Tomography-based monitoring of isothermal snow metamorphism under advective conditions

Time-lapse X-ray microtomography was used to investigate the structural dynamics of isothermal snow metamorphism exposed to an advective airflow. The effect of diffusion and advection across the snow pores on the snow microstructure were analysed in controlled laboratory experiments and possible effects on natural snowpacks discussed. The 3-D digital geometry obtained by tomographic scans was used in direct pore-level numerical simulations to determine the effective permeability. The results showed that isothermal advection with saturated air have no influence on the coarsening rate that is typical for isothermal snow metamorphism. Isothermal snow metamorphism is driven by sublimation deposition caused by the Kelvin effect and is the limiting factor independently of the transport regime in the pores.ISSN:1994-0416ISSN:1994-042

Tomography-based observation of sublimation and snow metamorphism under temperature gradient and advective flow

ISSN:1994-0432ISSN:1994-044

Metamorphism during temperature gradient with undersaturated advective airflow in a snow sample

Snow at or close to the surface commonly undergoes temperature gradient metamorphism under advective flow, which alters its microstructure and physical properties. Time-lapse X-ray microtomography is applied to investigate the structural dynamics of temperature gradient snow metamorphism exposed to an advective airflow in controlled laboratory conditions. Cold saturated air at the inlet was blown into the snow samples and warmed up while flowing across the sample with a temperature gradient of around 50Km−1. Changes of the porous ice structure were observed at mid-height of the snow sample. Sublimation occurred due to the slight undersaturation of the incoming air into the warmer ice matrix. Diffusion of water vapor opposite to the direction of the temperature gradient counteracted the mass transport of advection. Therefore, the total net ice change was negligible leading to a constant porosity profile. However, the strong recrystallization of water molecules in snow may impact its isotopic or chemical content.ISSN:1994-0416ISSN:1994-042

An instrumented sample holder for time-lapse micro-tomography measurements of snow under advective airflow

An instrumented sample holder was developed for time-lapse microtomography of snow samples to enable in situ nondestructive spatial and temporal measurements under controlled advective airflows, temperature gradients, and air humidities. The design was aided by computational fluid dynamics simulations to evaluate the airflow uniformity across the snow sample. Morphological and mass transport properties were evaluated during a 4-day test run. This instrument allows the experimental characterization of metamorphism of snow undergoing structural changes with time.ISSN:2193-0856ISSN:2193-086

Experimental observation of transient δ18O interaction between snow and advective airflow under various temperature gradient conditions

Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect on the snow isotopic composition by airflow through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapor is elucidated. The observed disequilibrium between snow and vapor isotopes led to exchange of isotopes between snow and vapor under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved history is relevant for the interpretation of the snow isotopic composition in the field.ISSN:1994-0432ISSN:1994-044

Vulnerability of ski tourism towards internal climate variability and climate change in the Swiss Alps

Increasing temperatures and snow scarcity pose a serious threat to ski tourism. While the impacts of climate change on ski tourism have been elaborated extensively, little is known so far on the vulnerability of winter tourism towards both internal climate variability and climate change. We use a 50-member single model large ensemble from a regional climate model to drive the physically-based snowpack model SNOWPACK for eight stations across the Swiss Alps to model daily snow depth, incorporating both natural snow conditions and including technical snow production. We make a probabilistic assessment of the vulnerability of ski tourism towards internal climate variability in a future climate by analyzing selected tourism-related snow indicators and find significant overall decrease in snow reliability in the future. Further, we show how the sensitivity towards internal climate variability differs among different tourism-related snow indicators and find that certain indicators are more vulnerable to internal climate variability than others. We show that technical snow production is an appropriate adaptation strategy to tackle risks from climate change and internal climate variability. While technical snow production can drastically reduce uncertainties related to internal climate variability, in low elevations, the technique reaches its limits to counteract global warming by the mid of the century.ISSN:0048-9697ISSN:1879-102

Simulation of snow management in Alpine ski resorts using three different snow models

International audienceSnow management, i. e., snowmaking and grooming, is an integral part of modern ski resort management. While the current snow cover distribution on the slopes is often well known thanks to the usage of advanced monitoring techniques, information about its future evolution is usually lacking. Management-enabled numerical snowpack models driven by meteorological forecasts can help to fill this gap.In the frame of the H2020 project PROSNOW, the snowpack models AMUNDSEN, Crocus, and SNOWPACK/Alpine3D are applied in nine pilot ski resorts across the European Alps for forecasting snow conditions in time scales from days to several months ahead. We present the integration of detailed snowmaking and grooming practices implemented in the three models and show how they can be adapted to individual ski resorts. An ensemble of snow management configurations accounting for a comprehensive set of possible tactical and strategic operational choices is introduced, along with an approach to homogeneously spatialize the results of the three snow models over different areas of the ski resorts. First simulation results are presented for the nine pilot ski resorts in the form of distributed snow water equivalent (SWE) maps along with SWE and snow depth time series for two selected seasons in the past