Concept

Brouillard

Publications associées (64)

Representation of Horizontal Transport Processes in Snowmelt Modeling by Applying a Footprint Approach

Michael Lehning, Sebastian Schlögl, Charles Fierz

The energy balance of an alpine snow cover significantly changes once the snow cover gets patchy. The local advection of warm air causes above-average snow ablation rates at the upwind edge of the snow patch. As lateral transport processes are typically no ...

FRONTIERS MEDIA SA2018

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

Wind farm density and harvested power in very large wind farms: A low-order model

Varun Sharma, Marc Calaf Bracons

In this work we create new understanding of wind turbine wakes recovery process as a function of wind farm density using large-eddy simulations of an atmospheric boundary layer diurnal cycle. Simulations are forced with a constant geostrophic wind and a ti ...

Amer Physical Soc2017

A close-ridge small-scale atmospheric flow field and its influence on snow accumulation

Michael Lehning, Franziska Gerber, Sebastian Wilhelm Hoch

The rough, steep, and complex terrain in the alpine environment causes a variety of flow patterns such as blocking, speed-up, or flow separation, which influence precipitation, snow deposition, and ultimately snow distribution on the ground. Cloud-terrain ...

Amer Geophysical Union2017

Polarimetric radar and in situ observations of riming and snowfall microphysics during CLACE 2014

Alexis Berne, Jacopo Grazioli, Luca Panziera

This study investigates the microphysics of winter alpine snowfall occurring in mixed-phase clouds in an inner-Alpine valley during January and February 2014. The available observations include high-resolution polarimetric radar and in situ measurements of ...

Copernicus Publications2015

The relationship between cloud condensation nuclei (CCN) concentration and light extinction of dried particles: Indications of underlying aerosol processes and implications for satellite-based CCN estimates

Athanasios Nenes

We examine the relationship between the number concentration of boundary-layer cloud condensation nuclei (CCN) and light extinction to investigate underlying aerosol processes and satellite-based CCN estimates. For a variety of airborne and ground-based ob ...

Copernicus GmbH2015

Hydrometeor classification from polarimetric radar measurements: a clustering approach

Alexis Berne, Devis Tuia, Jacopo Grazioli

A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt) that can be reliably identified from a large set of pol ...

Copernicus Gesellschaft Mbh2015

CCN properties of organic aerosol collected below and within marine stratocumulus clouds near Monterey, California

Athanasios Nenes

The composition of aerosol from cloud droplets differs from that below cloud. Its implications for the Cloud Condensation Nuclei (CCN) activity are the focus of this study. Water-soluble organic matter from below cloud, and cloud droplet residuals off the ...

MDPI AG2015

Polarimetric weather radar

Jacopo Grazioli

Accurate modelling of liquid, solid and mixed-phase precipitation requires a thorough understanding of phenomena occurring at various spatial and temporal scales. At the smallest scales, precipitation microphysics defines all the processes occurring at the ...

EPFL2015

Validating formulas for the prediction of ascent speed and mass transfer coefficient for liquid oil droplets and gas bubbles under pressure

Jeremy Samuel Arey, Jonas Gros

Several different formulas exist to predict the ascent speed of gas bubbles and oil droplets released in deep waters. Similarly, different formulas are also available to predict the mass transfer coefficient of compounds dissolving into water during ascent ...

2015

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