Snow Monitoring and Glaciers Mass Balance from SPOT/VEGETATION
Vanessa Drolon Else Swinnen Etienne Berthier Philippe Maisongrande
Copyrights E. Berthier
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
15 years of monitoring
devoted to various thematic Issues
• NDVI as a proxy of LAI, productivity
• Evapotranspiration and water budget
• SWVI as a proxy of Water stress
• Land use land cover
• Water bodies, Snow and Glaciers
NDVI = ρ
pir-ρ
rougeΡ
pir+ρ
rougeNDSI = ρ
mir-ρ
visΡ
mir+ρ
visNormalized Difference
Vegetation Index
Normalized Difference Snow Index
Vegetation and Snow index
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
LANDSAT vs VEGETATION Snow Cover
High-Atlas mountains
(Morocco)
NDSI
sn ow c ov er r at io Snow Monitoring
Altitude 2600-4200m
0 200 400
Snow surface (km²)
North South
Optimal snow indices NDSI
Space time dynamics of snow cover sensitivity to elevation & exposure
0 0,5 1
Snow cover proportion
1000-1400m 1400-1800m 1800-2200m 2200-2600m 2600-3000m 3000-3400m 3400-3800m 3800-4200m
Boudhar et al. Sècheresse 2007. Chaponnière et al. International Journal of Remote Sensing. 2005
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
50 100 150 200 250 300 350 400 450 500 20
40
60
80
100
120
140
NDSI applications
50 100 150 200 250 300 350 400 450 500
20 40 60 80 100 120
140 -0.6
-0.4 -0.2 0 0.2 0.4 0.6
Pas de neige σ(NAO de août à octobre) = 1,35
σ(NAO de août à octobre) = 0,7 σ(NAO de août à octobre) = 0,1
Snow coverage climatology
Internannual variability, trends in extent & duration, etc…
Sensitivity to meteo. e.g.NAO…
Hydrology & Glaciers Mass Balance
The Sea Level Rise and its causes
1993 2010 Global Sea Level Rise
Cazenave & Llovel; Church et al. 2011
Observed SLR +3.2 mm/a Thermosteric
Dilatation
+1.0 mm/a Polaires ice caps +0.6 mm/a
Glaciers +0.9 mm/a
Sea Level Rise (Kemp et al. 2011) For 2000 years = 0.5 mm/year, 100 ans = 1.7 mm/year
0.24 ± 0.15 mm/y due to Antarctic
0.2 mm/y due to Himalaya (s.l.)
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Melting of Alpin glaciers from 1979 to 2003
E. Berthier (LEGOS)
The Mont Blanc glacier
by SPOT 5
Glaciers Mass Balance Monitoring
•e.g. :Himalayan glaciers ~ 0,2mm/y (20% cont.melting)
•SPOT/HRS, Accurate but sparse
Available SPOT/HRS data
•SPOT/HRS (120km *600)
•Sparse Coverage
•Weak revisiting period
•Not free of charge…
T 0 + 90 s
T 0
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
•Glaciers Annual Mass Balance = f(snonw_cov. (time, altitude)) (Snow line altitude: Kulkarni et al. 2004, Rabatel et al. 2005)
SRTM NDSI map
A need for an alternative methodology
NDSI Reliable
interanuality
SPOT/VEGETATION (1998 -> 2010)
NDSI altitudinal distribution
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
BMG Chhota Shigri
SPOT/VEGETATION (1998 -> 2010)
NDSI altitudinal distribution
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Glaciers Mass Balance Vs Snowline Altitude
Equation de la droite de régression y = -0,0036x + 14,16 Coefficient de corrélation R2 = 0,9346
-2,00 -1,50 -1,00 -0,50 0,00 0,50
3700 3800 3900 4000 4100 4200 4300 4400
Altitude (en mètre)
Bilan de masse annuel (en mètre d'eau)
BMG = -0,0036*altitude+14,16 R²=0,93
Goal: validate and apply on a larger scale
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Ph.D Thesis of Vanessa Drolon Since Janvier 2013
(thanks to CLS/VITO)
•Improve & validate in the alpine massif
∆ Glaciers Mass=f (snow coverage altitude)
•Move this relationship towards other
regions (Andin, Rockies, high latitudes…)
In situ measurements of Glacier Mass Balance available in the Alps
15
50 glaciers from 1996 to 2008 (Huss et al 2010)
46 glaciers from 1949 to 2010 (World Glaciers Monitoring Service)
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Validation in the alpes
16
Average NDSI (1998-2012) S10 NDSI (1998->2012)
Clouds filtering
(VITO+ CESBIO)
08/07/2013 17
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Available in situ measurements of Alpine Glaciers Mass Balance
50 glaciers from 1996 to 2008 (Huss et al 2010)
46 glaciers de 1949 to 2010 (World Glaciers Monitoring Service)
18
The Albigna glacier 2160-3340 m
(46.3 N, 9.6 E) 5.93 km²
19
-5000 -4000 -3000 -2000 -1000 0 1000 2000 3000 4000
GMB in mm water equivalent
Albigna's winter, summer and annual Mass Balance evolution
Winter Summer Annual
NDSI Time series (9x9 pixels)
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Relationship
Mass balance=F(Altitude) ROI size 15kmx15km
(NDSI * )=0.15
20
y = -0,0040626x + 7,1749 R² = 0,8345
-2500 -2000 -1500 -1000 -500 0 500 1000 1500
0 500 1000 1500 2000 2500
Snow Line Altitude (m)
GMB ( mm water equivalent)
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Seuil R² Equation NDSI
0 0.545499 9.912727 - 0.003083* alt 0,05 0.735725 18.047213 - 0.005291* alt 0,1 0.649704 11.896153 - 0.003414* alt 0,15 0.801422 27.767681 - 0.007504* alt 0,2 0.794974 13.644640 - 0.003631* alt 0,25 0.934395 14.236548 - 0.003662* alt 0,3 0.925652 12.406763 - 0.003131* alt
Seuil R² Equation NDSI
0 0.436324 2.480335 - 0.002171* alt 0,05 0.670659 7.035954 - 0.004299* alt 0,1 0.725319 6.885831 - 0.004043* alt 0,15 0.83446 7.174913 - 0.004063* alt 0,2 0.45393 9.45282 - 0.004892* alt 0,25 0.626545 13.32955 - 0.006368* alt 0,3 0.558737 11.55336 - 0.005379* alt
Equation de la droite de régression y = -0,0036x + 14,16 Coefficient de corrélation R2 = 0,9346
-2,00 -1,50 -1,00 -0,50 0,00 0,50
3700 3800 3900 4000 4100 4200 4300 4400
Altitude (en mètre)
Bilan de masse annuel (en mètre d'eau)
BMG = -0,0041*alti + 7,175 R² = 0,83
-2500 -2000 -1500 -1000 -500 0 500 1000 1500
0 500 1000 1500 2000 2500
Snow Line Altitude (m)
GM B ( mm w at er e qu .)
BMG = -0,0036*alti+14,16 R2=0.93
Chhota Shigri
alt max: 6263m; taille: 16,3 km²;
orientation: Nord
Albigna
alt:2160-3340 m, taille: 4,69,
orientation: Nord
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Short term work ahead (2013)
•Making use of our alpine in situ GMB data base:
- Altitude, size, orientation - Season
- NDSI threshold criteria - Other ?
•Change the S10 compositing criteria for snow (MVC not optimized for snow) … clouds filtering
Probing VEGETATION Conference – Antwerpen 3-4July 2013
1. Apply the validated relationship to other Glaciers in the world (Himalaya, Andes, Rockies, Greenland)
2. Study the VGT/PROBAV overlap until S3 and/or Probav2
NDSI climato
Probing VEGETATION Conference – Antwerpen 3-4July 2013
Work ahead 2014
Probing VEGETATION Conference – Antwerpen 4-5 July 2013
Copyrights E. Berthier