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Concept

Visibilité

Publications associées (18)

SAFETRANS: a system for 3D visibility estimation and cloud cover detection

Alexandros Papagiannis

The estimation of visibility is of significant importance in aviation safety and forms part of the measurements rou-tinely collected in real time to provide safety guidelines and decisions. Our work concerns the creation and imple-mentation of a lidar-base ...

2023

Australian Bushfires (2019-2020): Aerosol Optical Properties and Radiative Forcing

Romanos Foskinis, Alexandros Papagiannis

In the present study, we present the aerosol optical properties and radiative forcing (RF) of the tropospheric and stratospheric smoke layers, observed by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, during the ...

2022

Pan-Arctic seasonal cycles and long-term trends of aerosol properties from 10 observatories

Julia Schmale, Jakob Boyd Pernov

Even though the Arctic is remote, aerosol properties observed there are strongly influenced by anthropogenic emissions from outside the Arctic. This is particularly true for the so-called Arctic haze season (January through April). In summer (June through ...

Copernicus Publications2022

Identification of blowing snow particles in images from a Multi-Angle Snowflake Camera

Alexis Berne, Christophe Praz, Mathieu Oscar Schaer

A new method to automatically discriminate between hydrometeors and blowing snow particles on MultiAngle Snowflake Camera (MASC) images is introduced. The method uses four selected descriptors related to the image frequency, the number of particles detecte ...

2020

Cloud condensation nuclei activity of six pollenkitts and the influence of their surface activity

Athanasios Nenes

The role of surfactants in governing water interactions of atmospheric aerosols has been a recurring topic in cloud microphysics for more than two decades. Studies of detailed surface thermodynamics are limited by the availability of aerosol samples for ex ...

Copernicus Publications2019

Spatial interpolation of precipitation from multiple rain gauge networks and weather radar data for operational applications in Alpine catchments

Giovanni De Cesare, Bettina Schaefli, Javier García Hernández, Alain Tommy Foehn

Increasing meteorological data availability and quality implies an adaptation of the interpolation methods for data combination. In this paper, we propose a new method to efficiently combine weather radar data with data from two heated rain gauge networks ...

2018

Numerical Experiments of Atmospheric Boundary Layer flows : interplay between distributed drag elements and buoyancy effects

Varun Sharma

Anthropogenic emissions of greenhouse gases due to human activity is causing global warming and inducing climate change. A major implication of global warming is the decreasing ice mass in the polar regions resulting in sea-level rise. It is now known that ...

EPFL2018

Fragmentation of wind-blown snow crystals

Michael Lehning, Johan Alexandre Philippe Gaume, Francesco Comola, Enrico Paterna

Understanding the dynamics driving the transformation of snowfall crystals into blowing snow particles is critical to correctly account for the energy and mass balances in polar and alpine regions. Here we propose a fragmentation theory of fractal snow cry ...

2017

Stochastic modeling of snow transport and hydrologic response in alpine terrain

Francesco Comola

The scientific community has developed a keen interest in the processes driving the hydrologic cycle in alpine regions. The concern mainly stems from the vulnerability of snow-covered environments to the warming temperatures, such that entire ecological an ...

EPFL2017

LEAP: Looking beyond pixels with continuous-space EstimAtion of Point sources

Martin Vetterli, Thierry Blu, Paul Hurley, Matthieu Martin Jean-André Simeoni, Hanjie Pan

Context. Two main classes of imaging algorithms have emerged in radio interferometry: the CLEAN algorithm and its multiple variants, and compressed-sensing inspired methods. They are both discrete in nature, and estimate source locations and intensities on ...

2017

Hawk: Hybrid Datacenter Scheduling

Anne-Marie Kermarrec, Willy Zwaenepoel, Pamela Isabel Delgado Borda, Florin Dinu

This paper addresses the problem of efficient scheduling of large clusters under high load and heterogeneous workloads. A heterogeneous workload typically consists of many short jobs and a small number of large jobs that consume the bulk of the cluster's r ...

USENIX Association2015

Ensemble projections of wildfire activity and carbonaceous aerosol concentrations over the western United States in the mid-21st century

Jed Oliver Kaplan

We estimate future wildfire activity over the western United States during the mid-21st century (2046-2065), based on results from 15 climate models following the A1B scenario. We develop fire prediction models by regressing meteorological variables from t ...

Elsevier2013

Aerosol Transport and Distribution : A Global Modeling Study Constrained by Remote Sensing Observations

The fourth report of the Intergovernmental Panel of Climate Change (IPCC) unambiguously indicates that the climate is changing. Climate change is induced by changes in atmospheric abundances of greenhouse gases and aerosols, solar radiation and land surfac ...

EPFL2012

Sparsity Averaging Reweighted Analysis (SARA): a novel algorithm for radio-interferometric imaging

Yves Wiaux, Jason Douglas McEwen, Rafael Eduardo Carrillo Rangel

We propose a novel algorithm for image reconstruction in radio interferometry. The ill-posed inverse problem associated with the incomplete Fourier sampling identified by the visibility measurements is regularized by the assumption of average signal sparsi ...

OUP2012

Collision-Free Intersection Crossing of Mobile Robots Using Decentralized Navigation Functions on Predefined Paths

Denis Gillet, Laleh Makarem

This paper deals with the coordination of a group of mobile robots at an intersection. It focusses on decentralized navigation functions (DNFs) to achieve efficient traffic control. The main challenge is to define virtual potentials, which are used by dece ...

2011

A satellite- and model-based assessment of the 2003 Russian fires: Impact on the Arctic region

Isabelle Bey, Sylvia Generoso

In this paper, we address the issues of the representation of boreal fires in a global chemistry and transport model (GEOS-Chem) as well as their contribution to the Arctic aerosol optical thickness and black carbon (BC) deposition, with a focus on the 200 ...

2007

Tomography using multiple wavelengths in digital holographic microscopy

Frédéric Montfort

This thesis presents a new tomographic imaging method using multiple wavelengths in digital holographic microscopy. It is based on the addition of several reconstructed wavefronts measured at different wavelengths. The resulting diffraction tomographic vis ...

EPFL2006

Dry and ambient aerosol properties at the Jungfraujoch

Remo Nessler

Atmospheric aerosol is defined as a suspension of solid or liquid particles in air. The major concerns about aerosol particles are their adverse health effects and their role in the Earth's climate system. Atmospheric particles influence the Earth's radiat ...

EPFL2004