Intercomparison of measurements of bulk snow density and water equivalent of snow cover with snow core samplers: Instrumental bias and variability induced by observers

J. Ignacio López-Moreno*, Leena Leppänen, Bartłomiej 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 Ertaş, Steven R. Fassnacht, Charles Fierz, Christoph Marty

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)3120-3133
Number of pages14
JournalHydrological Processes
Volume34
Issue number14
DOIs
Publication statusPublished - 1 Jul 2020

Bibliographical note

Funding Information:
This research has been taken under the EU‐COST Action HarmoSnow (ES1404: A European network for a harmonised monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction). We also thank to project to HIDROIBERNIEVE (CGL2017‐82216‐R) and to the local organisers of the field campaigns who made possible this work. This work was partially supported within statutory activities No 3841/E‐41/S/2020 of the Ministry of Science and Higher Education of Poland.

Funding Information:
We thank H. L?we and M. Jaggi for the help in analysing the SMP data. This research has been taken under the EU-COST Action HarmoSnow (ES1404: A European network for a harmonised monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction). We also thank to project to HIDROIBERNIEVE (CGL2017-82216-R) and to the local organisers of the field campaigns who made possible this work. This work was partially supported within statutory activities No 3841/E-41/S/2020 of the Ministry of Science and Higher Education of Poland.

Publisher Copyright:
© 2020 John Wiley & Sons Ltd

Other keywords

  • field campaigns
  • snow bulk density
  • snow core sampler
  • SWE
  • uncertainty estimation
  • water equivalent of snow cover

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