Measuring prairie snow water equivalent with combined UAV-borne gamma spectrometry and lidar

• Published in: The Cryosphere
• Main Authors: Harder, Philip, Helgason, Warren, Pomeroy, John W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2024
• Subjects: Prairie; Snow; The Cryosphere
• Online Access: https://hdl.handle.net/10388/15865; https://doi.org/10.5194/tc-18-3277-2024

Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors Canada First Research Excellence Fund (grant no. CFREF-2015-00010), the Natural Sciences and Engineering Research Council of Canada (grant no. CRC-2016-00144), the Western Economic Diversification Canada (grant no. 000014400), and the Canada Foundation for Innovation (grant no. 37227) Peer Reviewed Despite decades of effort, there remains an inability to measure snow water equivalent (SWE) at high spatial resolutions using remote sensing. Passive gamma ray spectrometry is one of the only well-established methods to reliably remotely sense SWE, but airborne applications to date have been limited to observing kilometre-scale areal averages. Noting the increasing capabilities of unoccupied aerial vehicles (UAVs) and miniaturization of passive gamma ray spectrometers, this study tested the ability of a UAV-borne gamma spectrometer and concomitant UAV-borne lidar to quantify the spatial variability of SWE at high spatial resolutions. Gamma and lidar observations from a UAV (UAV-gamma and UAV-lidar) were collected over two seasons from shallow, wind-blown, prairie snowpacks in Saskatchewan, Canada, with validation data collected from manual snow depth and density observations. A fine-resolution (0.25 m) reference dataset of SWE, to test UAV-gamma methods, was developed from UAV-lidar snow depth and snow survey snow density observations. The ability of UAV-gamma to resolve the areal average and spatial variability of SWE was promising with appropriate flight characteristics. Survey flights flown at a velocity of 5 m s−1, altitude of 15 m, and line spacing of 15 m were unable to capture the average or spatial variability of SWE within the uncertainty of the reference dataset. Slower, lower, ...