Publications related to Hail | EPFL Graph Search

Flash Melting Amorphous Ice

Marcel Drabbels, Ulrich Lorenz, Constantin Richard Krüger, Gabriele Bongiovanni, Nathan Junior Mowry

Water can be vitrified if it is cooled at high rates, which makes it possible to outrun crystallization in so-called no man’s land, a range of deeply supercooled temperatures where water crystallizes rapidly. Here, we study the reverse process in pure wate ...

2024

Wind, Hail, and Climate Extremes: Modelling and Attribution Studies for Environmental Data

Ophélia Mireille Anna Miralles

This thesis presents work at the junction of statistics and climate science. We first provide methodology for use by climate scientists when performing fast event attribution using extreme value theory, and then describe two interdisciplinary projects in c ...

EPFL2023

Use of lidar aerosol extinction and backscatter coefficients to estimate cloud condensation nuclei (CCN) concentrations in the southeast Atlantic

Athanasios Nenes, Feng Xu

Accurately capturing cloud condensation nuclei (CCN) concentrations is key to understanding the aerosol-cloud interactions that continue to feature the highest uncertainty amongst numerous climate forcings. In situ CCN observations are sparse, and most non ...

COPERNICUS GESELLSCHAFT MBH2023

Wind-Topo: Downscaling near-surface wind fields to high-resolution topography in highly complex terrain with deep learning

Michael Lehning, Jérôme François Sylvain Dujardin

Predicting wind flow in highly complex terrain like the Alps is a challenge for all models. When physical processes need to be resolved in a spatially explicit manner, grids with high horizontal resolution of a few hundred meters are often required and dra ...

WILEY2022

Considering snow depositions and transport mechanisms in meteorological analysis of predicting snow loads on buildings

Michael Lehning, Borui Zhang, Qingwen Zhang

The meteorological conditions determine snow evolutions on and around buildings. Those climatic impacts have been independently considered in the current design codes of buildings, namely the wind pressure and the snow load. But snow load estimates are onl ...

ELSEVIER2022

Present and Future of Rainfall in Antarctica

Alexis Berne, Etienne Gabriel Henri Vignon

While most precipitation in Antarctica falls as snow, little is known about liquid precipitation, although it can have ecological and climatic impacts. This study combines meteorological reports at 10 stations with the ERA5 reanalysis to provide a climatol ...

AMER GEOPHYSICAL UNION2021

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

On the drivers of droplet variability in Alpine mixed-phase clouds

Athanasios Nenes, Alexis Berne, Paraskevi Georgakaki, Maxime Hervo, Jörg Wieder

Droplet formation provides a direct microphysical link between aerosols and clouds (liquid or mixed-phase), and its adequate description poses a major challenge for any atmospheric model. Observations are critical for evaluating and constraining the proces ...

Copernicus Publications2021

Biomass burning aerosol as a modulator of the droplet number in the southeast Atlantic region

Athanasios Nenes

The southeastern Atlantic (SEA) and its associated cloud deck, off the west coast of central Africa, is an area where aerosol–cloud interactions can have a strong radiative impact. Seasonally, extensive biomass burning (BB) aerosol plumes from southern Afr ...

Copernicus Publications2020

Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica

Alexis Berne, Etienne Gabriel Henri Vignon

The offshore extent of Antarctic katabatic winds exerts a strong control on the production of sea ice and the formation of polynyas. In this study, we make use of a combination of ground-based remotely sensed and meteorological measurements at Dumont d'Urv ...

2020

Radar measurements of blowing snow off a mountain ridge

Michael Lehning, Wolf Hendrik Huwald, Josué Etienne Gehring, Benjamin Andreas Walter

Modelling and forecasting wind-driven redistribution of snow in mountainous regions with its implications on avalanche danger, mountain hydrology or flood hazard is still a challenging task often lacking in essential details. Measurements of drifting and b ...

2020

Evaluation of global simulations of aerosol particle and cloud condensation nuclei number, with implications for cloud droplet formation

Athanasios Nenes, Julia Schmale, Yang Yang

A total of 16 global chemistry transport models and general circulation models have participated in this study; 14 models have been evaluated with regard to their ability to reproduce the near-surface observed number concentration of aerosol particles and ...

Copernicus Publications2019

Meteorological Aspects of Self-Initiated Upward Lightning at the Santis Tower (Switzerland)

Marcos Rubinstein, Antonio Sunjerga, Farhad Rachidi-Haeri, Mohammad Azadifar, Amirhossein Mostajabi, Nikola Besic, Jacopo Grazioli, Urs Martin Germann

Interest in exploring the meteorological conditions favoring upward lightning from tall man-made structures has grown in recent years, largely due to the worldwide expansion of wind energy. To this end, instrumented towers existing around the world are the ...

2019

The Microphysics of Stratiform Precipitation During OLYMPEX: Compatibility Between Triple-Frequency Radar and Airborne In Situ Observations

Jussi Sakari Leinonen

The link between stratiform precipitation microphysics and multifrequency radar observables is thoroughly investigated by exploiting simultaneous airborne radar and in situ observations collected from two aircraft during the OLYMPEX/RADEX (Olympic Mountain ...

2019

A severe hail storm in complex topography in Switzerland-Observations and processes

Nikola Besic, Urs Martin Germann

This paper studies a damaging hail storm that occurred on 6 June 2015 in the complex topography of Switzerland. The storm persisted for several hours and produced large hail resulting in significant damage. Storms of comparable severity occur on average on ...

ELSEVIER SCIENCE INC2018

Variations in Snow Crystal Riming and ZDR: A Case Analysis

Alexis Berne, Christophe Praz

A case study in terms of variations in differential reflectivity Z(DR) observed at X band and snow crystal riming is presented for a light-snow event that occurred near Greeley, Colorado, on 26-27 November 2015. In the early portion of the event, Z(DR) val ...

2018

The effect of secondary ice production parameterization on the simulation of a cold frontal rainband

Athanasios Nenes

Secondary ice production via processes like rime splintering, frozen droplet shattering, and breakup upon ice hydrometeor collision have been proposed to explain discrepancies between in-cloud ice crystal and ice-nucleating particle numbers. To understand ...

Copernicus Publications2018

Upscaling the evolution of snow microstructure : from 4D image analysis to rigorous models

Quirien Eibhilín Krol

Snow microstructure and its evolution play an important role for various applications of snow physics in cryospheric sciences. The main modes of microstructure evolution in snow are referred to as isothermal and temperature gradient metamorphism. The forme ...

EPFL2017

Suppressed convective rainfall by agricultural expansion in southeastern Burkina Faso

Marc Parlange, Natalie Claire Ceperley, Gabriel George Katul, Theophile Mande, Scott W. Tyler

With the green economy being promoted as a path to sustainable development and food security within the African continent, the influx of agricultural land is proliferating at a rapid pace often replacing natural savannah forests. Where agriculture is prima ...

American Geophysical Union2015