On the performance of the snow model Crocus driven by in situ and reanalysis data at Villum Research Station in northeast Greenland

Abstract

Abstract. Reliable and detailed snow data are limited in the Arctic. We aim at overcoming this issue by addressing two questions: (1) Can the reanalysis ERA5 replace limited in situ measurements in high latitudes to drive snow models? (2) Can the Alpine model Crocus simulate reliably Arctic snow depth and stratigraphy? We compare atmospheric in situ measurements and ERA5 reanalysis and evaluate simulated and measured snow depth, density and specific surface area (SSA) in northeast Greenland (October 2014–October 2018). To account for differences between Alpine and Arctic region, we introduce a new parametrisation for the density of new snow.Our results show a good agreement between in situ and ERA5 atmospheric variables except for precipitation, wind speed and direction. ERA5’s resolution is too coarse to resolve the topography in the study area adequately, leading presumably to the detected biases. Nevertheless, measured snow depth agrees better with ERA5 forced simulations than forced with in situ measurements.Crocus can simulate satisfactory the evolution of snow depth, but simulations of SSA and density profiles for both forcings are biased compared to field measurements. Adjusting the new snow density parametrisation leads to improvements in the simulated snow stratigraphy. In conclusion, ERA5 can be used instead of in situ measurements to force snow models but the use of Crocus in the Arctic is affected by limitations likely due to the missing vertical water vapour transport and snow redistribution during strong winds. These limitations strongly affect the accuracy of the vertical profiles of physical snow properties.

Multi-physics ensemble modelling of Arctic tundra snowpack properties

“…Implementation of Arctic modifications into SVS2-Crocus do not produce significant differences in modelled SWE but can affect the simulation of snow depth and bulk density. Wind Effect modifications simulated new snow of a higher density (parameterisations: R21, GW1, GW2) and increased the rate of wind compaction processes (parameterisations: R21F, R21W, R21R) working to increase surface layer density, reduce snow depth and consequential bulk density (Lackner et al, 2022;Royer et al, 2021;Krampe et al, 2021). Without the inclusion of Arctic modifications, default SVS2-Crocus simulated deeper snow depths than Arctic SVS2-Crocus and also overestimated bulk density, due to the dominance of compaction due to overburden weight (Vionnet et al, 2012).…”

“…Using R21, basal layer compaction simulated by default SVS2-Crocus can be reduced without parameterisation of water vapour transport and is a modification that can be easily implemented within operational models. Small improvements in snow density are crucial for permafrost modelling applications and will contribute to an overall improvement in calculations of metamorphism and snowpack temperature gradients for earth system modelling (Barrere et al, 2017;Domine et al, 2019;Krampe et al, 2021). Arctic SVS2-Crocus reduces the RMSE in simulation of SSA over the whole snow profile.…”

“…Detailed multi-layered snowpack models Crocus (Vionnet et al, 2012) and SNOWPACK (Bartelt and Lehning, 2002) suffer from several weaknesses when applied within Arctic environments due to the misrepresentation and lack of consideration for many Arctic processes (Domine et al, 2019;Fourteau et al, 2021;Barrere et al, 2017). Despite showing reasonable agreement in their simulation of snow depth and SWE of Arctic snowpacks (Barrere et al, 2017;Gouttevin et al, 2018;Krinner et al, 2018;Domine et al, 2019;Royer et al, 2021;Krampe et al, 2021;Lackner et al, 2022), both models simulate profiles of increasing density with snow depth because both Crocus and SNOWPACK were originally developed for Alpine applications, where compaction due to the weight of the overlying snow is the dominant process shaping density profiles (Vionnet et al, 2012;Bartelt and Lehning, 2002). Within an Arctic snowpack, strong temperature gradients generate water vapour flux transport that redistributes mass from the bottom to the top of the snowpack, leading to the formation of low-density basal depth hoar layers (Domine et al, 2016b;Fourteau et al, 2021).…”

Snow and meteorological conditions at Villum Research Station, Northeast Greenland: on the adequacy of using atmospheric reanalysis for detailed snow simulations

“…Small inserted panel at left bottom: Sea ice concentration on 15 March 2018 (Maslanik and Stroeve, 2018, National Snow and Data Center, updated yearly). Figure after Krampe et al (2021) in TCD.…”

“…Absolute values below 10 −4 are set to zero. Table after Krampe et al (2021) (Figure 9C). All profiles showed a decrease in SSA from the surface towards the middle part of the snow profile continued by an almost constant course to greater depth.…”