An assessment of sub snow GPS for quantification of snow water equivalent

Abstract

Abstract. Global Navigation Satellite Systems (GNSS) contribute to various Earth observation applications. The present study investigates the potential and limitations of the Global Positioning System (GPS) to estimate in situ water equivalents of the snow cover (snow water equivalent, SWE) by using buried GPS antennas. GPS derived SWE is estimated over three seasons (2015/16 -2017/18) at a high Alpine test site in Switzerland. Results are validated against state of the art reference sensors: snow scale, snow pillow, and manual observations. SWE is estimated with a high correspondence to the reference sensors for 5 all three seasons. Results agree with a median relative bias below 10 % and are highly correlated to the mean of the three reference sensors. The sensitivity of the SWE quantification is assessed for different GPS ambiguity resolution techniques, as the results strongly depend on the GPS processing.

Retrieval of Snow Water Equivalent, Liquid Water Content, and Snow Height of Dry and Wet Snow by Combining GPS Signal Attenuation and Time Delay

“…By exploiting the GNSS carrier phases using low‐cost sensors, Henkel et al () derived SWE for dry‐snow conditions. Steiner et al () confirmed the applicability applying a similar approach but using geodetic sensors and calculated daily SWE values for an entire winter season applying different ambiguity resolution strategies and using widelane combinations. SWE values were represented fairly well; however, no distinction between dry‐ and wet‐snow conditions was made.…”

“…In general, the study site Weissfluhjoch is ideal for GPS signal reception in mountainous regions. The GPS satellite coverage is very high due to almost unobscured sky visibility above 10° elevation in the southern directions and slightly above approximately 15 to 20° elevation in all other directions (Steiner, Meindl, Fierz, & Geiger, ). For this reason and because signals from very low elevation angles are quite weak and prone to multipath effects, which means that the reception of a specific GPS signals is influenced by multiple signal paths due to reflections on the Earth's surface, we applied a 15° elevation mask for all azimuth directions.…”

Multi-decadal observations in the Alps reveal less and wetter snow, with increasing variability

“…During the last decades data from these different monitoring programs have been used for the development of the national snow load code (Martinec, 1975), forest-snow interactions (López-Moreno and Stähli, 2008), international snow model intercomparisons (Rutter et al, 2009), microwave backscattering of snow (Werner et al, 2010), snow climate projections (Schmucki et al, 2014), international solid precipitation inter-comparisons (Smith et al, 2017), snow model development (Wever et al, 2015;Fiddes et al, 2019), snow density parametrizations (Jonas et al, 2009;Helfricht et al, 2018;Guidicelli et al, 2021), glacier massbalance investigations (Huss et al, 2021) and sensor tests (Stähli et al, 2004;Steiner et al, 2019;Capelli et al, 2022). However, each of these studies has always only used data from one of these individual monitoring programs, and a joint analysis is still missing, possibly due to the different temporal resolution of the measurements.…”