Pirmin Ebner


Last Name

Ebner

First Name

Pirmin

ORCID

0000-0003-1012-5643

Organisational unit

Filters

2014 - 201952020 - 20211
Reset filters

Search Results

Publications 1 - 6 of 6
  • Metamorphism during temperature gradient with undersaturated advective airflow in a snow sample
    Item type: Journal Article
    Ebner, Pirmin; Schneebeli, Martin; Steinfeld, Aldo (2016)
    The Cryosphere
    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.
  • Tomography-based monitoring of isothermal snow metamorphism under advective conditions
    Item type: Journal Article
    Ebner, Pirmin; Schneebeli, Martin; Steinfeld, Aldo (2015)
    The Cryosphere
    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.
  • An instrumented sample holder for time-lapse micro-tomography measurements of snow under advective airflow
    Item type: Journal Article
    Ebner, Pirmin; Grimm, S.A.; Schneebeli, Martin; et al. (2014)
    Geoscientific Instrumentation, Methods and Data Systems
    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.
  • Tomography-based observation of sublimation and snow metamorphism under temperature gradient and advective flow
    Item type: Working Paper
    Ebner, Pirmin; Schneebeli, Martin; Steinfeld, Aldo (2015)
    The Cryosphere Discussions
  • Experimental observation of transient δ18O interaction between snow and advective airflow under various temperature gradient conditions
    Item type: Working Paper
    Ebner, Pirmin; Steen-Larsen, Hans C.; Stenni, Barbara; et al. (2017)
    The Cryosphere Discussions
    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.
  • Vulnerability of ski tourism towards internal climate variability and climate change in the Swiss Alps
    Item type: Journal Article
    Willibald, Fabian; Kotlarski, Sven; Ebner, Pirmin; et al. (2021)
    Science of The Total Environment
    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.
Publications 1 - 6 of 6