L'invention concerne un ensemble detecteur de fibres (210, 310, 410, 510) comportant : (i) un... more L'invention concerne un ensemble detecteur de fibres (210, 310, 410, 510) comportant : (i) un corps de chambre a diffusion ; (ii) un moyen permettant d'attirer des particules au travers dudit corps de chambre sous la forme d'un flux de particules, ledit moyen etant adapte de sorte que les particules ont tendance a avancer en une seule file, l'axe longitudinal des particules de forme allongee etant sensiblement aligne sur la direction du flux ; (iii) un moyen permettant d'illuminer le flux de particules (212, 312, 412, 413, 512, 513) a l'interieur du corps de chambre ; (iv) un detecteur optique (236, 336, 338, 436, 536, 538) adapte pour intercepter et collecter une partie de la lumiere diffusee par les particules traversant le faisceau d'illumination ; (v) un moyen de traitement de donnees adapte pour capturer et traiter les signaux en provenance du detecteur optique ; l'appareil comportant par ailleurs un moyen permettant d'appliquer un champ magn...
A reliable understanding of the microphysical properties of ice particles in atmospheric clouds i... more A reliable understanding of the microphysical properties of ice particles in atmospheric clouds is critical for assessing cloud radiative forcing effects in climate studies. Ice particle microphysical properties such as size, shape, and surface roughness all have substantial effects on the single-scattering characteristics of the particles. A recently developed ice particle probe, the Small Ice Detector-3 (SID-3), measures the two-dimensional near-forward light-scattering patterns of sampled ice particles. These scattering patterns provide a wealth of information for understanding the microphysical and radiative characteristics of ice particles. The SID-3 was operated successfully on 12 aircraft flights during the NASA Midlatitude Airborne Cirrus Properties Experiment (MACPEX) field campaign in April 2011. In this study, SID-3 measurements are used to investigate the frequency of occurrence of a number of ice particle properties observed during MACPEX. Individual scattering patterns...
Homogeneous freezing of supercooled droplets occurs in convective systems in low and midlatitudes... more Homogeneous freezing of supercooled droplets occurs in convective systems in low and midlatitudes. This droplet-freezing process leads to the formation of a large amount of small ice particles, so-called frozen droplets, that are transported to the upper parts of anvil outflows, where they can influence the cloud radiative properties. However, the detailed microphysics and, thus, the scattering properties of these small ice particles are highly uncertain. Here, the link between the microphysical and optical properties of frozen droplets is investigated in cloud chamber experiments, where the frozen droplets were formed, grown, and sublimated under controlled conditions. It was found that frozen droplets developed a high degree of small-scale complexity after their initial formation and subsequent growth. During sublimation, the small-scale complexity disappeared, releasing a smooth and near-spherical ice particle. Angular light scattering and depolarization measurements confirmed th...
Zbigniew Ulanowski, Paul Kaye, Edwin Hirst, Andreas Wieser, Warren Stanley, ‘Cloud characterizati... more Zbigniew Ulanowski, Paul Kaye, Edwin Hirst, Andreas Wieser, Warren Stanley, ‘Cloud characterization using a particle-counter dropsonde’, poster presented at the European Geosciences Union General Assembly, Vienna, Austria, 12-17 April, 2015.
We describe an optical scattering instrument designed to assess the shapes and sizes of microscop... more We describe an optical scattering instrument designed to assess the shapes and sizes of microscopic atmospheric cloud particles, especially the smallest ice crystals that can profoundly affect cloud processes and radiative properties yet cannot be seen clearly using in situ cloud particle imaging probes. The new instrument captures high-resolution spatial light scattering patterns from individual particles down to ~1 μm in size passing through a laser beam. Its significance lies in the ability of these patterns to provide morphological data for particle sizes well below the optical resolution limits of current probes.
Polarimetric observations of atmospheric Saharan dust over the Canary Islands have provided stron... more Polarimetric observations of atmospheric Saharan dust over the Canary Islands have provided strong evidence for the presence of vertically aligned particles. The alignment was thought to be due to the electric field present because of dust charging. It was concluded that the charging and consequent partial alignment could be a common feature of atmospheric mineral dust layers, influencing the optical
L'invention concerne un ensemble detecteur de fibres (210, 310, 410, 510) comportant : (i) un... more L'invention concerne un ensemble detecteur de fibres (210, 310, 410, 510) comportant : (i) un corps de chambre a diffusion ; (ii) un moyen permettant d'attirer des particules au travers dudit corps de chambre sous la forme d'un flux de particules, ledit moyen etant adapte de sorte que les particules ont tendance a avancer en une seule file, l'axe longitudinal des particules de forme allongee etant sensiblement aligne sur la direction du flux ; (iii) un moyen permettant d'illuminer le flux de particules (212, 312, 412, 413, 512, 513) a l'interieur du corps de chambre ; (iv) un detecteur optique (236, 336, 338, 436, 536, 538) adapte pour intercepter et collecter une partie de la lumiere diffusee par les particules traversant le faisceau d'illumination ; (v) un moyen de traitement de donnees adapte pour capturer et traiter les signaux en provenance du detecteur optique ; l'appareil comportant par ailleurs un moyen permettant d'appliquer un champ magn...
A reliable understanding of the microphysical properties of ice particles in atmospheric clouds i... more A reliable understanding of the microphysical properties of ice particles in atmospheric clouds is critical for assessing cloud radiative forcing effects in climate studies. Ice particle microphysical properties such as size, shape, and surface roughness all have substantial effects on the single-scattering characteristics of the particles. A recently developed ice particle probe, the Small Ice Detector-3 (SID-3), measures the two-dimensional near-forward light-scattering patterns of sampled ice particles. These scattering patterns provide a wealth of information for understanding the microphysical and radiative characteristics of ice particles. The SID-3 was operated successfully on 12 aircraft flights during the NASA Midlatitude Airborne Cirrus Properties Experiment (MACPEX) field campaign in April 2011. In this study, SID-3 measurements are used to investigate the frequency of occurrence of a number of ice particle properties observed during MACPEX. Individual scattering patterns...
Homogeneous freezing of supercooled droplets occurs in convective systems in low and midlatitudes... more Homogeneous freezing of supercooled droplets occurs in convective systems in low and midlatitudes. This droplet-freezing process leads to the formation of a large amount of small ice particles, so-called frozen droplets, that are transported to the upper parts of anvil outflows, where they can influence the cloud radiative properties. However, the detailed microphysics and, thus, the scattering properties of these small ice particles are highly uncertain. Here, the link between the microphysical and optical properties of frozen droplets is investigated in cloud chamber experiments, where the frozen droplets were formed, grown, and sublimated under controlled conditions. It was found that frozen droplets developed a high degree of small-scale complexity after their initial formation and subsequent growth. During sublimation, the small-scale complexity disappeared, releasing a smooth and near-spherical ice particle. Angular light scattering and depolarization measurements confirmed th...
Zbigniew Ulanowski, Paul Kaye, Edwin Hirst, Andreas Wieser, Warren Stanley, ‘Cloud characterizati... more Zbigniew Ulanowski, Paul Kaye, Edwin Hirst, Andreas Wieser, Warren Stanley, ‘Cloud characterization using a particle-counter dropsonde’, poster presented at the European Geosciences Union General Assembly, Vienna, Austria, 12-17 April, 2015.
We describe an optical scattering instrument designed to assess the shapes and sizes of microscop... more We describe an optical scattering instrument designed to assess the shapes and sizes of microscopic atmospheric cloud particles, especially the smallest ice crystals that can profoundly affect cloud processes and radiative properties yet cannot be seen clearly using in situ cloud particle imaging probes. The new instrument captures high-resolution spatial light scattering patterns from individual particles down to ~1 μm in size passing through a laser beam. Its significance lies in the ability of these patterns to provide morphological data for particle sizes well below the optical resolution limits of current probes.
Polarimetric observations of atmospheric Saharan dust over the Canary Islands have provided stron... more Polarimetric observations of atmospheric Saharan dust over the Canary Islands have provided strong evidence for the presence of vertically aligned particles. The alignment was thought to be due to the electric field present because of dust charging. It was concluded that the charging and consequent partial alignment could be a common feature of atmospheric mineral dust layers, influencing the optical
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