09-11 October, Ordino, Andorra http://www.snowandavalanches.ad

1. Simon Gascoin1, Manuel Grizonnet2, Marine Bouchet2, Tristan
Klempka2, Germain Salgues3, Olivier Hagolle1,2
1CESBIO, 2CNES, 3Magellium
Toulouse, France
Two years of high resolution snow cover maps
in the Pyrenees from Sentinel-2 and Landsat-8

2. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
Ramsay 1998

3. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
Ramsay 1998

4. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
Dozier & Marks 1987

5. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
Landsat-5 (Jan 1985)

6. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)

7. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)

8. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
• 2000’s: MODIS
500 m, 1 day day 1
day 2
day 3
day 4
day 5
day 6

9. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
• 2000’s: MODIS
500 m, 1 day
Snow
Cloud
No snow
Gap-filling (cloud removal)

10. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
• 2000’s: MODIS
500 m, 1 day

11. MODIS vs. Landsat
MODIS 500-m, 1 day Landsat-8 30-m, 16 days
t
MODIS
Landsat-8

12. MODIS vs. Landsat
MODIS 500-m, 1 day Landsat-8 30-m, 16 days
t
MODIS
Landsat-8
Sentinel-2

13. Remote sensing of the snow cover area
• 1966 first snow map of
North Hemisphere (NOAA)
190 km, 7 days
• 1980’s: Landsat
30 m, 16 days (at best)
• 2000’s: MODIS
500 m, 1 day
• 2015: Sentinel-2
20 m, 5 days
day 1
day 6
day 11

14. Sentinel-2 TOA
Snow and
cloud masks
Atmospheric
and terrain
correction
Cloud and
cloud shadow
detection
Snow
detection
neigeaNDSI
MIRVIS
MIRVIS
NDSI
Þ>
+
-
=
Sentinel-2 and Landsat-8 snow processor
DEM
Code and doc: http://tully.ups-tlse.fr/grizonnet/let-it-snow

15. Example Sentinel-2 snow map
Snow
No snow
Cloud
Tile 110 km
10 km

16. Example Sentinel-2 snow map
Snow
No snow
Cloud
10 km
Baqueira
1 km

17. Example Sentinel-2 snow map
Snow
No snow
Cloud
10 km
Baqueira
1 km

18. Example Sentinel-2 snow map
Snow
No snow
Cloud
10 km
Snow maps every ~10 days

19. Example Sentinel-2 snow map
10 km
Snow maps every ~10 days
http://www.cesbio.ups-
tlse.fr/multitemp/?p=10274

20. Combining Landsat-8 and Sentinel-2 snow maps
Landsat-8
Sentinel-2

21. Combining Landsat-8 and Sentinel-2 snow maps
Landsat-8
Sentinel-2
Number of images per month

22. Combining Landsat-8 and Sentinel-2 snow maps
1) If both on the same date

23. Combining Landsat-8 and Sentinel-2 snow maps
2) Temporal interpolation by nearest neighbour

24. Combining Landsat-8 and Sentinel-2 snow maps
2) Temporal interpolation by nearest neighbour

25. Combining Landsat-8 and Sentinel-2 snow maps
2) Temporal interpolation by nearest neighbour
Number of snow days

26. Combining Landsat-8 and Sentinel-2 snow maps
Number of snow days in 2015-2016

27. Combining Landsat-8 and Sentinel-2 snow maps
Number of snow days in 2015-2016

28. Combining Landsat-8 and Sentinel-2 snow maps
Number of snow days in 2015-2016
Sentinel-2 + Landsat-8 MODIS Aqua + Terra

29. Combining Landsat-8 and Sentinel-2 snow maps
Number of snow days in 2015-2016
Elevation band (m)

30. Conclusion
Data: http://theia.cnes.fr/Download free Sentinel-2 snow maps
Near real time production coming soon!
And more tiles in the Alps, Spain etc.
Documentation: http://www.cesbio.ups-
tlse.fr/multitemp/?page_id=10748

31. Les Deux Alpes: Summer ski area
Alpe d’Huez
Deux Alpes
SPOT-5 Take5 image time series
http://www.cesbio.ups-
tlse.fr/multitemp/?p=8676