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- ItemIntercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment(Katlenburg-Lindau : Copernicus, 2017) Nichman, Leonid; Järvinen, Emma; Dorsey, James; Connolly, Paul; Duplissy, Jonathan; Fuchs, Claudia; Ignatius, Karoliina; Sengupta, Kamalika; Stratmann, Frank; Möhler, Ottmar; Schnaiter, Martin; Gallagher, MartinOptical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at European Organisation for Nuclear Research (CERN). The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of -30, -40 and -50°C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition) were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL) measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI). Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE) and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot separate perfectly spherical ice particles from supercooled droplets. Correlation analysis of bulk averaged path depolarisation measurements and single particle measurements of these clouds showed higher R2 values at high concentrations and small diameters, but these results require further confirmation. We find that none of these instruments were able to determine unambiguously the phase of the small particles. These results have implications for the interpretation of atmospheric measurements and parametrisations for modelling, particularly for low particle number concentration clouds.
- ItemEUREC4A(Katlenburg-Lindau : Copernics Publications, 2021) Stevens, Bjorn; Bony, Sandrine; Farrell, David; Ament, Felix; Blyth, Alan; Fairall, Christopher; Karstensen, Johannes; Quinn, Patricia K.; Speich, Sabrina; Acquistapace, Claudia; Aemisegger, Franziska; Crewell, Susanne; Cronin, Timothy; Cui, Zhiqiang; Cuypers, Yannis; Daley, Alton; Damerell, Gillian M.; Dauhut, Thibaut; Deneke, Hartwig; Desbios, Jean-Philippe; Dörner, Steffen; Albright, Anna Lea; Donner, Sebastian; Douet, Vincent; Drushka, Kyla; Dütsch, Marina; Ehrlich, André; Emanuel, Kerry; Emmanouilidis, Alexandros; Etienne, Jean-Claude; Etienne-Leblanc, Sheryl; Faure, Ghislain; Bellenger, Hugo; Feingold, Graham; Ferrero, Luca; Fix, Andreas; Flamant, Cyrille; Flatau, Piotr Jacek; Foltz, Gregory R.; Forster, Linda; Furtuna, Iulian; Gadian, Alan; Galewsky, Joseph; Bodenschatz, Eberhard; Gallagher, Martin; Gallimore, Peter; Gaston, Cassandra; Gentemann, Chelle; Geyskens, Nicolas; Giez, Andreas; Gollop, John; Gouirand, Isabelle; Gourbeyre, Christophe; de Graaf, Dörte; Caesar, Kathy-Ann; de Groot, Geiske E.; Grosz, Robert; Güttler, Johannes; Gutleben, Manuel; Hall, Kashawn; Harris, George; Helfer, Kevin C.; Henze, Dean; Herbert, Calvert; Holanda, Bruna; Chewitt-Lucas, Rebecca; Ibanez-Landeta, Antonio; Intrieri, Janet; Iyer, Suneil; Julien, Fabrice; Kalesse, Heike; Kazil, Jan; Kellman, Alexander; Kidane, Abiel T.; Kirchner, Ulrike; Klingebiel, Marcus; de Boer, Gijs; Körner, Mareike; Kremper, Leslie Ann; Kretzschmar, Jan; Krüger, Ovid; Kumala, Wojciech; Kurz, Armin; L'Hégaret, Pierre; Labaste, Matthieu; Lachlan-Cope, Tom; Laing, Arlene; Delanoë, Julien; Landschützer, Peter; Lang, Theresa; Lange, Diego; Lange, Ingo; Laplace, Clément; Lavik, Gauke; Laxenaire, Rémi; Le Bihan, Caroline; Leandro, Mason; Lefevre, Nathalie; Denby, Leif; Lena, Marius; Lenschow, Donald; Li, Qiang; Lloyd, Gary; Los, Sebastian; Losi, Niccolò; Lovell, Oscar; Luneau, Christopher; Makuch, Przemyslaw; Malinowski, Szymon; Ewald, Florian; Manta, Gaston; Marinou, Eleni; Marsden, Nicholas; Masson, Sebastien; Maury, Nicolas; Mayer, Bernhard; Mayers-Als, Margarette; Mazel, Christophe; McGeary, Wayne; McWilliams, James C.; Fildier, Benjamin; Mech, Mario; Mehlmann, Melina; Meroni, Agostino Niyonkuru; Mieslinger, Theresa; Minikin, Andreas; Minnett, Peter; Möller, Gregor; Morfa Avalos, Yanmichel; Muller, Caroline; Musat, Ionela; Forde, Marvin; Napoli, Anna; Neuberger, Almuth; Noisel, Christophe; Noone, David; Nordsiek, Freja; Nowak, Jakub L.; Oswald, Lothar; Parker, Douglas J.; Peck, Carolyn; Person, Renaud; George, Geet; Philippi, Miriam; Plueddemann, Albert; Pöhlker, Christopher; Pörtge, Veronika; Pöschl, Ulrich; Pologne, Lawrence; Posyniak, Michał; Prange, Marc; Quiñones Meléndez, Estefanía; Radtke, Jule; Gross, Silke; Ramage, Karim; Reimann, Jens; Renault, Lionel; Reus, Klaus; Reyes, Ashford; Ribbe, Joachim; Ringel, Maximilian; Ritschel, Markus; Rocha, Cesar B.; Rochetin, Nicolas; Hagen, Martin; Röttenbacher, Johannes; Rollo, Callum; Royer, Haley; Sadoulet, Pauline; Saffin, Leo; Sandiford, Sanola; Sandu, Irina; Schäfer, Michael; Schemann, Vera; Schirmacher, Imke; Hausold, Andrea; Schlenczek, Oliver; Schmidt, Jerome; Schröder, Marcel; Schwarzenboeck, Alfons; Sealy, Andrea; Senff, Christoph J.; Serikov, Ilya; Shohan, Samkeyat; Siddle, Elizabeth; Smirnov, Alexander; Heywood, Karen J.; Späth, Florian; Spooner, Branden; Stolla, M. Katharina; Szkółka, Wojciech; de Szoeke, Simon P.; Tarot, Stéphane; Tetoni, Eleni; Thompson, Elizabeth; Thomson, Jim; Tomassini, Lorenzo; Hirsch, Lutz; Totems, Julien; Ubele, Alma Anna; Villiger, Leonie; von Arx, Jan; Wagner, Thomas; Walther, Andi; Webber, Ben; Wendisch, Manfred; Whitehall, Shanice; Wiltshire, Anton; Jacob, Marek; Wing, Allison A.; Wirth, Martin; Wiskandt, Jonathan; Wolf, Kevin; Worbes, Ludwig; Wright, Ethan; Wulfmeyer, Volker; Young, Shanea; Zhang, Chidong; Zhang, Dongxiao; Jansen, Friedhelm; Ziemen, Florian; Zinner, Tobias; Zöger, Martin; Kinne, Stefan; Klocke, Daniel; Kölling, Tobias; Konow, Heike; Lothon, Marie; Mohr, Wiebke; Naumann, Ann Kristin; Nuijens, Louise; Olivier, Léa; Pincus, Robert; Pöhlker, Mira; Reverdin, Gilles; Roberts, Gregory; Schnitt, Sabrina; Schulz, Hauke; Siebesma, A. Pier; Stephan, Claudia Christine; Sullivan, Peter; Touzé-Peiffer, Ludovic; Vial, Jessica; Vogel, Raphaela; Zuidema, Paquita; Alexander, Nicola; Alves, Lyndon; Arixi, Sophian; Asmath, Hamish; Bagheri, Gholamhossein; Baier, Katharina; Bailey, Adriana; Baranowski, Dariusz; Baron, Alexandre; Barrau, Sébastien; Barrett, Paul A.; Batier, Frédéric; Behrendt, Andreas; Bendinger, Arne; Beucher, Florent; Bigorre, Sebastien; Blades, Edmund; Blossey, Peter; Bock, Olivier; Böing, Steven; Bosser, Pierre; Bourras, Denis; Bouruet-Aubertot, Pascale; Bower, Keith; Branellec, Pierre; Branger, Hubert; Brennek, Michal; Brewer, Alan; Brilouet, Pierre-Etienne; Brügmann, Björn; Buehler, Stefan A.; Burke, Elmo; Burton, Ralph; Calmer, Radiance; Canonici, Jean-Christophe; Carton, Xavier; Cato Jr., Gregory; Charles, Jude Andre; Chazette, Patrick; Chen, Yanxu; Chilinski, Michal T.; Choularton, Thomas; Chuang, Patrick; Clarke, Shamal; Coe, Hugh; Cornet, Céline; Coutris, Pierre; Couvreux, FleurThe science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.
- ItemObservation of viscosity transition in α-pinene secondary organic aerosol(München : European Geopyhsical Union, 2016) Järvinen, Emma; Ignatius, Karoliina; Nichman, Leonid; Kristensen, Thomas B.; Fuchs, Claudia; Hoyle, Christopher R.; Höppel, Niko; Corbin, Joel C.; Craven, Jill; Duplissy, Jonathan; Ehrhart, Sebastian; El Haddad, Imad; Frege, Carla; Gordon, Hamish; Jokinen, Tuija; Kallinger, Peter; Kirkby, Jasper; Kiselev, Alexei; Naumann, Karl-Heinz; Petäjä, Tuukka; Pinterich, Tamara; Prevot, Andre S.H.; Saathoff, Harald; Schiebel, Thea; Sengupta, Kamalika; Simon, Mario; Slowik, Jay G.; Tröstl, Jasmin; Virtanen, Annele; Vochezer, Paul; Vogt, Steffen; Wagner, Andrea C.; Wagner, Robert; Williamson, Christina; Winkler, Paul M.; Yan, Chao; Baltensperger, Urs; Donahue, Neil M.; Flagan, Rick C.; Gallagher, Martin; Hansel, Armin; Kulmala, Markku; Stratmann, Frank; Worsnop, Douglas R.; Möhler, Ottmar; Leisner, Thomas; Schnaiter, MartinUnder certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of α-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity-transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
- ItemGlobal-scale atmosphere monitoring by in-service aircraft – current achievements and future prospects of the European Research Infrastructure IAGOS(Milton Park : Taylor & Francis, 2015) Petzold, Andreas; Thouret, Valerie; Gerbig, Christoph; Zahn, Andreas; Brenninkmeijer, Carl A.M.; Gallagher, Martin; Hermann, Markus; Pontaud, Marc; Ziereis, Helmut; Boulanger, Damien; Marshall, Julia; Nédélec, Philippe; Smit, Herman G.J.; Friess, Udo; Flaud, Jean-Marie; Wahner, Andreas; Cammas, Jean-Pierre; Volz-Thomas, AndreasThe European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System) operates a global-scale monitoring system for atmospheric trace gases, aerosols and clouds utilising the existing global civil aircraft. This new monitoring infrastructure builds on the heritage of the former research projects MOZAIC (Measurement of Ozone and Water Vapour on Airbus In-service Aircraft) and CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container). CARIBIC continues within IAGOS and acts as an important airborne measurement reference standard within the wider IAGOS fleet. IAGOS is a major contributor to the in-situ component of the Copernicus Atmosphere Monitoring Service (CAMS), the successor to the Global Monitoring for the Environment and Security – Atmospheric Service, and is providing data for users in science, weather services and atmospherically relevant policy. IAGOS is unique in collecting regular in-situ observations of reactive gases, greenhouse gases and aerosol concentrations in the upper troposphere and lowermost stratosphere (UTLS) at high spatial resolution. It also provides routine vertical profiles of these species in the troposphere over continental sites or regions, many of which are undersampled by other networks or sampling studies, particularly in Africa, Southeast Asia and South America. In combination with MOZAIC and CARIBIC, IAGOS has provided long-term observations of atmospheric chemical composition in the UTLS since 1994. The longest time series are 20 yr of temperature, H2O and O3, and 9–15 yr of aerosols, CO, NO y , CO2, CH4, N2O, SF6, Hg, acetone, ~30 HFCs and ~20 non-methane hydrocarbons. Among the scientific highlights which have emerged from these data sets are observations of extreme concentrations of O3 and CO over the Pacific basin that have never or rarely been recorded over the Atlantic region for the past 12 yr; detailed information on the temporal and regional distributions of O3, CO, H2O, NO y and aerosol particles in the UTLS, including the impacts of cross-tropopause transport, deep convection and lightning on the distribution of these species; characterisation of ice-supersaturated regions in the UTLS; and finally, improved understanding of the spatial distribution of upper tropospheric humidity including the finding that the UTLS is much more humid than previously assumed.