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- ItemIs the near-spherical shape the "new black" for smoke?(Katlenburg-Lindau : EGU, 2020) Gialitaki, Anna; Tsekeri, Alexandra; Amiridis, Vassilis; Ceolato, Romain; Paulien, Lucas; Kampouri, Anna; Gkikas, Antonis; Solomos, Stavros; Marinou, Eleni; Haarig, Moritz; Baars, Holger; Ansmann, Albert; Lapyonok, Tatyana; Lopatin, Anton; Dubovik, Oleg; Groß, Silke; Wirth, Martin; Tsichla, Maria; Tsikoudi, Ioanna; Balis, DimitrisWe examine the capability of near-sphericalshaped particles to reproduce the triple-wavelength particle linear depolarization ratio (PLDR) and lidar ratio (LR) values measured over Europe for stratospheric smoke originating from Canadian wildfires. The smoke layers were detected both in the troposphere and the stratosphere, though in the latter case the particles presented PLDR values of almost 18% at 532 nm as well as a strong spectral dependence from the UV to the near-IR wavelength. Although recent simulation studies of rather complicated smoke particle morphologies have shown that heavily coated smoke aggregates can produce large PLDR, herein we propose a much simpler model of compact near-spherical smoke particles. This assumption allows for the reproduction of the observed intensive optical properties of stratospheric smoke, as well as their spectral dependence. We further examine whether an extension of the current Aerosol Robotic Network (AERONET) scattering model to include the near-spherical shapes could be of benefit to the AERONET retrieval for stratospheric smoke cases associated with enhanced PLDR. Results of our study illustrate the fact that triple-wavelength PLDR and LR lidar measurements can provide us with additional insight when it comes to particle characterization. © 2020 Author(s).
- 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.
- ItemDepolarization ratio profiling at several wavelengths in pure Saharan dust during SAMUM 2006(Milton Park : Taylor & Francis, 2017) Freudenthaler, Volker; Esselborn, Michael; Wiegner, Matthias; Heese, Birgit; Tesche, Matthias; Ansmann, Albert; Müller, Detlef; Althausen, Dietrich; Wirth, Martin; Fix, Andreas; Ehret, Gerhard; Knippertz, Peter; Toledano, Carlos; Gasteiger, Josef; Garhammer, Markus; Seefeldner, MeinhardVertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9◦N, –6.9◦E), close to source regions in May–June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean Ångström exponent (AE, 440–870 nm) of 0.18 (range 0.04–0.34) and still high mean linear particle depolarization ratio between 0.21 and 0.25 during periods with aerosol optical thickness less than 0.1, with a mean AE of 0.76 (range 0.65–1.00), which represents a negative correlation of the linear particle depolarization ratio with the AE. A slight decrease of the linear particle depolarization ratio with wavelength was found between 532 and 1064 nm from 0.31 ± 0.03 to 0.27 ± 0.04.
- ItemMicrophysical and optical properties of dust and tropical biomass burning aerosol layers in the Cape Verde region - an overview of the airborne in situ and lidar measurements during SAMUM-2(Milton Park : Taylor & Francis, 2017) Weinzierl, Bernadett; Sauer, Daniel; Esselborn, Michael; Petzold, Andreas; Veira, Andreas; Rose, Maximilian; Mund, Susanne; Wirth, Martin; Ansmann, Albert; Tesche, Matthias; Gross, Silke; Freudenthaler, VolkerIn the framework of the Saharan Mineral Dust Experiment (SAMUM) airborne High Spectral Resolution Lidar and in situ measurements of the particle size, aerosol mixing state and absorption coefficient were conducted. Here, the properties of mineral dust and tropical biomass burning layers in the Cape Verde region in January/February 2008 are investigated and compared with the properties of fresh dust observed in May/June 2006 close the Sahara. In the Cape Verde area, we found a complex stratification with dust layers covering the altitude range below 2 km and biomass burning layers aloft. The aerosol type of the individual layers was classified based on depolarization and lidar ratios and, in addition, on in situ measured Ångström exponents of absorption åap. The dust layers had a depth of 1.3 ± 0.4 km and showed a median åap of 3.95. The median effective diameter Deff was 2.5 μm and the dust layers over Cape Verde yielded clear signals of aging: large particles were depleted due to gravitational settling and the accumulation mode diameter was shifted towards larger sizes as a result of coagulation. The tropical biomass layers had a depth of 2.0 ± 1.1 km and were characterized by a median åap of 1.34. They always contained a certain amount of large dust particles and showed a median Deff of 1.1 μm and a fine mode Deff,fine of 0.33. The dust and biomass burning layers had a median aerosol optical depth (AOD) of 0.23 and 0.09, respectively. The median contributions to the AOD of the total atmospheric column below 10 km were 75 and 37%, respectively.
- ItemSpatial distribution and optical properties of Saharan dust observed by airborne high spectral resolution lidar during SAMUM 2006(Milton Park : Taylor & Francis, 2017) Esselborn, Michael; Wirth, Martin; Fix, Andreas; Weinzierl, Bernadett; Rasp, Katharina; Tesche, Matthias; Petzold, AndreasAirborne measurements of pure Saharan dust extinction and backscatter coefficients, the corresponding lidar ratio and the aerosol optical thickness (AOT) have been performed during the Saharan Mineral Dust Experiment 2006, with a high spectral resolution lidar. Dust layers were found to range from ground up to 4–6 km above sea level (asl). Maximum AOT values at 532 nm, encountered within these layers during the DLR Falcon research flights were 0.50–0.55. A significant horizontal variability of the AOT south of the High Atlas mountain range was observed even in cases of a well-mixed dust layer. High vertical variations of the dust lidar ratio of 38–50 sr were observed in cases of stratified dust layers. The variability of the lidar ratio was attributed to dust advection from different source regions. The aerosol depolarization ratio was about 30% at 532 nm during all measurements and showed only marginal vertical variations.