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Concept

Nuage nacré

Publications associées (20)

Simulations of primary and secondary ice production during an Arctic mixed-phase cloud case from the Ny-Ålesund Aerosol Cloud Experiment (NASCENT) campaign

Georgia Sotiropoulou, Paraskevi Georgakaki

The representation of Arctic clouds and their phase distributions, i.e., the amount of ice and supercooled water, influences predictions of future Arctic warming. Therefore, it is essential that cloud phase is correctly captured by models in order to accur ...

Copernicus GmbH2024

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

Julia Schmale, Andrea Baccarini

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

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

Physical and Chemical Properties of Cloud Droplet Residuals and Aerosol Particles During the Arctic Ocean 2018 Expedition

Julia Schmale, Andrea Baccarini, Lubna Dada

Detailed knowledge of the physical and chemical properties and sources of particles that form clouds is especially important in pristine areas like the Arctic, where particle concentrations are often low and observations are sparse. Here, we present in sit ...

2022

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

Secondary ice production in summer clouds over the Antarctic coast: an underappreciated process in atmospheric models

Alexis Berne, Athanasios Nenes, Etienne Gabriel Henri Vignon, Georgia Sotiropoulou

The correct representation of Antarctic clouds in atmospheric models is crucial for accurate projections of the future Antarctic climate. This is particularly true for summer clouds which play a critical role in the surface melting of the ice shelves in th ...

European Geosciences Union2021

Ice multiplication from ice-ice collisions in the high Arctic: sensitivity to ice habit, rimed fraction, ice type and uncertainties in the numerical description of the process

Athanasios Nenes, Georgia Sotiropoulou

Atmospheric models often fail to correctly reproduce the microphysical structure of Arctic mixed-phase clouds and underpredict ice water content even when the simulations are constrained by observed levels of ice nucleating particles. In this study we inve ...

Copernicus GmbH2021

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

Athanasios Nenes, Alexis Berne, Paraskevi Georgakaki

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

Changing atmospheric acidity as a modulator of nutrient deposition and ocean biogeochemistry

Athanasios Nenes

Anthropogenic emissions to the atmosphere have increased the flux of nutrients, especially nitrogen, to the ocean, but they have also altered the acidity of aerosol, cloud water, and precipitation over much of the marine atmosphere. For nitrogen, acidity-d ...

AMER ASSOC ADVANCEMENT SCIENCE2021

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

Properties of Arctic liquid and mixed-phase clouds from shipborne Cloudnet observations during ACSE 2014

Georgia Sotiropoulou

This study presents Cloudnet retrievals of Arctic clouds from measurements conducted during a 3-month research expedition along the Siberian shelf during summer and autumn 2014. During autumn, we find a strong reduction in the occurrence of liquid clouds a ...

Copernicus GmbH2020

The acidity of atmospheric particles and clouds

Athanasios Nenes

Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semivolatile gases such as HNO3, NH3, HCl, and orga ...

Copernicus Publications2020

Constraining the Twomey effect from satellite observations: issues and perspectives

Athanasios Nenes

The Twomey effect describes the radiative forcing associated with a change in cloud albedo due to an increase in anthropogenic aerosol emissions. It is driven by the perturbation in cloud droplet number concentration (Delta N-d, (ant)) in liquid-water clou ...

Copernicus GmbH2020

Improved Representation of Clouds in the Atmospheric Component LMDZ6A of the IPSL-CM6A Earth System Model

Etienne Gabriel Henri Vignon

The cloud parameterizations of the LMDZ6A climate model (the atmospheric component of the IPSL-CM6 Earth system model) are entirely described, and the global cloud distribution and cloud radiative effects are evaluated against the CALIPSO-CloudSat and CERE ...

2020

Indoor air treatment of refrigerated food chambers with synergetic association between cold plasma and photocatalysis: Process performance and photocatalytic poisoning

Sami Rtimi

The purpose of this study is to evaluate the efficiency of non-thermal plasma (NTP) and heterogeneous photocatalytic processes for indoor air treatment of refrigerated food chambers. Propionic acid and benzene were chosen as target pollutants to simulate o ...

ELSEVIER SCIENCE SA2020

Meteorological conditions during self-initiated upward lightning at the Säntis tower (Switzerland)

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

Meteorological conditions favoring the initiation of upward lightning from tall structures have been only poorly investigated so far. In addition to the scientific interest in this subject, it has practical applications to risk assessment for lightning occ ...

2019

Trends of surface maximum ozone concentrations in Switzerland based on meteorological adjustment for the period 1990-2014

Satoshi Takahama, Eirini Boleti

We investigate the temporal trends of peak ozone in Switzerland for the 1990-2014 time period. The meteorological conditions have a large influence on ozone formation and drive a large part of the variability in ozone observations. Therefore, the influence ...

Elsevier2019

Retrieval of ice-nucleating particle concentrations from lidar observations and comparison with UAV in situ measurements

Athanasios Nenes

Aerosols that are efficient ice-nucleating particles (INPs) are crucial for the formation of cloud ice via heterogeneous nucleation in the atmosphere. The distribution of INPs on a large spatial scale and as a function of height determines their impact on ...

Copernicus Publications2019

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

On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes - Part 2: The effects of the El Nino/Southern Oscillation, volcanic eruptions and contributions of atmospheric dynamics and chemistry to long-term total ozone changes

Anthony Christopher Davison, Linda Frossard

We present the first spatial analysis of "fingerprints" of the El Nino/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichon and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and me ...

Copernicus Publications2013