Permafrost data Muot da Barba PeiderPermafrost data Muot da Barba Peider- some first analyses –- some first analyses –

Evelyn ZenklusenEvelyn Zenklusen

CCES-Extremes Meeting, 30.04.2008, EPFL

OutlineOutline

• What is permafrost

• Motivation

• Borehole temperature measurements

• First analyses

• Summary & future plans

What is permafrost ?What is permafrost ?

DefinitionDefinition

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 ?What is permafrost ?

Permafrost profilePermafrost profile

MotivationMotivation

thawing permafrost ...

- problems with buildings & constructions (settlements, liftings) - natural hazards (rock slides, debris flows, creeping processes)

Photo: Markus Walser

Photo: Marcia Phillips

Borehole temperature measurementsBorehole temperature measurements

Borehole locations, Muot da Barba Peider

(2980 m ASL, Pontresina, E Swiss Alps)

Logger

Temperature measurementsinside the borehole:0.5m, 1.0m, 2.0m, 3.0m, 4.0m,6.0m, 8.0m, 10.0m, 13.5m, 17.5m

First anlaysesFirst anlayses

Borehole temperatures: observation Borehole temperatures: observation seriesseries

Borehole temperatures Muot da Barba Peider (2980 m.a.s.l.) 04.10.1996-16.07.2007te

mp

era

ture

[°C

]

-6-4

-20

2

19970101 19980101 19990101 20000101 20010101 20020101 20030101 20040101 20050101 20060101 20070101

X0.5.mX1.0.mX2.0.mX3.0.m

X4.0.mX6.0.mX8.0.mX10.0.m

X13.5.mX17.5.m

annual cycle: problem für trend calculation

trend with periodic function

Trend over annual max/min/mean/median/certain day

First anlaysesFirst anlayses

Trend analysis of 1st January temperatureTrend analysis of 1st January temperature

1998 2000 2002 2004 2006

-5-4

-3-2

-10

X0.5.m

tem

pe

ratu

re [°

C]

Trend: -0.0065°C, P-Wert: 0.9583

1998 2000 2002 2004 2006

-5-4

-3-2

-10

X6.0.m

tem

pe

ratu

re [°

C]

Trend: 0.0353°C, P-Wert: 0.0399

1998 2000 2002 2004 2006

-5-4

-3-2

-10

X17.5.m

tem

pe

ratu

re [°

C]

Trend: 0.0329°C, P-Wert: 1e-04

• 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:First anlayses:

Trend analysis for every day of the yearTrend 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

tem

pera

ture

tre

nd [

°C]

-0.2

0-0

.15

-0.1

0-0

.05

0.00

0.05

0.10

1st Jan 1st Feb 1st Mar 1st Apr 1st May 1st Jun 1st Jul 1st Aug 1st Sep 1st Oct 1st Nov 1st Dec 31th Dec

X0.5.mX1.0.mX2.0.mX3.0.m

X4.0.mX6.0.mX8.0.mX10.0.m

X13.5.mX17.5.m

significant not significant

First anlayses:First anlayses:

Annual count of thawing daysAnnual 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

X0.5.m

cou

nt o

f da

ys T

>0

°C

1998 2000 2002 2004 200620

40

60

80

100

rel.trend[%/decade]: 52.9 abs.trend[days/decade]: 32 p-value: 0.2189min: 19 max: 103

X1.0.m

cou

nt o

f da

ys T

>0

°C

1998 2000 2002 2004 200605

101520253035

rel.trend[%/decade]: 180 abs.trend[days/decade]: 6 p-value: 0.5187min: 0 max: 34

X2.0.m

cou

nt o

f da

ys T

>0

°C

1998 2000 2002 2004 2006-1.0

-0.5

0.0

0.5

1.0

rel.trend[%/decade]: 0 abs.trend[days/decade]: 0 p-value: 1min: 0 max: 0

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative 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

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative ground temperatures

X0.5.m (hydrological year)

month

cum

ula

tive

gro

un

d te

mp

era

ture

[°C

]

N D J F M A M J J A S O

-80

0-6

00

-40

0-2

00

0

19971998199920002001

20022003200420052006

20020011

20020033

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative ground temperatures

X2.0.m (hydrological year)

month

cum

ula

tive

gro

un

d te

mp

era

ture

[°C

]

N D J F M A M J J A S O

-80

0-6

00

-40

0-2

00

0

19971998199920002001

20022003200420052006

20020011

20020033

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative ground temperatures

X4.0.m (hydrological year)

month

cum

ula

tive

gro

un

d te

mp

era

ture

[°C

]

N D J F M A M J J A S O

-80

0-6

00

-40

0-2

00

0

19971998199920002001

20022003200420052006

20020011

20020033

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative ground temperatures

X10.0.m (hydrological year)

month

cum

ula

tive

gro

un

d te

mp

era

ture

[°C

]

N D J F M A M J J A S O

-80

0-6

00

-40

0-2

00

0

19971998199920002001

20022003200420052006

2002001120020033

First anlayses:First anlayses:

Cumulative ground temperaturesCumulative ground temperatures

X17.5.m (hydrological year)

month

cum

ula

tive

gro

un

d te

mp

era

ture

[°C

]

N D J F M A M J J A S O

-80

0-6

00

-40

0-2

00

0

19971998199920002001

20022003200420052006

20020011

20020033

Summary & future plansSummary & 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