1. Snow Pack Analyser, May 2009 1 Snow Pack Analyser SPA

2. Snow Pack Analyser, May 2009 2 Contents History Principle of Measurement SPA Snow Parameters SPA System Sensor Setups Examples Summary

3. Snow Pack Analyser, May 2009 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, May 2009 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, May 2009 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, May 2009 6 SPA System Sensor –Length between 3 and 10 m (standard 5m) –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 analyzer –Multiplexer for 1 to 4 cables –Calculation of snow parameters –RS 232 data output

7. Snow Pack Analyser, May 2009 7 Measurement and Control Unit Sensor 1 Sensor 2 Sensor 3 Sensor 4 Snow Depth 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, May 2009 8 Common Setup Combination of sloping and horizontal sensors -> Snow parameters of integral snow cover -> Additional data at specific levels

9. Snow Pack Analyser, May 2009 9 Profile Setup Multiple horizontal sensors at defined levels -> Profile Information -> For research of snow pack layers; viewing the snow’s absorption of rain and melting process

10. Snow Pack Analyser, May 2009 10 Area Setup Star shaped installation of multiple sensors -> Data with high areal information -> Remote sensing pixel size for satellite imaging

11. Snow Pack Analyser, May 2009 11 Davos Davos (Switzerland) – 2660 m

12. Snow Pack Analyser, May 2009 12 Davos Davos (Switzerland) – 2660 m

13. Snow Pack Analyser, May 2009 13 Davos 2006/2007 Davos (Switzerland) - Sloping Sensor - 10 m

14. Snow Pack Analyser, May 2009 14 Davos 2008/2009 Davos (Switzerland) - Sloping Sensors - 10 and 5 m

15. Snow Pack Analyser, May 2009 15 Davos 2008/2009 Davos (Switzerland) - Horizontal Sensors - 10 and 5 m

16. Snow Pack Analyser, May 2009 16 Davos 2008/2009 Davos (Switzerland) - Horizontal Sensors - 10 and 5 m

17. Snow Pack Analyser, May 2009 17 Korsvattnet Korsvattnet (Sweden) – 700 m

18. Snow Pack Analyser, May 2009 18 Korsvattnet Korsvattnet (Sweden) – 700 m

19. Snow Pack Analyser, May 2009 19 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 snow pillow -> Begin of run-off A B

20. Snow Pack Analyser, May 2009 20 Run-Off Forecast A C B Point A Snow compression SWE constant Point B Significant increase of liquid water content prior to the start of run-off (point C) Point C Run-off starts SWE decreases Davos (Switzerland) - Sloping Sensor - 10 m

21. Snow Pack Analyser, May 2009 21 Hindelang Hindelang (Germany) – 980 m

22. Snow Pack Analyser, May 2009 22 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

23. Snow Pack Analyser, May 2009 23 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

24. Snow Pack Analyser, May 2009 24 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

25. Snow Pack Analyser, May 2009 25 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

26. Snow Pack Analyser, May 2009 26 Summary On-site 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 –Flood Warning –Maximization of use and storage of water in reservoirs –Improved forecasting of wet snow avalanches Not influenced by ice layers Simple installation even at hillsides