1. Snow Grain Size Workshop Grenoble, France, April 2013
A new shortwave infrared camera approach for snow specific surface area retrieval
Benoit Montpetit, Alain Royer, Alexandre Langlois, Patrick Cliche, Alexandre Roy
Centre d’Applications et de Recherches en Télédétection, Université de Sherbrooke, Québec, Canada
Snow Grain Size Workshop
Grenoble, France, April 2013

2. Introduction Desired instrument attributes
Fast and easy measurement on the field (in situ)
High resolution measurement
Non destructive method
Linked to snow Specific Surface Area (SSA)
High measurement accuracy
High sensitivity to SSA

3. Grain size Greatest extension (Dmax)
Optical diameter (Do) -Related to the volume (V) to surface (S) ratio:
Specific Surface Area (SSA) -Related to optical diameter: -Related to snow albedo measurements:
Kokhanovsky and Zege, 2004, Appl. Opt.

4. Modeled effects of grain size and shape on snow albedo
NIR camera spectral response
SWIR camera spectral response

5. Proposed Method: The SWIR camera
-Xenics Xeva-320 camera InGaAs Array ( µm) 320x256 pixels -Edmund NT Filter
1.295 ± µm
-Lambertian Spectralons targets (0.06, 0.25, 0.59, 0.79 and 0.99)
-Reference Panel

6. Method
Picture Normalization
Albedo Calibration

7. Method
Normalized Gray Scale value

8. Method
NIR photography
SWIR photography

9. InfraRed Integrating Sphere (IRIS) derived from Gallet et al., 2009
InGaAs photodiode
1300nm Laser
Integrating sphere

10. Results
*DUFISSS and CH4 measurements provided by F. Dominé (LGGE)

11. Results

12. Results

13. Results

14. Conclusions Pros: Cons: Grain Size Sensitivity Accuracy
Reproducibility
Spatial resolution (stratigraphy)
2D information
Cons:
Cost
Field Setup

15. Thank you…
Acknowledgments
Polar Continental Shelf Program