Compact Probe for In-Situ Optical Snow Grain Size Stratigraphy

1. Compact Probe for In-Situ Optical Snow Grain Size Stratigraphy

2. Snowmelt provides >75% of California’s water. • Mountain snow is the main water source for 60 million Americans. • Snowmelt sustains one billion people globally. • Snowpacks are rapidly changing. http://sos.noaa.gov/datasets/Ocean/snow_ice.html

3. Remote Sensing of Snow • Snow Water Equivalent (SWE) • Radar • SMAP, SCLP, Cryosat II, ERS 1 & 2, Sentinels • Microwave • SCLP, EOS Aqua, Envisat, SMOS, ERS 1 &2

4. Remote Sensing of Snow • SWE algorithms are limited by knowledge of grain size and understanding of the relation between signal and grain size variation.

5. Remote Sensing of Snow • There exists no ground instrument to provide large datasets of grain size stratigraphy. • Armstrong et. al., Annals of Glaciology, 17, 1993, “Snow depths and grain-size relationships with relevance for passive microwave studies”

6. Traditional Grain Size Measurements

7. Traditional Grain Size Measurement http://www.comet.ucar.edu/class/hydromet/09_Oct13_1999/docs/cline/comet_snowhydro/sld038.htm

8. Contact Spectroscopy • Advantages • Less subjective • Repeatable • Faster • Data applicable to remote sensing Painter et al., Journal of Glaciology 2007

9. Spectral Profiler Probe drive tube fiber optic to spectrometer • Send optics down hole • Lateral reflectance spectra • Fiber optic sends signal to surface • No snowpit! • Much faster than pit methods probe carrier body optical camera spectral reflectance probe aluminum sleeve nylon brush

10. Spectral Profiler Probe Hardware optical inspection camera nylon brush In-bore light source spectral reflectance probe

11. probe stowed for transport Field Testing Niwot Ridge, CO Storm Peak Lab, Steamboat Springs, CO

12. Storm Peak Lab Feb 2010 results Paper submitted to Journal of Glaciology

13. New version: Fast, Small, Cheap, Robust • Use discrete optics • Eliminate spectrometer, fiber optic, pre drilling • T measurement • ~1cm dia. Probe • Algorithms for on-site grain size retrieval

14. Ultra-compact probe design

15. Probe tip closeup

16. Discrete Optics Concept Test • Re-processed spectral data using only 2 points

17. Lab test using LED’s Detector + amplifier • Quick cold lab experiment using COTS LED and photodiode/ amplifier shows sensitivity to grain size. LED Snow in pan

18. Discrete Optics Concept Test • availability of LED and laser sources. reflectance Wavelength (nm)

19. NILU collaboration • Collect data from ESA and NASA satellites • Concurrent with probe data • Develop improved algorithms for SWE • Test against ground measurements

20. The Future of Snow Science • All measurements from space • Need better retrieval algorithms • Must understand grain size affect on signals • Need large ground datasets to get there

21. supplemental

22. Acknowledgements • Jennifer Petrzelka • Ty Atkins • Alex Arnsten • Ian McCubbin (Storm Peak Lab) • Gannet Hallar (Storm Peak Lab) • Part of this work was performed at the Jet Propulsion Laboratory/California Institute of Technology under contract from NASA.

23. Compact Probe for In-Situ Optical Snow Grain Size Stratigraphy • NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA • INSTAAR, University of Colorado, Boulder, CO • The Ohio State University, Columbus, OH Daniel Berisford1, Noah Molotch1,2, Thomas H. Painter1, Michael Durand3 Presented at the American Geophysical Union fall meeting, San Francisco, CA. December 13, 2010

24. Contact Spectroscopy • optical equivalent grain size • obtained by integrating absorption feature and comparing to RT model • Painter et al., 2007; Nolin and Dozier, 2000.

25. 2 configurations In-bore light fiber light

26. Niwot Ridge April 2010 results

27. Field Testing spectrometer tarp to block sunlight

28. Field testing

31. Aluminum reflectance spectrum

32. Kapton tape reflectance spectrum