Pack Analyser, March 2010 2 Contents History Principle of Measurement SPA Snow Parameters SPA System Sensor Setups Examples Summary

3. 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

4. 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 Ice Water Real part Imaginary part Frequency [Hz] Dielectric Constant

5. 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

6. 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

7. 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

8. 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

9. Snow Pack Analyser, March 2010 9 Profile Setup Multiple horizontal sensors at defined levels -> Profile Information

10. 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

11. Snow Pack Analyser, March 2010 11 SPA Installation Combination of sloping and horizontal sensors Suspension springs and winches

12. Snow Pack Analyser, March 2010 12 Displacement ΔL of 10 cm -> 50 cm more Sensor in Snow Snow Mast Sensor ΔLΔL Snow Mast

13. Snow Pack Analyser, March 2010 13 Displacement Davos (Switzerland) - Sloping Sensor - 10 m

14. Snow Pack Analyser, March 2010 14 Davos Davos (Switzerland) – 2660 m

15. Snow Pack Analyser, March 2010 15 Davos Davos (Switzerland) – 2660 m

16. Snow Pack Analyser, March 2010 16 Davos 2006/2007 Davos (Switzerland) - Sloping Sensor - 10 m

17. Snow Pack Analyser, March 2010 17 Davos 2008/2009 Davos (Switzerland) - Sloping Sensors - 10 and 5 m

18. Snow Pack Analyser, March 2010 18 Davos 2008/2009 Davos (Switzerland) - Horizontal Sensors - 10 and 5 m

19. Snow Pack Analyser, March 2010 19 Davos 2008/2009 Davos (Switzerland) - Horizontal Sensors - 10 and 5 m

20. Snow Pack Analyser, March 2010 20 Korsvattnet Korsvattnet (Sweden) – 700 m

21. Snow Pack Analyser, March 2010 21 Korsvattnet Korsvattnet (Sweden) – 700 m

22. 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

23. 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

24. Snow Pack Analyser, March 2010 24 Hindelang Hindelang (Germany) – 980 m

25. 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 BC

26. 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

27. 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

28. 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

29. Snow Pack Analyser, March 2010 29 Sylvensteinspeicher Sylvensteinspeicher (Germany) – 780 m

30. 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

31. Snow Pack Analyser, March 2010 31 Installations Val de Aosta (Italy) Tauplitz (Austria)

32. 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