can the snowline be used as an indicator of the equilibrium-line and mass balance for glaciers in...

Can the snowline be used as an indicator of the

equilibrium-line and mass balance for glaciers in

the outer tropics?

Dr. Antoine Rabatel, Ing. E. Loarte, Dr. A. Soruco, Ing. J. Gomez

August 28, 2009

Ph : B. Pouyaud

Huaraz, 1 - 4 de julio 2013

Laboratorio Mixto Internacional GREAT – ICE

Servicio de Observacion GLACIOCLIM

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Context

2 / 18

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

“The World Glacier Inventory contains information for over 100,000 glaciers through out the

world. Parameters within the inventory include: geographic location, area, length, orientation,

elevation, and classification of morphological type and moraines.”

World Glacier Inventory website

Context

2 / 18

“The World Glacier Inventory contains information for over 100,000 glaciers through out the

world. Parameters within the inventory include: geographic location, area, length, orientation,

elevation, and classification of morphological type and moraines.”

World Glacier Inventory website

“Basic information on specific net balance, cumulative specific balance, accumulation area

ratio and equilibrium line altitude is given for 111 glaciers.”

GMBB #10, WGMS-Zurich, 2009

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Context

2 / 18

0.1 % of the glaciers are monitored at worldscale

Limitation for the study of:

- glacier sensitivity to climate/morphological parameters

- glacier contribution to hydrological systems

“The World Glacier Inventory contains information for over 100,000 glaciers through out the

world. Parameters within the inventory include: geographic location, area, length, orientation,

elevation, and classification of morphological type and moraines.”

World Glacier Inventory website

“Basic information on specific net balance, cumulative specific balance, accumulation area

ratio and equilibrium line altitude is given for 111 glaciers.”

GMBB #10, WGMS-Zurich, 2009

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Context

2 / 18

Remote-sensing is an efficient tool to realize the

measurement of glaciological parameters at a regional scale

0.1 % of the glaciers are monitored at worldscale

Limitation for the study of:

- glacier sensitivity to climate/morphological parameters

- glacier contribution to hydrological systems

“The World Glacier Inventory contains information for over 100,000 glaciers through out the

world. Parameters within the inventory include: geographic location, area, length, orientation,

elevation, and classification of morphological type and moraines.”

World Glacier Inventory website

“Basic information on specific net balance, cumulative specific balance, accumulation area

ratio and equilibrium line altitude is given for 111 glaciers.”

GMBB #10, WGMS-Zurich, 2009

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

3 / 18

Background

Equilibrium line, MB = 0

Acc > Ab

Saint Sorlin Glacier (French Alps)

For mid-latitude glaciers : end-of-summer snowline = equilibrium line

Ab > Acc

The snowline is easy to identify on optical satellite images

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

4 / 18

Background

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

4 / 18

Background

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Background

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

BUT !

5 / 18

5 / 18

Background

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

BUT !

Validation of the method for the outer tropical Andes

Tropical climate generates a sequence of

accumulation and ablation processes all

year round that differs from that of mid-

latitude glaciers.

6 / 18

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Outer tropical Andes (Peru – Bolivia)

7 / 18

Validation of the method for the outer tropical Andes

Ph : B. Pouyaud

Monthly mass balance measurements on

the glacier tongue (5250 – 4850 m a.s.l.)

ELAi for each year i

Mass balance gradient

Zongo Glacier (Bolivia, 16 S)Monitored since 1991

IRD-France and UMSA-Bolivia0

z

b

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

8 / 18

Validation of the method for the outer tropical Andes

Ph : B. Pouyaud

Monthly mass balance measurements on

the glacier tongue (up to 4850 m a.s.l.)

ELAi for each year i

Mass balance gradient

Artesonraju Glacier (Peru, 9 S)Monitored since 2000

UGRH - ANA

z

b

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

9 / 18

Validation of the method for the outer tropical Andes

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

List of the used satellite images

10 / 18

Validation of the method for the outer tropical Andes

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

How to detect the snowline on satellite images?

Test of different combinations of bands and band ratios applied on Landsat-5 image

11 / 18

Validation of the method for the outer tropical Andes

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Comparison of the highest remote-sensed SLA for each year and the annual ELA

11 / 18

Validation of the method for the outer tropical Andes

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Comparison of the highest remote-sensed SLA for each year and the annual ELA

12 / 18

Reconstruction of glacier surface mass balance from the SLA

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

12 / 18

Reconstruction of glacier surface mass balance from the SLA

z

bSLASLAtb ieq )()(

Snowline altitude for each year i of the study

period, computed from satellite images

Snowline altitude representative of a steady state of

the glacier

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

12 / 18

Mass balance gradient derived

from field data, valid at a regional

scalez

bSLASLAtb ieq )()(

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Reconstruction of glacier surface mass balance from the SLA

12 / 18

z

bSLASLAtb ieq )()(

n

ieqzb

BSLA

nSLA

1 /

1with:

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Reconstruction of glacier surface mass balance from the SLA

12 / 18

Mean mass balance of the glacier over

the study period computed by DEM

difference

z

bSLASLAtb ieq )()(

n

ieqzb

BSLA

nSLA

1 /

1with:

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Reconstruction of glacier surface mass balance from the SLA

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

13 / 18

11 glaciers where is available.

Soruco et al., 2009

)0697(B

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Reconstruction of glacier surface mass balance from the SLA

14 / 18

Zongo Glacier (Bolivia, 16 S)

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Reconstruction of glacier surface mass balance from the SLA

Comparison between mass balance

derived from SLA measurements

and field measurements

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

15 / 18

Good consistency between

the glaciers

ENSO is the main forcing of

the interannual variability

El Niño

La Niña

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Reconstruction of glacier surface mass balance from the SLA

Important difference:

between -3.4 m w.e. and

-21.3 m w.e.

16 / 18

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Reconstruction of glacier surface mass balance from the SLA

1) Context & background

2) Validation of the method for the outer tropical Andes

3) Application to the Cordillera Real - Bolivia

Application to the Cordillera Real - Bolivia

Morphological parameters are the

main factors controlling the

difference in volume loss between

the studied glaciers

circles = glaciers with a mean elavation > 5150 m a.s.l.

triangles = glaciers with a mean elavation < 5150 m a.s.l.

17 / 18Dr. A. Rabatel, LMI Great Ice, 1-4 julio 2013

Gracias!See also the poster by Ing. Edwin Loarte et al. for an application in the Cordillera Blanca

Rabatel et al., 2005. J. of Glaciology, 51(175), 539-546

Rabatel et al., 2008. J. of Glaciology, 54(185), 307-314

Rabatel et al., 2012. J. of Glaciology, 58(212), 1027-1036

antoine.rabatel@ujf-grenoble.fr