Publications related to Squall line

Nitrogen oxides in the free troposphere: implications for tropospheric oxidants and the interpretation of satellite NO2 measurements

Satellite-based retrievals of tropospheric NO(2)columns are widely used to infer NOx (equivalent to NO + NO2) emissions. These retrievals rely on model information for the vertical distribution of NO2. The free tropospheric background above 2 km is particu ...

Copernicus GmbH2023

Supercell Thunderstorms in the Alpine Region - From Weather Radar Observations to Idealized Modeling

Monika Feldmann

The high-impact nature and increasing occurrence of severe weather phenomena pushes forward research on their occurrence and improving our understanding thereof. Supercell thunderstorms are the focus of much severe convective research, as they represent on ...

EPFL2023

Convection of snow: when and why does it happen?

Michael Lehning, Mahdi Jafari

Convection of water vapor in snowpacks is supposed to have a major impact on snow density and microstructure profiles with strong implications for the thermal regime and snow stability. However, the process has never been directly measured and only recentl ...

FRONTIERS MEDIA SA2023

Spatiotemporal modelling of extreme wildfires and severe thunderstorm environments

Jonathan Koh Boon Han

Environmental extreme events can have devastating impacts on society when they interact with vulnerable human and natural systems. Such events can result from natural causes, like phenomena related to the El Ni~no-Southern Oscillation or decadal/multi-dec ...

EPFL2022

LMDZ6A: The Atmospheric Component of the IPSL Climate Model With Improved and Better Tuned Physics

Etienne Gabriel Henri Vignon

This study presents the version of the LMDZ global atmospheric model used as the atmospheric component of the Institut Pierre Simon Laplace coupled model (IPSL-CM6A-LR) to contribute to the 6th phase of the international Coupled Model Intercomparison Proje ...

2020

Analysis of the lightning production of convective cells

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

This paper presents an analysis of the lightningproduction of convective cells. The cells were detected by the MeteoSwiss Thunderstorms Radar Tracking (TRT) algorithm in the course of a lightning measurement campaign thattook place in the summer of 2017 in ...

2019

Convection in Lakes

Alfred Johny Wüest, Damien Bouffard

Lakes and other confined water bodies are not exposed to tides, and their wind forcing is usually much weaker compared to ocean basins and estuaries. Hence, convective processes are often the dominant drivers for shaping mixing and stratification structure ...

2019

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

Effects of regional and local atmospheric dynamics on the aerosol and CCN load over Athens

Athanasios Nenes

Aerosol and cloud condensate nuclei (CCN) measurements in the area of Athens during HyGRA-CD campaign (May–June 2014) identified a significant diversity in particle properties. In this study we select two distinct cases in terms of meteorology and air mass ...

Elsevier2018

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

Lightning Potential Index performances in multimicrophysical cloud-resolving simulations of a back-building mesoscale convective system: The Genoa 2014 event

Farhad Rachidi-Haeri, Martina Lagasio

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

Amer Geophysical Union2017

Invariance of the Double-Moment Normalized Raindrop Size Distribution through 3D Spatial Displacement in Stratiform Rain

Alexis Berne, Timothy Hugh Raupach

Double-moment normalization of the drop size distribution (DSD) summarizes the DSD in a compact way, using two of its statistical moments and a "generic'' double-moment normalized DSD function. Results are presented of an investigation into the invariance ...

Amer Meteorological Soc2017

Distributed snow and rock temperature modelling in steep rock walls using Alpine3D

Michael Lehning, Nander Wever, Mathias Thierry Pierre Bavay

In this study we modelled the influence of the spatially and temporally heterogeneous snow cover on the surface energy balance and thus on rock temperatures in two rugged, steep rock walls on the Gemsstock ridge in the central Swiss Alps. The heterogeneous ...

Copernicus GmbH2017

Development of a methodology for extreme flood estimations in alpine catchments for the verification of dam safety

Fränz Zeimetz

In the context of dam safety, reliable safety flood estimation methods are necessary to guarantee a sufficiently designed spillway capacity. Todayâ s state of the art allows to approach this topic under different angles. Statistical extrapolations are com ...

EPFL2017

The effects of radiation on ablative heat shields during atmospheric entry

Nikhil Banerji

Spacecraft employ composite materials as Thermal Protection Systems (TPS) to survive entering a planetary atmosphere at hypersonic speeds. Under intense convective and radiative heating from the surrounding shock layer, these composites decompose and erode ...

EPFL2017

Attenuation of wind-induced pressure perturbations in alpine snow

Wolf Hendrik Huwald, Marc Parlange, Chad Higgins

Windpumping has been identified as a process that could potentially enhance sublimation of surface snow at high forcing frequency and spawn air movement deeper in firn at lower frequencies. We performed an experiment to examine the relationship between hig ...

International Glaciological Society2016

Mitigation of Wind-Induced Vibrations in Long-Span Bridges using a Distributed Flap System

Klara Maria Boberg

Since the collapse of the Tacoma Narrows Bridge more than 70 years ago suppressing wind-induced instabilities has been a key aspect of the design of long-span bridges. The intensive experimental and theoretical research in wind engineering allowed research ...

EPFL2016

Atmospheric Flow Development and Associated Changes in Turbulent Sensible Heat Flux over a Patchy Mountain Snow Cover

Michael Lehning

In this study, the small-scale boundary layer dynamics and the energy balance over a fractional snow cover are numerically investigated. The atmospheric boundary layer flows over a patchy snow cover were calculated with an atmospheric model (Advanced Regio ...

Amer Meteorological Soc2015