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

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

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. cliffs 0 bis ? % detritus ~10% Photos: Marcia Phillips

What is permafrost ? Permafrost profile

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

Borehole temperature measurements Borehole locations, Muot da Barba Peider (2980 m ASL, Pontresina, E Swiss Alps) 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

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

First anlayses Trend 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!

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

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

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 ) –hot summer 2003 (snow-free – )  influence of snow and temperature on permafrost

First anlayses: Cumulative ground temperatures

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