Publications associées à Variations in Snow Crystal Riming and ZDR: A Case Analysis

Highly Hygroscopic Aerosols Facilitate Summer and Early‐Autumn Cloud Formation at Extremely Low Concentrations Over the Central Arctic Ocean

Arctic clouds are sensitive to atmospheric particles since these are sometimes in such low concentrations that clouds cannot always form under supersaturated water vapor conditions. This is especially true in the late summer, when aerosol concentrations ar ...

2024

The molecular scale mechanism of deposition ice nucleation on silver iodide

Mária Lbadaoui-Darvas, Athanasios Nenes, André Welti

Heterogeneous ice nucleation is a ubiquitous process in the natural and built environment. Deposition ice nucleation, i.e. heterogeneous ice nucleation that - according to the traditional view - occurs in a subsaturated water vapor environment and in the a ...

Royal Soc Chemistry2024

Physicochemical characterization and source apportionment of Arctic ice-nucleating particles observed in Ny-Alesund in autumn 2019

Guangyu Li, Athanasios Nenes, Jörg Wieder, Ghislain Gilles Jean-Michel Motos

Ice-nucleating particles (INPs) initiate primary ice formation in Arctic mixed-phase clouds (MPCs), altering cloud radiative properties and modulating precipitation. For atmospheric INPs, the complexity of their spatiotemporal variations, heterogeneous sou ...

Copernicus GmbH2023

Snowfall microphysics: a dual-frequency and Doppler spectral radar perspective

Anne-Claire Marie Billault--Roux

Snowfall is an essential component of the hydrological cycle, as it is involved in most precipitation on Earth, either directly as snow falling to the ground or indirectly as rain melted from snow. At the same time, the ice phase of clouds and precipitatio ...

EPFL2023

On Artificial Intelligence and Manipulation

Marcello Ienca

The increasing diffusion of novel digital and online sociotechnical systems for arational behavioral influence based on Artificial Intelligence (AI), such as social media, microtargeting advertising, and personalized search algorithms, has brought about ne ...

SPRINGER2023

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

Spatio-Temporal Dynamics of Snow on Central Arctic Sea Ice and its Implications

David Nicholas Wagner

This thesis presents a comprehensive investigation of the interaction between precipitation and wind-induced erosion and deposition of snow on Arctic sea ice. The study uses observations from the 2019-2020 MOSAiC expedition and makes use of the 3D snow cov ...

EPFL2023

Deposition freezing, pore condensation freezing and adsorption: three processes, one description?

Mária Lbadaoui-Darvas, Athanasios Nenes

Heterogeneous ice nucleation impacts the hydrological cycle and climate through affecting cloud microphysical state and radiative properties. Despite decades of research, a quantitative description and understanding of heterogeneous ice nucleation remains ...

Copernicus GmbH2023

Ex uno plures: how to construct high-speed movies of collapsing cavitation bubbles from a single image

Mohamed Farhat, Armand Baptiste Sieber, Davide Bernardo Preso

The time-resolved visualization of the dynamics of a cavitation bubble usually requires the use of expensive high-speed cameras, which often provide a limited spatial resolution. In the present study, we propose an alternative to these high-speed imaging t ...

Springer2023

Highly Active Ice‐Nucleating Particles at the Summer North Pole

Julia Schmale

The amount of ice versus supercooled water in clouds is important for their radiative properties and role in climate feedbacks. Hence, knowledge of the concentration of ice-nucleating particles (INPs) is needed. Generally, the concentrations of INPs are fo ...

2022

Wind Transport of Snow Impacts Ka- and Ku-band Radar Signatures on Arctic Sea Ice

Marc Schneebeli Zeugin, David Nicholas Wagner

Wind transport alters the snow topography and microstructure on sea ice through snow redistribution controlled by deposition and erosion. The impact of these processes on radar signatures is poorly understood. Here, we examine the effects of snow redistrib ...

2023

Snowfall and snow accumulation during the MOSAiC winter and spring seasons

Marc Oggier, Michael Lehning, Marc Schneebeli Zeugin, David Nicholas Wagner, Markus Frey

Data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition allowed us to investigate the temporal dynamics of snowfall, snow accumulation and erosion in great detail for almost the whole accumulation season (No ...

COPERNICUS GESELLSCHAFT MBH2022

Detrainment and braking of snow avalanches interacting with forests

Johan Alexandre Philippe Gaume, Xingyue Li, Louis Jean Henri Vedrine

Mountain forests provide natural protection against avalanches. They can both prevent avalanche formation in release zones and reduce avalanche mobility in runout areas. Although the braking effect of forests has been previously explored through global sta ...

COPERNICUS GESELLSCHAFT MBH2022

Identification of snowfall microphysical processes from Eulerian vertical gradients of polarimetric radar variables

Alexis Berne, Josué Etienne Gehring, Noémie Planat, Etienne Gabriel Henri Vignon

Polarimetric radar systems are commonly used to study the microphysics of precipitation. While they offer continuous measurements with a large spatial coverage, retrieving information about the microphysical processes that govern the evolution of snowfall ...

COPERNICUS GESELLSCHAFT MBH2021

Sampling Geometry and Colour

Michalina Wanda Pacholska

In this thesis, we take a signal-processing approach to two research areas outside of the core of the signal processing research: geometry reconstruction and light propagation through non-uniform media. In the first area, we consider new sampling schemes ...

EPFL2021

Radar and ground-level measurements of precipitation collected by the Ecole Polytechnique Federale de Lausanne during the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic winter games

Alexis Berne, Josué Etienne Gehring, Nikola Besic, Alfonso Ferrone, Anne-Claire Marie Billault--Roux

This article describes a 4-month dataset of precipitation and cloud measurements collected during the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic winter games (ICE-POP 2018). This paper aims to describe the data coll ...

COPERNICUS GESELLSCHAFT MBH2021

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

Mixed-Phase Clouds and Precipitation in Southern Ocean Cyclones and Cloud Systems Observed Poleward of 64 degrees S by Ship-Based Cloud Radar and Lidar

Etienne Gabriel Henri Vignon

Mixed-phase clouds (MPCs), composed of both liquid and ice, are prevalent in Southern Ocean cyclones. A characterization of these clouds on fine vertical scales is required in order to understand the microphysical processes within these clouds, and for mod ...

2021

Modelling the small-scale deposition of snow onto structured Arctic sea ice during a MOSAiC storm using snowBedFoam 1.0

Michael Lehning, Marc Schneebeli Zeugin, Océane Hames, Mahdi Jafari, David Nicholas Wagner

The remoteness and extreme conditions of the Arctic make it a very difficult environment to investigate. In these regions, the wind has a substantial effect and redistributes a large part of the snow, which complicates precipitation estimates. Moreover, th ...

2021

A Characterisation of Alpine Mesocyclone Occurrence

Alexis Berne, Marco Gabella, Monika Feldmann, Urs Martin Germann

This work presents a characterisation of mesocyclone occurrence and frequency in the Alpine region, as observed from the Swiss operational radar network; 5 years of radar data are processed with a thunderstorm detection and tracking algorithm and subsequen ...

2021