Preprints
https://doi.org/10.5194/tc-2021-125
https://doi.org/10.5194/tc-2021-125

  30 Apr 2021

30 Apr 2021

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Local-scale uncertainty of seasonal mean and extreme values of in-situ snow depth and snow fall measurements

Moritz Buchmann1,3, Michael Begert2, Stefan Brönnimann3,4, and Christoph Marty1 Moritz Buchmann et al.
  • 1WSL-Institute for Snow- and Avalanche Research SLF, Davos, Switzerland
  • 2Federal Office of Meteorology and Climatology MeteoSwiss, Zürich, Switzerland
  • 3Oeschger Centre for Climate Change Research, University of Bern, Switzerland
  • 4Institute of Geography, University of Bern, Bern, Switzerland

Abstract. Measurements of snow depth and snowfall on the daily scale can vary strongly over short distances. However, it is not clear if there is a seasonal dependence in these variations and how they impact common snow climate indicators based on mean values, as well as estimated return levels of extreme events based on maximum values.

To analyse the impacts of local-scale variations we compiled a unique set of parallel snow measurements from the Swiss Alps consisting of 30 station pairs with up to 77 years of parallel data. Station pairs are mostly located in the same villages (or within 3 km horizontal and 150 m vertical distances).

Investigated snow climate indicators include average snow depth, maximum snow depth, sum of new snow, days with snow on the ground, days with snowfall as well as snow onset and disappearance dates, which are calculated for various seasons (December to February (DFJ), November to April (NDJFMA), and March to April (MA)). We computed relative and absolute error metrics for all these indicators at each station pair to demonstrate the potential uncertainty. We found the largest relative inter-pair differences for all indicators in spring (MA) and the smallest in DJF. Furthermore, there is hardly any difference between DJF and NDJFMA which show median uncertainties of less than 5 % for all indicators. Local-scale uncertainty ranges between less than 24 % (DJF) and less than 43 % (MA) for all indicators and 75 % of all station pairs. Highest (lowest) percentage of station pairs with uncertainty less than 15 % is observed for days with snow on the ground with 90 % (average snow depth, 30 %). Median differences of snow disappearance dates are rather small (three days) and similar to the ones found for snow onset dates (two days). An analysis of potential sunshine duration could not explain the higher uncertainties in spring. To analyse the impact of local-scale variations on the estimation of extreme events, 50-year return levels were quantified for maximum snow depth and maximum 3-day new snow sum, which are often used for prevention measures. The found return levels are within each other’s 95 % confidence intervals for all (but two) station pairs, revealing no striking differences.

The findings serve as an important basis for our understanding of uncertainties of commonly used snow indicators and extremal indices. Knowledge about such uncertainties in combination with break-detection methods is the groundwork in view of any homogenization efforts regarding snow time series.

Moritz Buchmann et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-125', Anonymous Referee #1, 26 May 2021
  • RC2: 'Comment on tc-2021-125', Craig Smith, 28 May 2021
  • RC3: 'Comment on tc-2021-125', Anonymous Referee #3, 06 Jun 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-125', Anonymous Referee #1, 26 May 2021
  • RC2: 'Comment on tc-2021-125', Craig Smith, 28 May 2021
  • RC3: 'Comment on tc-2021-125', Anonymous Referee #3, 06 Jun 2021

Moritz Buchmann et al.

Data sets

Snow climate indicators derived from parallel manual snow measurements Buchmann, Aschauer, Begert, Marty https://doi.org/10.16904/envidat.218

Moritz Buchmann et al.

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Short summary
We investigated the impacts of local-scale variations by analysing snow climate indicators derived from parallel snow measurements. We found the largest relative inter-pair differences for all indicators in spring and the smallest in winter. The findings serve as an important basis for our understanding of uncertainties of commonly used snow indicators and provide, in combination with break-detection methods, the groundwork in view of any homogenization efforts regarding snow time series.