1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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 !

11. 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)

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 12 / 18
Reconstruction of glacier surface mass balance from the SLA
z
b
SLASLAtb 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

20. 12 / 18
Mass balance gradient derived
from field data, valid at a regional
scalez
b
SLASLAtb 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

21. 12 / 18
z
b
SLASLAtb ieq )()(
n
ieq
zb
B
SLA
n
SLA
1 /
1
with:
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

22. 12 / 18
Mean mass balance of the glacier over
the study period computed by DEM
difference
z
b
SLASLAtb ieq )()(
n
ieq
zb
B
SLA
n
SLA
1 /
1
with:
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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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