Student Project: Icefield Reflectance and Albedo

2015 JIRP Student Project: Icefield Reflectance and Albedo

Faculty Experts: Allen Pope

Overview: Surface reflectance (sometimes called albedo, although if you choose this project you will learn why that isn’t strictly accurate) is an important property for understanding how much melt energy a glacier is absorbing. The Icefield reflectance project will use a field spectroradiometer to measure the spectral reflectance of glacier surfaces, studying the spatial and temporal variability of glacier spectral reflectance and albedo. Students will develop questions relating to processes that influence surface reflectance and design data collection strategies accordingly. Some suggestions are given below. The goal of this project is a better understanding of temporal and spatial variability in Icefield reflectance.

Level 1 students are not expected to continue their work beyond the summer field camp unless computations and write up are not completed during summer.

Level 2 students should expect to continue to work on data analysis beyond the summer season, with a more detailed analysis and report turned in near the end of fall semester.

Project breakdown:

Spectral reflectance: This is the basic unit of all subsequent projects. Radiance and irradiance measurements will be collected and students will process these data into reflectance spectra. Students will choose a range of locations and times to understand the spatial and temporal variability in glacier surface reflectance. Levels 1 & 2

Albedo: The next step beyond reflectance spectra, students will incorporate spectral reflectance and irradiance measurements to calculate glacier surface albedo. Students will investigate temporal and spatial variability in albedo resulting from changing illumination conditions and surface properties. Levels 1 & 2

Grain size studies: Students will study temporal and spatial variability in snow grain size by comparing direct observations using a snow card with calculations based on measured reflectance spectra. Level 2 {Possibly level 1}

Impurities: Students will investigate the impact that impurities (dirt/dust/soot) have on spectral reflectance (and albedo). Students can design controlled experiments or locate appropriate natural study sites. Levels 1 & 2

Compare with remote sensing: Understand how your point data scale up to reflectance measurements from airborne and satellite remote sensing measurements. Level 1 students will learn how to directly compare with satellite imagery. Level 2 students will have the opportunity to compare with 2015 observations and design a larger experiment.

Link with energy balance: Join forces with the energy balance modeling project to understand what your albedo measurements mean for surface mass balance. Level 2

Advisor’s Note: I focus on glacial remote sensing, so I focus on pointing the field spectroradiometer at snow and ice. If you’re interested in looking at other reflectance spectra (rocks, algae, or something else), that is something I’m open to, too!

Timeline and Logistics: There are two main constraints on this project: availability of the field spectroradiometer and appropriate weather for data collection. The field spectroradiometer should be available for at least two weeks in mid July, and possibly in early/late July (depending on shipping constraints), but there is nothing we can do about the weather except hope it is good! The field spectroradiometer and controlling laptop need to be charged every night, so fieldwork will be based out of camps, but travel with skis and possibly snowmobiles will be incorporated as the science necessitates it. Locations and frequency of data collection will be determined by student interest. Preliminary analysis will be conducted in camp. Further data collections will then be planned.

References (in approximate order of priority):

1. McArthur, A., 2007. “ASD Collection and Processing Guides,” NERC Field Spectroscopy Facility.

2. Skiles, M., 2015. Snow Optics Lab Protocols.

3. Hendriks, J, and P. Pellikka. “Estimation of Surface Reflectances from Hintereisferner: Spectrometer Measurements and Satellite-Derived Reflectances.” Zeitschrift Für Gletscherkunde Und Glazialgeologie 38, no. 2 (2004): 139–54.

4. Pope, A., and W. G. Rees. “Using in Situ Spectra to Explore Landsat Classification of Glacier Surfaces.” Journal of Applied Earth Observation and Geoinformation 27A (2014): 42–52. doi:10.1016/j.jag.2013.08.007.

5. Gardner, A. S., and M. J. Sharp. “A Review of Snow and Ice Albedo and the Development of a New Physically Based Broadband Albedo Parameterization.” Journal of Geophysical Research-Earth Surface 115 (2010): F01009.

6. Schaepman-Strub, G., et al. “Reflectance Quantities in Optical Remote Sensing - Definitions and Case Studies.” Remote Sensing of Environment 103, no. 1 (2006): 27–42. doi:10.1016/j.rse.2006.03.002.

7. Takeuchi, N. “Temporal and Spatial Variations in Spectral Reflectance and Characteristics of Surface Dust on Gulkana Glacier, Alaska Range.” Journal of Glaciology 55, no. 192 (2009): 701–9.

8.  Greuell, W, C. H. Reijmer, and J. Oerlemans. “Narrowband-to-Broadband Albedo Conversion for Glacier Ice and Snow Based on Aircraft and near-Surface Measurements.” Remote Sensing of Environment 82 (2002): 48–63.

9. Nolin, A, W., and J. Dozier. “A Hyperspectral Method for Remotely Sensing the Grain Size of Snow.” Remote Sensing of Environment 74, no. 2 (2000): 207–16. doi:10.1016/S0034-4257(00)00111-5.

10. Dumont, M. et al. “Contribution of Light-Absorbing Impurities in Snow to Greenland/’s Darkening since 2009.” Nature Geoscience 7, no. 7 (2014): 509–12. doi:10.1038/ngeo2180.

11. Painter, T. H., and J. Dozier. “Measurements of the Hemispherical-Directional Reflectance of Snow at Fine Spectral and Angular Resolution.” Journal of Geophysical Research 109 (2004): 21 PP. doi:200410.1029/2003JD004458.