Preprints
https://doi.org/10.5194/tc-2021-235
https://doi.org/10.5194/tc-2021-235

  01 Sep 2021

01 Sep 2021

Review status: this preprint is currently under review for the journal TC.

GNSS signal-based snow water equivalent determination for different snowpack conditions along a steep elevation gradient

Achille Capelli1,2, Franziska Koch3, Patrick Henkel4, Markus Lamm4, Florian Appel5, Christoph Marty1, and Jürg Schweizer1 Achille Capelli et al.
  • 1WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
  • 2Geophysical Institute, University of Alaska, Fairbanks, USA
  • 3Institute for Hydrology and Water Management, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
  • 4ANavS GmbH, Munich, Germany
  • 5VISTA Remote Sensing in Geosciences GmbH, Munich, Germany

Abstract. Snow water equivalent (SWE) can be measured using low-cost Global Navigation Satellite System (GNSS) sensors with one antenna placed below the snowpack and another one serving as a reference above the snow. The underlying GNSS signal-based algorithm for SWE determination for dry- and wet-snow conditions processes the carrier phases and signal strengths and derives additionally liquid water content (LWC) and snow depth (HS). So far, the algorithm was tested intensively for high-alpine conditions with distinct seasonal accumulation and ablation phases. In general, snow occurrence, snow amount, snow density and LWC can vary considerably with climatic conditions and elevation. Regarding alpine regions, lower elevations mean generally earlier and faster melting, more rain-on-snow events and shallower snowpack. Therefore, we assessed the applicability of the GNSS-based SWE measurement at four stations along a steep elevation gradient (820, 1185, 1510 and 2540 m a.s.l.) in the eastern Swiss Alps during two winter seasons (2018–2020). Reference data of SWE, LWC and HS were collected manually and with additional automated sensors at all locations. The GNSS-derived SWE estimates agreed very well with manual reference measurements along the elevation gradient and the accuracy (RMSE = 34 mm, RMSRE = 11 %) was similar under wet- and dry-snow conditions, although significant differences in snow density and meteorological conditions existed between the locations. The GNSS-derived SWE was more accurate than measured with other automated SWE sensors. However, with the current version of the GNSS algorithm, the determination of daily changes of SWE was found to be less suitable compared to manual measurements or pluviometer recordings and needs further refinement. The values of the GNSS-derived LWC were robust and within the precision of the manual and radar measurements. The additionally derived HS correlated well with the validation data. We conclude that SWE can reliably be determined using low-cost GNSS-sensors under a broad range of climatic conditions and LWC and HS are valuable add-ons.

Achille Capelli et al.

Status: open (until 27 Oct 2021)

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Achille Capelli et al.

Achille Capelli et al.

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Short summary
Snow occurrence, snow amount, snow density and LWC can vary considerably with climatic conditions and elevation. We show that low-cost Global Navigation Satellite System (GNSS) sensors as GPS can be used for measuring reliably the amount of water stored in the snowpack or snow water equivalent (SWE), snow depth and the liquid water content (LWC) under a broad range of climatic conditions met at different elevations in the Swiss Alps.