Lidar data inversion for cirrus clouds : an approach based on a statistical analysis of in situ microphysical measurements

International audienc

On optical and microphysical characteristics of contrails and cirrus

In situ measurements of light scattering and microphysical characteristics of young and 20 min aged persistent contrails and of frontal cirrus clouds were carried out with the airborne Polar Nephelometer and microphysical PMS instruments. Optical and microphysical properties of contrails at different stages of evolution and of cirrus clouds sampled in ice-supersaturated air masses at ambient temperatures near -60°C are examined. The results show that quasi-spherical ice particles with diameter smaller than 5 µm control the optical properties of the plume shortly after formation. In slightly aged contrails the optical properties are governed by larger nonspherical ice-crystals. Very similar optical properties are observed in frontal cirrus but with a different ice-particle size distribution. The contrail optical and microphysical ice particle data obtained in this study are representative of the visible persistent contrail created by a mid-sized airliner after the wake vortices have decayed

Contribution à la compréhension du changement climatique

National audienceLes premiers modèles climatiques datent des années 1990. C’est aussi à cette date que le premier rapport du GIEC (Groupe d’experts Intergouvernemental sur l’Evolution du Climat) est paru. Dès le 4ème (2007) et le 5ème (2014) rapports, la grande incertitude sur le rôle joué par les nuages et les aérosols par rapport au rayonnement solaire (longueur d’onde ≈ 0,5 µm) a été soulignée. Spécialisé dans les nuages et dans l’atmosphère, c’est naturellement que le Laboratoire de Météorologie Physique (LaMP) choisit d’étudier l’interaction nuage-rayonnement. A l’IUT d’Allier, des sondes de laboratoire et montées sur avion ont été conçues et réalisées afin de quantifier la diffusion de la lumière par les aérosols et les particules nuageuses (eau et/ou glace)

Contribution à la compréhension du changement climatique

National audienceLes premiers modèles climatiques datent des années 1990. C'est aussi à cette date que le premier rapport du GIEC (Groupe d'experts Intergouvernemental sur l'Evolution du Climat) est paru. Dès le 4 ème (2007) et le 5 ème (2014) rapports, la grande incertitude sur le rôle joué par les nuages et les aérosols par rapport au rayonnement solaire (longueur d'onde ≈ 0,5 µm) a été soulignée. Spécialisé dans les nuages et dans l'atmosphère, c'est naturellement que le Laboratoire de Météorologie Physique (LaMP) choisit d'étudier l'interaction nuage-rayonnement. A l'IUT d'Allier, des sondes de laboratoire et montées sur avion ont été conçues et réalisées afin de quantifier la diffusion de la lumière par les aérosols et les particules nuageuses (eau et/ou glace)

The retrieval of cloud microphysical properties using satellite measurements and an in situ database

By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE) held in 1989 over the North Sea

Overview and first analysis of the in situ microphysical measurement dataset collected during the CADDIWA mission

International audienceIn the frame of the Joint Aeolus Tropical Atlantic Campaigns, an airborne field campaign took place in Sal island of Cape-Verde from the 8th to 21st of September 2021, as part of the French CADDIWA mission. During this campaign, the SAFIRE F20 research aircraft equipped with in situ and remote sensing instruments performed nine 3 to 4 hour long flights sampling tropical environment underneath AEOLUS satellite tracks and performing exploration flights within the convective cloud systems of tropical disturbances. In this study, an overview of the available aerosol and cloud in situ dataset is given first, presenting the instrumental and methodological approaches relevant to the collection of data from a set of four instruments: the UHSAS (aerosol size range : 40 – 1000 nm,  Cai et al. 2008), the SPP-300 (aerosol 0.3 – 20 µm, Baumgardner 1992) and the CDP-2 (droplets 2-50 µm, Lance et al. 2010) scattering probes, and the 2D-S imager (10-1280 µm, Lawson et al. 2006). Then a detailed microphysical analysis is conducted on two case studies: a tropical perturbation referred to as Pierre-Henri in this study (unnamed/numbered by NOAA National Hurricane Center (NHC)), sampled during F20 flight #7/8, and the Tropical Storm Rose (# AL172021 according to NOAA NHC) sampled during flights #12/13. The analysis includes a discussion on the main microphysical properties such as Particle Size Distribution (PSD), Ice Water Content (IWC) retrieved at different locations in the cloud convective systems, complemented by 95GHz reflectivity and Doppler vertical velocity measured by the airborne cloud radar RASTA (Delanoe et al. 2013). The data supporting this study is illustrated in the figure below: the vertical velocity (derived from 3 Doppler non colinear measurements of the radar) and PSD time series are given on top of two samples ice crystal images taken by the 2DS imager at different location in the TS Rose. A newly developed image classification algorithm (Jaffeux et al. 2022) is applied to the 2D-S data to derive statistics on the ice particles morphological properties, yielding to a discussion on the microphysical ice growth processes occurring in these systems

Investigation into In Vitro and In Vivo Caenorhabditis elegans Models to Select Cheese Yeasts as Probiotic Candidates for their Preventive Effects against Salmonella Typhimurium

International audienceThe design of multiscale strategies integrating in vitro and in vivo models is necessary for the selection of new probiotics. In this regard, we developed a screening assay based on the investigation of the potential of yeasts from cheese as probiotics against the pathogen Salmonella Typhimurium UPsm1 (ST). Two yeasts isolated from raw-milk cheese (Saccharomyces cerevisiae 16, Sc16; Debaryomyces hansenii 25, Dh25), as well as S. cerevisiae subspecies boulardii (CNCM I-1079, Sb1079), were tested against ST by applying in vitro and in vivo tests. Adherence measurements to Caco-2 and HT29-MTX intestinal cells indicated that the two tested cheese yeasts presented a better adhesion than the probiotic Sb1079 as the control strain. Further, the Dh25 was the cheese yeast most likely to survive in the gastrointestinal tract. What is more, the modulation of the TransEpithelial Electrical Resistance (TEER) of differentiated Caco-2 cell monolayers showed the ability of Dh25 to delay the deleterious effects of ST. The influence of microorganisms on the in vivo model Caenorhabditis elegans was evaluated by measuring the longevity of the worm. This in vivo approach revealed that this yeast increased the worm's lifespan and protected it against ST infection, confirming that this in vivo model can be useful for screening probiotic cheese yeasts