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Publications associées (22)

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Influence of sun cups on surface albedo of wet Alpine snowpack

Michael Lehning, Loïc Marcel Louis Brouet

In high elevation Alpine areas, characterised by high snow accumulation and radiation-driven melt processes, the formation of peculiar ablation features called sun cups can be observed. Sun cups likely influence the energy and mass balance of the wet snowp ...

2024

The role of secondary ice production in mixed-phase clouds

Paraskevi Georgakaki

Clouds are omnipresent in the Earth's atmosphere. Their phase composition significantly modulates their interaction with solar and terrestrial radiation, as well as precipitation formation. Particularly for clouds containing both phases, known as mixed-pha ...

EPFL2023

Modelling the coupled mercury-halogen-ozone cycle in the central Arctic during spring

Julia Schmale, Ivo Fabio Beck, Hélène Paule Angot

Near-surface mercury and ozone depletion events occur in the lowest part of the atmosphere during Arctic spring. Mercury depletion is the first step in a process that transforms long-lived elemental mercury to more reactive forms within the Arctic that are ...

2023

An analytical approximation of urban heat and dry islands and their impact on convection triggering

Gabriele Manoli

It is well known that cities increase air and surface temperatures compared to their rural sur-roundings, the so-called urban heat island (UHI) effect. However, the associated changes in at-mospheric humidity (also known as urban dry island, UDI) and conve ...

ELSEVIER2022

Modeling Extreme Warm-Air Advection in the Arctic During Summer: The Effect of Mid-Latitude Pollution Inflow on Cloud Properties

Georgia Sotiropoulou

Usually the Arctic is relatively free of anthropogenic influence in summer, which means that particles from natural sources can be the most significant nuclei for cloud droplets. However, this is not the case during anomalously warm-air intrusions when the ...

2021

Leveraging meteorological radars to investigate the influence of atmospheric dynamics on snowfall microphysics

Josué Etienne Gehring

Precipitation is the result of a chain of meteorological processes ranging from the large- to the micro-scale. While the transport of moisture and lifting mechanisms leading to cloud formation are mostly governed by dynamical processes, the formation and g ...

EPFL2021

Augmenting the performance of impoverished sensor networks using machine learning and time reversal: Application to lightning nowcasting and location

Amirhossein Mostajabi

Lightning is formed in the atmosphere through the combination of intricate dynamic and microphysical processes. Mainly due to this complexity, attempts to solve the important problem of lightning prediction have generally failed to yield accurate results. ...

EPFL2021

Intercomparison of Large-Eddy Simulations of the Antarctic Boundary Layer for Very Stable Stratification

Etienne Gabriel Henri Vignon, John Edward Harper

In polar regions, where the boundary layer is often stably stratified, atmospheric models produce large biases depending on the boundary-layer parametrizations and the parametrization of the exchange of energy at the surface. This model intercomparison foc ...

2020

From observations to 3D forecasts: Data assimilation for high resolution lakes monitoring

Theo Baracchini

Lake mesoscale processes have no secrets for artists, they have some for scientists and policy-makers. In the introduction to this dissertation, we saw that poets and painters depict the lake with rich variability. This vision conflicts with conventional a ...

EPFL2019

Artificial neural networks can be used for Ambrosia pollen emission parameterization in COSMO-ART

Charlotte Marie Bürki

The emission parameterization is a crucial part of numerical pollen dispersion models. This paper shows that Artificial Neural Networks (ANNs) can substantially improve the performance of the Ambrosia pollen emission in numerical pollen dispersion models s ...

Elsevier2019

Multi-scale modeling of the urban meteorology: Integration of a new canopy model in the WRF model

Dasaraden Mauree, Alain Clappier

Urban parametrizations have been recently developed and integrated in mesoscale meteorological models for a better reproduction of urban heat islands and to compute building energy consumption. The objective of the present study is to evaluate the value of ...

2018

Correction of CCI cloud data over the Swiss Alps using ground-based radiation measurements

Alexis Berne

The validation of long-term cloud data sets retrieved from satellites is challenging due to their worldwide coverage going back as far as the 1980s. A trustworthy reference cannot be found easily at every location and every time. Mountainous regions presen ...

Copernicus GmbH2018

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

Michael Lehning, Wolf Hendrik Huwald, Sebastian Schlögl

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

Implementation and Performance Analysis of the Lightning Potential Index as a Forecasting Tool

Farhad Rachidi-Haeri, Aleksandr Smorgonskii

Severe weather events are responsible for hundreds of fatalities and millions of euros of damage every year in the Mediterranean basin. Lightning activity is a characteristic phenomenon of severe weather and often accompanies torrential rainfall, which und ...

Ieee2016

LCA as key factor for implementation of inertia in a low carbon performance driven design: the case of the smart living building in Fribourg, Switzerland

Marilyne Andersen, Emmanuel Rey, Thomas Bernard Paul Jusselme, Endrit Hoxha, Arianna Brambilla

The building sector is known as a major contributor to greenhouse gas (GHG) emissions and energy consumption. These impacts are commonly evaluated by life cycle assessment (LCA), which assess the potential impacts of a building from the construction to the ...

2016

Evaluating snow models with varying process representations for hydrological applications

Nander Wever

Much effort has been invested in developing snow models over several decades, resulting in a wide variety of empirical and physically based snow models. For the most part, these models are built on similar principles. The greatest differences are found in ...

American Geophysical Union2015

Experimental Quantification of the Variability of the Raindrop Size Distribution at Small Scales

Joël Jaffrain

Reliable quantitative precipitation estimation is crucial to better understand and eventually prevent water-related natural hazards (floods, landslides, avalanches, ...). Because rainfall is highly variable in time and space, precipitation monitoring and f ...

EPFL2012

Mapping frequencies of icing on structures in Switzerland

Michael Lehning, Thomas Grünewald, Walter Steinkogler

Icing of structures is a problem for wind energy production in cold regions and makes careful planning of new projects essential. This study presents and evaluates a method to create a map showing the frequency of meteorological icing in Switzerland. Icing ...

2012

Improving Alpine Flood Prediction through Hydrological Process Characterization and Uncertainty Analysis

Cara Christine Tobin

Among the many challenges of Alpine flood prediction is describing complex, meteo-hydrological processes in a simplified, robust manner that can be easily integrated into operational forecasting. In this dissertation, improved methods to characterize these ...

EPFL2012

Recent warming in Greenland in a long-term instrumental (1881-2012) climatic context: I. Evaluation of surface air temperature records

Konrad Steffen

We present an updated analysis of monthly means of daily mean, minimum and maximum surface air temperature (SAT) data from Greenland coastal weather stations and from a long-running site on the Greenland ice sheet, and analyse these data for evidence of cl ...

IOP Publishing2012