Intercomparison of measurements of bulk snow density and water equivalent of snow cover with snow core samplers: Instrumental bias and variability induced by observers |
| |
| Authors: | J Ignacio López-Moreno Leena Leppänen Bart?omiej Luks Ladislav Holko Ghislain Picard Alba Sanmiguel-Vallelado Esteban Alonso-González David C Finger Ali N Arslan Katalin Gillemot Aynur Sensoy Arda Sorman M Cansaran Erta? Steven R Fassnacht Charles Fierz Christoph Marty |
| |
| Institution: | 1. Pyrenean Institute of Ecology, CSIC. Department of Environmental Processes and Global Change, Zaragoza, Spain;2. Finnish Meteorological Institute, Arctic Research Center, Sodankylä, Finland;3. Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland;4. Institute of Hydrology, Slovak Academy of Sciences, Bratislava, Slovakia;5. UGA, CNRS, Institut des Géosciences de l'Environnement (IGE), Grenoble, France;6. Sustainability Institute and Forum (SIF), School of Science and Engineering, Reykjavik University, Reykjavik, Iceland;7. ENGAGE - Geomorphological Systems and Risk Research, Department of Geography and Regional Research, University of Vienna, Vienna, Austria;8. Eskisehir Technical University, Faculty of Engineering, Department of Civil Engineering, Eskisehir, Turkey;9. Colorado State University, Ecosytem Science and Sustainability – Watershed Science, Fort Collins, Colorado, USA;10. WSL Institute for Snow and Avalanche Research SLF, Snow and Permafrost, Davos, Switzerland |
| |
| Abstract: | Manually collected snow data are often considered as ground truth for many applications such as climatological or hydrological studies. However, there are many sources of uncertainty that are not quantified in detail. For the determination of water equivalent of snow cover (SWE), different snow core samplers and scales are used, but they are all based on the same measurement principle. We conducted two field campaigns with 9 samplers commonly used in observational measurements and research in Europe and northern America to better quantify uncertainties when measuring depth, density and SWE with core samplers. During the first campaign, as a first approach to distinguish snow variability measured at the plot and at the point scale, repeated measurements were taken along two 20 m long snow pits. The results revealed a much higher variability of SWE at the plot scale (resulting from both natural variability and instrumental bias) compared to repeated measurements at the same spot (resulting mostly from error induced by observers or very small scale variability of snow depth). The exceptionally homogeneous snowpack found in the second campaign permitted to almost neglect the natural variability of the snowpack properties and focus on the separation between instrumental bias and error induced by observers. Reported uncertainties refer to a shallow, homogeneous tundra-taiga snowpack less than 1 m deep (loose, mostly recrystallised snow and no wind impact). Under such measurement conditions, the uncertainty in bulk snow density estimation is about 5% for an individual instrument and is close to 10% among different instruments. Results confirmed that instrumental bias exceeded both the natural variability and the error induced by observers, even in the case when observers were not familiar with a given snow core sampler. |
| |
| Keywords: | field campaigns snow bulk density snow core sampler SWE uncertainty estimation water equivalent of snow cover |
|
|
