Tropospheric and stratospheric smoke over Europe as observed within EARLINET/ACTRIS in summer 2017
Creators: name: Baars, Holger
name: Acheson, Karen
name: Althausen, Dietrich
name: Amiridis, Vassilis
name: Amodeo, Aldo
name: Ansmann, Albert
name: Apituley, Arnoud
name: Alados Arboledas, Lucal
name: Baldasano, José M.
name: Baray, Jean-Luc
name: Barragán, Rubén
name: Belegante, Livio
name: Antonio Benavent-Oltra, Jose
name: Bortoli, Daniele
name: Bühl, Johannes
name: Comeron, Adolfo
name: Córdoba, Carmen
name: D'Amico, Guiseppe
name: Del Aguila, Ana
name: Dionisi, Davide
name: Ene, Dragos
name: Engelmann, Ronny
name: Fernández García, Alfonso Javier
name: Fréville, Patrick
name: Gausa, Michael
name: Gialitaki, Anna
name: Goloub, Philippe
name: Grigorov, Ivan
name: Guerrero-Rascado, Jean Luis
name: Haarig, Moritz
name: Haefele, Alexander
name: Haeffelin, Martial
name: Hanuš, Vlastimil
name: Heese, Birgit
name: Hervo, Maxime
name: Hofer, Julian
name: Hu, Qiaoyun
name: Iarlori, Marco
name: Jimenez, Cristofer
name: Liberti, Gianluigi
name: Marinou, Eleni
name: Martucci, Giovanni
name: Mattis, Ina
name: Mona, Lucia
name: Montoux, Nadège
name: Müller, Detlef
name: Mylonaki, Maria
name: Nicolae, Doina
name: Ortiz-Amezcua, Pablo
name: Papagiannopoulos, Nikos
name: Papayannis, Alex
name: Perrone, Maria Rita
name: Pietras, Christophe
name: Pietruczuk, Aleksander
name: Podvin, Thierry
name: Popovici, Ioana
name: Proestakis, Emmanouil
name: Radenz, Martin
name: Romano, Salvatore
name: Schechner, Yoav
name: Seifert, Patric
name: Sicard, Michael
name: Skupin, Annett
name: Soupiona, Ourania
name: Stachlewska, Iwona S.
name: Tetoni, Eleni
name: Trickl, Thomas
name: Vesselovski, Igor
name: Vladimir, Zdimal
name: Vogelmann, Hannes
name: Wandinger, Ulla
Publisher: name: Karlsruhe
Year: 2018
Subjects: EARLINET
ACTRIS
stratospheric smoke
lidar

description: For several weeks in summer 2017, strong smoke layers were observed over Europe at numerous EARLINET stations. EARLINET is the European research lidar network and part of ACTRIS and comprises more than 30 ground-based lidars. The smoke layers were observed in the troposphere as well as in the stratosphere up to 25 km from Northern Scandinavia over whole western and central Europe to the Mediterranean regions. Backward trajectory analysis among other tools revealed that these smoke layers originated from strong wild fires in western Canada in combination with pyrocumulus convection. An extraordinary fire event in the mid of August caused intense smoke layers that were observed across Europe for several weeks starting on 18 August 2017. Maximum aerosol optical depths up to 1.0 at 532 nm were observed at Leipzig, Germany, on 22 August 2017 during the peak of this event. The stratospheric smoke layers reached extinction coefficient values of more than 600 Mm−1 at 532 nm, a factor of 10 higher than observed for volcanic ash after the Pinatubo eruption in the 1990s. First analyses of the intensive optical properties revealed low particle depolarization values at 532 nm for the tropospheric smoke (spherical particles) and rather high values (up to 20%) in the stratosphere. However, a strong wavelength dependence of the depolarization ratio was measured for the stratospheric smoke. This indicates irregularly shaped stratospheric smoke particles in the size range of the accumulation mode. This unique depolarization feature makes it possible to distinguish clearly smoke aerosol from cirrus clouds or other aerosol types by polarization lidar measurements. Particle extinction-to-backscatter ratios were rather low in the order of 40 to 50 sr at 355 nm, while values between 70-90 sr were measured at higher wavelengths. In the western and central Mediterranean, stratospheric smoke layers were most prominent in the end of August at heights between 16 and 20 km. In contrast, stratospheric smoke started to occur in the eastern Mediterranean (Cyprus and Israel) in the beginning of September between 18 and 23 km. Stratospheric smoke was still visible in the beginning of October at certain locations (e.g. Evora, Portugal), while tropospheric smoke was mainly observed until the end of August within Europe. An overview of the smoke layers measured at several EARLINET sites will be given. The temporal development of these layers as well as their geometrical and optical properties will be presented.