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Permafrost data Muot da Barba Peider - some first analyses – Evelyn Zenklusen

Permafrost data Muot da Barba Peider - some first analyses – Evelyn Zenklusen. CCES-Extremes Meeting, 30.04.2008, EPFL. Outline. What is permafrost Motivation Borehole temperature measurements First analyses Summary & future plans. cliffs 0 bis ? %. What is permafrost ? Definition.

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Permafrost data Muot da Barba Peider - some first analyses – Evelyn Zenklusen

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  1. Permafrost data Muot da Barba Peider- some first analyses – Evelyn Zenklusen CCES-Extremes Meeting, 30.04.2008, EPFL

  2. Outline • What is permafrost • Motivation • Borehole temperature measurements • First analyses • Summary & future plans

  3. cliffs 0 bis ? % What is permafrost ?Definition permafrost or permafrost soil - soil at or below the freezing point of water (0 °C) for two or more years. - ice is not always present, but it frequently occurs - most permafrost is located in high latitudes, but alpine permafrost may exist at high altitudes in much lower latitudes. rock glaciers ~80% vol. Photos: Marcia Phillips detritus ~10%

  4. What is permafrost ?Permafrost profile

  5. Motivation Photo: Markus Walser thawing permafrost ... - problems with buildings & constructions (settlements, liftings) - natural hazards (rock slides, debris flows, creeping processes) Photo: Marcia Phillips

  6. Temperature measurements inside the borehole: 0.5m, 1.0m, 2.0m, 3.0m, 4.0m, 6.0m, 8.0m, 10.0m, 13.5m, 17.5m Borehole temperature measurements Borehole locations, Muot da Barba Peider (2980 m ASL, Pontresina, E Swiss Alps)

  7. First anlaysesBorehole temperatures: observation series • annual cycle:problem für trend calculation •  trend with periodic function • Trend over annual max/min/mean/median/certain day

  8. First anlaysesTrend analysis of 1st January temperature • linear regression • t-test • analogue analyses for annual • mean, max, min and median • temperatures • for all: significant increasing • temperature trends only in • deeper layers • no clear trends in upper layers • short time series!

  9. First anlayses:Trend analysis for every day of the year • deeper layers: significant positive trends • intermediate layers: no clear trends • top layer: positive trends in summer and autumn

  10. First anlayses:Annual count of thawing days • Thawing day: day with temperature > 0°C • Logistic regression • Thawing days only exist in upper levels • No clear trends visible  Trend in temperature > 0°C of all days

  11. First anlayses:Cumulative ground temperatures • for every year: add up daily temperature • hydrological year: 1st Nov – 31th Oct • keep in mind: • early & snowy winter 2001 (snow cover 01.11.2000 -12.07.2001) • hot summer 2003 (snow-free 17.06.2003 – 03.09.2003)  influence of snow and temperature on permafrost

  12. 2001 2003 First anlayses:Cumulative ground temperatures

  13. 2001 2003 First anlayses:Cumulative ground temperatures

  14. 2001 2003 First anlayses:Cumulative ground temperatures

  15. 2001 2003 First anlayses:Cumulative ground temperatures

  16. 2003 2001 First anlayses:Cumulative ground temperatures

  17. Summary & future plans • Trend over observation series, annual cycle  trend with periodic function • Extreme values (limited data base with annual min/max)  trend for data over threshold • Link permafrost temperature with snow cover and air temperature • Look at other boreholes allocated in Switzerland

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