Publications associées à Vortex polaire

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remark ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Polar oceans and sea ice in a changing climate

Julia Schmale, Hélène Paule Angot, Jenny Thomas

Polar oceans and sea ice cover 15% of the Earth’s ocean surface, and the environment is changing rapidly at both poles. Improving knowledge on the interactions between the atmospheric and oceanic realms in the polar regions, a Surface Ocean–Lower Atmospher ...

2023

Synthesis Report on the Environmental Impacts of Polar Research and Logistics in the Polar Regions

Jérôme Chappellaz

Polar sciences are crucial to understand the effects of climate change. 6 out of 9 eco-tipping points identified by the IPCC are situated in the polar regions. Potential rising sea levels, altered weather patterns and changes in sea-currents are all connec ...

2023

Exploring the link between austral stratospheric polar vortex anomalies and surface climate in chemistry-climate models

Nora Bergner

Extreme events in the stratospheric polar vortex can lead to changes in the tropospheric circulation and impact the surface climate on a wide range of timescales. The austral stratospheric vortex shows its largest variability in spring, and a weakened pola ...

Copernicus GmbH2022

Aerobiology over the Southern Ocean – implications for bacterial colonization of Antarctica

Julia Schmale

Parts of the Antarctic are experiencing dramatic ecosystem change due to rapid and record warming, which may weaken biogeographic boundaries and dispersal barriers, increasing the risks of biological invasions. In this study, we collected air samples from ...

2022

Basin-scale gyres and mesoscale eddies in large lakes: A novel procedure for their detection and characterization, assessed in Lake Geneva

David Andrew Barry, Ulrich Lemmin, Seyed Mahmood Hamze Ziabari, Frédéric Charles Soulignac, Mehrshad Foroughan

In large lakes subject to the Coriolis force, basin-scale gyres and mesoscale eddies, i.e. rotating coherent water masses, play a key role in spreading biochemical materials and energy throughout the lake. In order to assess the spatial and temporal extent ...

2022

Emergence of representative signals for sudden stratospheric warmings beyond current predictable lead times

Guillaume Romain Obozinski, Raphaël Gérard Théodore Michel Marie de Deloÿe et Fourcade de Fondeville

Major sudden stratospheric warmings (SSWs) are extreme wintertime circulation events of the Arctic stratosphere that are accompanied by a breakdown of the polar vortex and are considered an important source of predictability of tropospheric weather on subs ...

Copernicus Gesellschaft Mbh2021

Scaling of the translational velocity of vortex rings behind conical objects

Karen Ann J Mulleners, Guillaume de Guyon-Crozier

Ring vortices are efficient at transporting fluid across long distances. They can be found in nature in various ways: they propel squids, inject blood in the heart, and entertain dolphins. These vortices are generally produced by ejecting a volume of fluid ...

2021

On the numerical simulation of a confined cavitating tip leakage vortex under geometrical and operational uncertainties

Mohamed Farhat

The effects of operational and geometrical uncertainties on Tip Leakage Vortex (TLV) characteristics are investigated in the current research. Geometrical uncertainties are comprised of manufacturing tolerances or gradual geometry degradation over the time ...

PERGAMON-ELSEVIER SCIENCE LTD2021

Evolution of the vorticity distribution in vortex rings

Guillaume de Guyon-Crozier

Vortex rings are very efficient at transporting fluid on long distances and can generate large forces, either thrust or drag. These abilities are influenced by the vorticity distribution within the vortex. Previous work on vortices produced by piston-cylin ...

EPFL2021

Meridional and vertical variations of the water vapour isotopic composition in the marine boundary layer over the Atlantic and Southern Ocean

Julia Schmale, Sebastian Johannes Heinz-Josef Landwehr

Stable water isotopologues (SWIs) are useful tracers of moist diabatic processes in the atmospheric water cycle. They provide a framework to analyse moist processes on a range of timescales from large-scale moisture transport to cloud formation, precipitat ...

Copernicus GmbH2020

Ship-based measurements of ice nuclei concentrations over the Arctic, Atlantic, Pacific and Southern oceans

Julia Schmale, André Welti

Ambient concentrations of ice-forming particles measured during ship expeditions are collected and summarised with the aim of determining the spatial distribution and variability in ice nuclei in oceanic regions. The presented data from literature and prev ...

Copernicus Publications2020

Overview: Integrative and Comprehensive Understanding on Polar Environments (iCUPE) – concept and initial results

Julia Schmale, Imad El Haddad, Jakob Boyd Pernov, Jenny Thomas

The role of polar regions is increasing in terms of megatrends such as globalization, new transport routes, demography, and the use of natural resources with consequent effects on regional and transported pollutant concentrations. We set up the ERA-PLANET ...

Copernicus Publications2020

Statistical methods for accounting and understanding ozone trends derived from observations

Eirini Boleti

Emissions of ozone precursors have been regulated in Europe since around 1990 with air quality control measures, which resulted in reductions of nitrogen oxides and volatile organic compounds concentrations. In order to understand how these measures have a ...

EPFL2020

Silicon isotopes in Arctic and sub-Arctic glacial meltwaters: the role of subglacial weathering in the silicon cycle

Tyler Joe Kohler

Glacial environments play an important role in high-latitude marine nutrient cycling, potentially contributing significant fluxes of silicon (Si) to the polar oceans, either as dissolved silicon (DSi) or as dissolvable amorphous silica (ASi). Silicon is a ...

2019

Investigation of subglacial weathering under the Greenland Ice Sheet using silicon isotopes

Tyler Joe Kohler

Subglacial chemical weathering plays a key role in global silicate weathering budgets, contributing to the cycling of silicon (Si) in terrestrial and marine systems and the potential drawdown of carbon dioxide from the atmosphere. Here, we use data from tw ...

2019

RANS computations of a confined cavitating tip-leakage vortex

Mohamed Farhat, Matthieu Dreyer

Cavitating tip-leakage vortices appear in several hydrodynamic flows such as marine propellers or Kaplan turbines. Cavitating computations are a challenging topic since several keys issues are an ongoing work such as the definition of a universal mass sour ...

2018

Imaging magnetic vortex configurations in ferromagnetic nanotubes

Anna Fontcuberta i Morral, Dirk Grundler, Gözde Tütüncüoglu

We image the remnant magnetization configurations of CoFeB and permalloy nanotubes (NTs) using x-ray magnetic circular dichroism photoemission electron microscopy. The images provide direct evidence for flux-closure configurations, including a global vorte ...

American Physical Society2017

Wind tunnel experiments: saltation is necessary for wind-packing

Michael Lehning, Christian Gabriel Sommer, Charles Fierz

Wind-packed snow in the form of slabs or crusts is an important part of alpine and polar snow covers. Yet, the formation process of such layers is poorly understood. For example, it remains unclear whether drifting snow is necessary for wind-packing or not ...

International Glaciological Society2017

Vortex-Breakdown-Induced Particle Capture in Branching Junctions

François Gallaire, Andrea Fani

We show experimentally that a flow-induced, Reynolds number-dependent particle-capture mechanism in branching junctions can be enhanced or eliminated by varying the junction angle. In addition, numerical simulations are used to show that the features respo ...

American Physical Society2016