A METHOD FOR MONOTORING GLACIER MASS BALANCE USING REMOTE SENSING IN THE FRENCH ALPS : COMPARISON WITH GROUND MEASUREMENTS (1985-2003) Jean-Pierre DEDIEU,

A METHOD FOR MONOTORING GLACIER MASS BALANCE USING REMOTE SENSING

IN THE FRENCH ALPS :

COMPARISON WITH GROUND MEASUREMENTS (1985-2003)

Jean-Pierre DEDIEU, Antoine RABATEL, Christian VINCENT, Alvaro SORUCO

Laboratoire de Glaciologie et de Géophysique de l’EnvironnementCNRS - Grenoble, France.

http://www.lgge.obs.ujf-grenoble.fr

8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

Glaciers Monitoring from Space Glaciers Monitoring from Space

InputInput : Additions of trends towards improvement in : Additions of trends towards improvement in : :

* Spatial and spectral resolutionSpatial and spectral resolution

* Frequency of repeat coverageFrequency of repeat coverage

* Radiometric calibrationRadiometric calibration

** Geometric fidelityGeometric fidelity

* Stereo capabilitiesStereo capabilities

OutputOutput : National and International projects : National and International projects


GLIMS : Global Land Ice Measurements from Space (http://www.glims.org)

World glaciers database (ASTER satellite images)

Glacier Inventory at regional scale (Optical satellite images)

Mer de Glace 26.09.2000 © Spot Image


© Landsat ETM7 – 30.07.2001 Géant

Leschaux

TalèfreChamonix

Swiss Glacier Inventory (http://www.geo.unizh.ch) Landsat satellite images

Evolution 1973-2000 (by Fanck PAUL, Andreas KAAB & al.)

Mischabel mountain range

Aletsch glacier region


Objective : Glacier net mass balance

Ablation area

Accumulation area

Photo : M. Caplain

EEquilibriumline

Mass balance = Accumulation + AblationExpressed in meter water equivalent

MB<0

MB>0MB=0

Martin Gerbaux

St.Sorlin Glacier, 28-09-1986 (© Louis Reynaud) St.Sorlin Glacier, 05-10-1986 (© Spot-Image)

dz

dbZ ELAt annual Mass Balance annual Mass Balance

derived from ELA byderived from ELA by

where db/dz = 0.78 m w.e./100 m (1985-2003)

FOCUS: Equilibrium Line Altitude variations

Remote Sensing databaseFrench Glaciers Observatory Service (LGGE-OSUG, Grenoble)

ARGENTIERE N 45°87/ E 6°90 West, 19 km2

GEBROULAZ N 45°19/ E 6°40 North, 3.2 km2

St. SORLIN N45°10/ E 6°10 North-East, 3 km2

1. Satellite data : 1985-20031985-2003

Remote Sensing processing (optical and SAR data)

© SPOT-Image 26/08/2000 SPOT-Image 26/08/2000

© Radarsat 26/10/1996

Raw Image

D.E.M.

- Geometric and radiometric corrections, ratios thresholds (PCI inc. )

- annual ELA digitized measurement

++


2. Ground data :2. Ground data : direct measurements (stakes)

Bilan Argentière 2001-2002

19021802

1702

20022102

2302

2402

602702

1002y = 0,0115x - 33,213R2 = 0,9776

-3

-2,5

-2

-1,5

-1

-0,5

0

0,5

1

2600 2700 2800 2900 3000

Bilan Argentière-2000-2001

5011001

601

801

21012001

1901

1701201

y = 0,0087x - 23,478R2 = 0,9594

-2,00

-1,50

-1,00

-0,50

0,00

0,50

1,00

1,50

2,00

2,50

3,00

2500 2600 2700 2800 2900 3000 3100

Regression line = ELA, d(b)/d(z)8th Circumpolar Symposium on Remote Sensing of Polar Environments - June 8 -12, 2004 Chamonix, France

1 . E L A V a r ia tio n 1 9 9 4 -2 00 2 (G ro u n d m ea su rem en ts )

2 6 0 0

2 7 0 0

2 8 0 0

2 9 0 0

3 0 0 0

3 1 0 0

3 2 0 0

3 3 0 0

1 9 9 4 -1 9 9 5

1 9 9 5 -1 9 9 6

1 9 9 6 -1 9 9 7

1 9 9 7 -1 9 9 8

1 9 9 8 -1 9 9 9

1 9 9 9 -2 0 0 0

2 0 0 0 -2 0 0 1

2 0 0 1 -2 0 0 2

A rge n t iè reSa in t So r linGébr o ulaz

-

-A n n é e A rg e n tiè re S a in t-S o rl in G é b ro u la z1994-1995 2674 2788 28251995-1996 2821 3016 31001996-1997 2777 2906 30461997-1998 2946 3094 31951998-1999 2811 2946 30401999-2000 2829 2969 30412000-2001 2695 2837 29132001-2002 2888 3003 3044

Err e u r -Ty p e 2 4 3 3 7 3

EL A (m . a .s. l . )

R esu lts


2. db/dz variation 1994-2002:2. db/dz variation 1994-2002:

Mean Value St.Sorlin/Gébroulaz/Argentière : 0,78 0,78 m water equivalentm water equivalent

0,000

0,002

0,004

0,006

0,008

0,010

0,012

0,014

1994-1995

1995-1996

1996-1997

1997-1998

1998-1999

1999-2000

2000-2001

2001-2002

ArgentièreSaint SorlinGébroulaz

--

Année Saint Sorlin Argentière Gébroulaz1994-1995 0,51 0,78 0,331995-1996 0,85 0,66 0,471996-1997 0,75 0,83 0,51997-1998 0,96 1,04 0,691998-1999 0,86 1,01 0,561999-2000 1,1 0,99 0,592000-2001 0,83 0,75 0,462001-2002 1,15 1,11 0,7

Moyenne 0,88 0,90 0,54

Erreur-Type 0,06 0,11 0,07

Coefficient d'activité db/dz (m eq. eau)


3. ELAs and specific net balance comparison (1994-2002):

ELA vs b(t). 1994-2002

R2 = 0,8365

R2 = 0,8068

R2 = 0,8813

2500

2700

2900

3100

3300

-2,5 -2 -1,5 -1 -0,5 0 0,5 1

b(t) m.w.e

EL

A m

.

Argentière Saint Sorlin Gébroulaz

a. Field measurements (stakes)

R2 = 0,938

R2 = 0,9822R2 = 0,9296

2500

2600

2700

2800

2900

3000

3100

3200

3300

2600 2700 2800 2900 3000 3100 3200 3300

Measured ELAs (m. asl)C

ompu

ted

EL

As

(m. a

sl)

Argentiere

St. Sorlin

Gebroulaz

Linéaire(Argentiere)Linéaire(Gebroulaz)Linéaire (St.Sorlin)

b. Field versus Remote Sensing


4. Comparison of cumulative specific net balance between reconstructed and direct measurements

b(t) = ( ELAeq – ELAi ) * db/dz, where ELAeq = 1/n ΣELAi - < b(t) > * db/dz

© SPOT-Image 1986 SPOT-Image 1986

4.1. Methodology: Gebroulaz glacier (1986-2003)


Hydrological Remoted ELA b(t) b(t) Cumulative b(t) b(t) cumulativeYear ELA variation Remoted Remoted Ground Ground

1986-1987 2950 -31,12 -0,17 -0,84 -0,89 -0,891987-1988 2880 38,88 0,21 -0,63 0,14 -0,751988-1989 3050 -131,12 -0,71 -1,34 -1,76 -2,511989-1990 2980 -61,12 -0,33 -1,67 -0,36 -2,871990-1991 3037 -118,12 -0,64 -2,30 -0,87 -3,741991-1992 3026 -107,12 -0,58 -2,88 -1,17 -4,911992-1993 2980 -61,12 -0,33 -3,21 0,94 -3,971993-1994 2982 -63,12 -0,34 -3,55 -0,64 -4,611994-1995 2800 118,88 0,64 -2,91 0,50 -4,111995-1996 2984 -65,12 -0,35 -3,26 -0,50 -4,611996-1997 3012 -93,12 -0,50 -3,77 -0,21 -4,821997-1998 3175 -256,12 -1,38 -5,15 -1,54 -6,361998-1999 2981 -62,12 -0,34 -5,48 -0,29 -6,651999-2000 3034 -115,12 -0,62 -6,11 -0,17 -6,822000-2001 2900 18,88 0,10 -6,00 0,46 -6,362001-2002 3050 -131,12 -0,71 -6,71 -0,40 -6,762002-2003 3250 -331,12 -1,79 -8,50 -1,65 -8,41

Mean Value 3006,33

Total Mass balance -8,50Annual mean value -0,47

ELAeq (m.a.s.l) 2919

Specific d(b)/d(z) 0,0066 mwe

Photogrammetric Balance 1986-2003


4.2. Preliminary results: Gebroulaz glacier (1986-2003)

a. Surface mass balance (t) at ELA area

b. Cumulative specific mass balance b(t)

-2,00

-1,50

-1,00

-0,50

0,00

0,50

1,00

1,50

1986-1987 1989-1990 1992-1993 1995-1996 1998-1999 2001-2002

Hydrological year

Mass b

ala

nce (

mw

e)

B(t) Remoted

B(t) Ground

-10,00

-9,00

-8,00

-7,00

-6,00

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

1986-1987 1989-1990 1992-1993 1995-1996 1998-1999 2001-2002

Hydrological year

Cu

mu

lati

ve m

ass b

ala

nce (

m.w

.e)

b(t) cumulative remoted

b(t) cumulative ground

4.3. Meteorological corrections and final results (1994-2002)

Gébroulaz corrected

-3,00

-2,50

-2,00

-1,50

-1,00

-0,50

0,00

0,50

1,00

1,50

19

94

-19

95

19

95

-19

96

19

96

-19

97

19

97

-19

98

19

98

-19

99

19

99

-20

00

20

00

-20

01

20

01

-20

02

b(t) Remoted cumulb(t) Ground cumul

Gébroulaz

-3,50-3,00-2,50-2,00-1,50-1,00-0,500,000,501,001,502,00

19

94

-19

95

19

95

-19

96

19

96

-19

97

19

97

-19

98

19

98

-19

99

19

99

-20

00

20

00

-20

01

20

01

-20

02


Saint Sorlin

-7,00

-6,00

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

1,00

19

94

-19

95

19

95

-19

96

19

96

-19

97

19

97

-19

98

19

98

-19

99

19

99

-20

00

20

00

-20

01

20

01

-20

02


St.Sorlin corrected

-7,00

-6,00

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

1,00

1994

-199

5

1995

-199

6

1996

-199

7

1997

-199

8

1998

-199

9

1999

-200

0

2000

-200

1

2001

-200

2


Argentière

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

1,00

19

94

-19

95

19

95

-19

96

19

96

-19

97

19

97

-19

98

19

98

-19

99

19

99

-20

00

20

00

-20

01

20

01

-20

02


Argentière corrected

-5,00

-4,00

-3,00

-2,00

-1,00

0,00

1,00

19

94

-19

95

19

95

-19

96

19

96

-19

97

19

97

-19

98

19

98

-19

99

19

99

-20

00

20

00

-20

01

20

01

-20

02


a. Raw remoted b(t) before correction

b. after Cumulated Positive Degree-Day correction (Meteo-France data)


Limitations :The extreme summer 2003 and its effects on alpine glaciers

Glacier b(t) m we 2002-2003 ELA m asl

Argentière (19 km2, N) - 2.10 3200 St. Sorlin (3 km2, NE) - 2.80 3400 Gebroulaz (3 km2, N) - 1.65 3220 Sarennes (0.5 km2, S) - 3.15 3400

© Landsat TM5 26/09/1985© Landsat TM5 26/09/1985 © ASTER 12/08/2003© ASTER 12/08/2003

Sarennes Glacier (Cemagref, since 1949)

Ice Snow Rocks

Conclusions and outlook

• Mass balance reconstruction results are validated

by direct ground measurements on :

2 glaciers + 8 cycles, 1 glacier + 17 cycles to study deeply

• ELAs yearly maps can be produced by Remote Sensing at the mountain range scale (gradient)

• Method of interest for climate change impact


St. Sorlin Glacier , 1987

Thanks for your attention . . .Thanks for your attention . . .

Documents

A METHOD FOR MONOTORING GLACIER MASS BALANCE USING REMOTE SENSING IN THE FRENCH ALPS : COMPARISON WITH GROUND MEASUREMENTS (1985-2003) Jean-Pierre DEDIEU,