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Michael Lehning

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Related publications (173)

Wind tunnel observations of weak and strong snow saltation dynamics

Michael Lehning, Enrico Paterna, Philip Crivelli

Theoretical considerations suggest that saltation dynamics is dominated by either aerodynamic entrainment or by a combination of ejection and rebound at a given time and location. Calling these two regimes weak and strong saltation, respectively, we have i ...

Amer Geophysical Union2017

Impact of Extreme Land Surface Heterogeneity on Micrometeorology over Spring Snow Cover

Michael Lehning, Sebastian Schlögl

The melting mountain snow cover in spring typically changes from a continuous snow cover to a mosaic of patches of snow and bare ground, inducing an extreme heterogeneity of the land surface. A comprehensive measurement campaign, the Dischma experiment, wa ...

American Meteorological Society2017

Potential contributions of wind power to a stable and highly renewable Swiss power supply

Michael Lehning, Albertus Christiaan Kruyt, Annelen Kahl

Using data from two measurement networks, we analyse the following aspects of wind speeds over Switzerland to assess the possibility of high wind power penetration: spatial correlation, persistent low wind power conditions and the diurnal and seasonal wind ...

Elsevier Sci Ltd2017

Snow farming: Conserving snow over the summer season

Michael Lehning, Thomas Grünewald

2017

Interplay between photovoltaic, wind energy and storage hydropower in a fully renewable Switzerland

Michael Lehning, Albertus Christiaan Kruyt, Stuart John Bartlett, Annelen Kahl, Jérôme François Sylvain Dujardin

As part of its ambitious long term energy strategy, Switzerland plans to phase out nuclear power production and replace most or all of its significant share of national electricity production (40%) by renewables, in particular by photovoltaics (PV) and win ...

Pergamon-Elsevier Science Ltd2017

How do patchy snow covers affect turbulent sensible heat fluxes? – Numerical analysis and experimental findings

Michael Lehning, Sebastian Schlögl

The surface energy balance of a snow cover significantly changes once the snow cover gets patchy. The substantial progress in knowledge about the surface energy balance of patchy snow covers is a mandatory requirement to reduce biases in flux parameterizat ...

2017

Fragmentation of wind-blown snow crystals

Michael Lehning, Enrico Paterna, Francesco Comola, Johan Alexandre Philippe Gaume

Understanding the dynamics driving the transformation of snowfall crystals into blowing snow particles is critical to correctly account for the energy and mass balances in polar and alpine regions. Here we propose a fragmentation theory of fractal snow cry ...

2017

Impact of climate change in Switzerland on socioeconomic snow indices

Michael Lehning, Charles Fierz

Snow is a key element for many socioeconomic activities in mountainous regions. Due to the sensitivity of the snow cover to variations of temperature and precipitation, major changes caused by climate change are expected to happen. We analyze the evolution ...

Springer Verlag2017

Influence of slope-scale snowmelt on catchment response simulated with the Alpine3D model

Tristan Jonas Brauchli, Michael Lehning, Wolf Hendrik Huwald, Ernesto Trujillo Gomez

Snow and hydrological modeling in alpine environments remains challenging because of the complexity of the processes affecting the mass and energy balance. This study examines the influence of snowmelt on the hydrological response of a high-alpine catchmen ...

2017

Energy- and momentum-conserving model of splash entrainment in sand and snow saltation

Michael Lehning, Francesco Comola

Despite being the main sediment entrainment mechanism in aeolian transport, granular splash is still poorly understood. We provide a deeper insight into the dynamics of sand and snow ejection with a stochastic model derived from the energy and momentum con ...

American Geophysical Union2017

Simulating the influence of snow surface processes on soil moisture dynamics and streamflow generation in an alpine catchment

Michael Lehning, Nander Wever, Francesco Comola, Mathias Thierry Pierre Bavay

The assessment of flood risks in alpine, snow-covered catchments requires an understanding of the linkage between the snow cover, soil and discharge in the stream network. Here, we apply the comprehensive, distributed model Alpine3D to investigate the role ...

Copernicus GmbH2017

Wind tunnel experiments: saltation is necessary for wind-packing

Michael Lehning, Christian Gabriel Sommer, Charles Fierz

Wind-packed snow in the form of slabs or crusts is an important part of alpine and polar snow covers. Yet, the formation process of such layers is poorly understood. For example, it remains unclear whether drifting snow is necessary for wind-packing or not ...

International Glaciological Society2017

How do Stability Corrections Perform in the Stable Boundary Layer Over Snow?

Michael Lehning, Wolf Hendrik Huwald, Sebastian Schlögl, Koichi Nishimura

We assess sensible heat-flux parametrizations in stable conditions over snow surfaces by testing and developing stability correction functions for two alpine and two polar test sites. Five turbulence datasets are analyzed with respect to, (a) the validity ...

2017

Wind tunnel experiments: cold-air pooling and atmospheric decoupling above a melting snow patch

Michael Lehning, Enrico Paterna, Philip Crivelli

The longevity of perennial snowfields is not fully understood, but it is known that strong atmospheric stability and thus boundary-layer decoupling limit the amount of (sensible and latent) heat that can be transmitted from the atmosphere to the snow surfa ...

Copernicus GmbH2016

Bodennahe atmosphärische Prozesse und ihre Wirkung auf die hochalpine Schneedecke

Michael Lehning

The atmospheric boundary layer over mountains shows a wide range of special characteristics, especially when mountains are covered with snow. This contribution discusses how cloud dynamics, prferential deposition and snow transport shape the obeserved high ...

2016

Quantifying Particle Numbers and Mass Flux in Drifting Snow

Michael Lehning, Enrico Paterna, Philip Crivelli

We compare two of the most common methods of quantifying mass flux, particle numbers and particle-size distribution for drifting snow events, the snow-particle counter (SPC), a laser-diode-based particle detector, and particle tracking velocimetry based on ...

2016

A new ring‐shaped wind tunnel facility to study wind‐packing of snow

Michael Lehning, Christian Gabriel Sommer, Charles Fierz

A new wind tunnel was designed and built at SLF. The facility is ring-shaped to simulate an infinite fetch. This is important for experiments where the observed processes have a slow time scale (minutes to hours). The wind tunnel was developed to study the ...

University de Genève2016

Sensitivity of Alpine3D modeled snow cover to modifications in DEM resolution, station coverage and meteorological input quantities

Michael Lehning, Sebastian Schlögl, Mathias Thierry Pierre Bavay

This study presents a comprehensive sensitivity and uncertainty assessment of important input parameters on the Alpine3D modeled snow water equivalent (SWE) for two different alpine catchments. Horizontal resolution of the DEM grid, station coverage and se ...

Elsevier2016

Reliable Averages and Risky Extremes – Analysis of spatiotemporal variability in solar irradiance and persistent cloud cover patterns over Switzerland

Michael Lehning, Juliette Ferial Blanchet, Albertus Christiaan Kruyt, Annelen Kahl

With the perspective of Switzerland’s phase-out from nuclear energy, solar energy potential may take an important role for the country’s future in renewable energy. Based on 12 years of satellite-derived, spatially distributed data of daily average cloud f ...

Elsevier2016

StreamFlow 1.0: an extension to the spatially distributed snow model Alpine3D for hydrological modelling and deterministic stream temperature prediction

Tristan Jonas Brauchli, Michael Lehning, Wolf Hendrik Huwald, Aurélien Gallice, Francesco Comola, Mathias Thierry Pierre Bavay

Climate change is expected to strongly impact the hydrological and thermal regimes of Alpine rivers within the coming decades. In this context, the development of hydrological models accounting for the specific dynamics of Alpine catchments appears as one ...

Copernicus Gesellschaft Mbh2016

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