The seasonal accumulation and melt of snow is a critical cycle that sustains life in snowy, mountainous regions across our planet. The albedo, or reflectance of snow, is a critical component that governs the melt cycles of snow. Snow albedo is implemented in hydrology models to more accurately estimate spring runoff and quantify water resources. Daily and bi-weekly satellite albedo products are offered by MODIS and Landsat respectively, and weather stations provide a sparse network of in-situ measurements for calibration of these satellite data. This project develops and deploys a UAS-based method of measuring the Earth’s albedo to bridge the gap in scale between ground station measurements and satellites, quantify lateral variation in albedo due to terrain and snowpack characteristics, and to observe variation in albedo at different altitudes of measurement.
- Develop and test a UAS-based system for measuring albedo
- Quantify variation in albedo laterally and at different scales
- Compare UAS albedo measurements to Landsat albedo values at the field site
The system is composed of two Kipp and Zonen pyranometers, one facing up and one facing down, mounted on a DJI Matrice 210 quadcopter to detect incoming and reflected broadband shortwave infrared radiation. Mounts for the sensors and a data logger were designed in Autodesk Fusion360 and printed with a fused deposition modeling 3D printer. Test flights using 3D printed dummy sensors were preformed to test the integrity of the mounts and weight distribution on the UAS.
The study area for this project is a mountain meadow at 2600 meters, located just outside of the Yellowstone Club Ski Area in Big Sky, Montana. One flight was preformed on a cloudy, snowy day in April 2019, and another on a bright sunny day in May 2019. During flights, the UAS was able to capture variation in albedo across the landscape. Albedo varied significantly between snow-covered areas and tree-covered areas, and to a minor extent within snow-covered areas. The UAS data from the second flight, coincident with Landsat 7, showed considerable heterogeneity that the satellite did not pick up.
Our results demonstrate the capability of a UAS to measure albedo in a snowy, mountainous environment and offer a means of improving satellite calibrations in remote locations where ground-based measurements are sparse.
This project was featured in a news article in the Montana State University College of Letters and Science newsletter (http://www.montana.edu/lettersandscience/news/18749/msu-earth-sciences-duo-take-snow-measurement-to-new-heights) and results were presented at the 2019 ESIP summer meeting in Tacoma, WA. We are also preparing a manuscript for publication.
March 2019
- Design and fabrication of mounts for sensors and data logger
- Test flights of UAS with 3D printed dummy sensors
April 2019
- First flight in field area, variation in albedo was quantified laterally and at different altitudes.
May 2019
- Second flight in field area, measuring albedo over Landsat 7 grid cells. Variation in UAS albedo measurements within single Landsat 7 grid cells was quantified.
Summer 2019
- Writeup and presentation