4 results
Search Results
Now showing 1 - 4 of 4
- ItemFour-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET(München : European Geopyhsical Union, 2013) Pappalardo, G.; Mona, L.; D'Amico, G.; Wandinger, U.; Adam, M.; Amodeo, A.; Ansmann, A.; Apituley, A.; Alados Arboledas, L.; Balis, D.; Boselli, A.; Bravo-Aranda, J.A.; Chaikovsky, A.; Comeron, A.; Cuesta, J.; De Tomasi, F.; Freudenthaler, V.; Gausa, M.; Giannakaki, E.; Giehl, H.; Giunta, A.; Grigorov, I.; Groß, S.; Haeffelin, M.; Hiebsch, A.; Iarlori, M.; Lange, D.; Linné, H.; Madonna, F.; Mattis, I.; Mamouri, R.-E.; McAuliffe, M.A.P.; Mitev, V.; Molero, F.; Navas-Guzman, F.; Nicolae, D.; Papayannis, A.; Perrone, M.R.; Pietras, C.; Pietruczuk, A.; Pisani, G.; Preißler, J.; Pujadas, M.; Rizi, V.; Ruth, A.A.; Schmidt, J.; Schnell, F.; Seifert, P.; Serikov, I.; Sicard, M.; Simeonov, V.; Spinelli, N.; Stebel, K.; Tesche, M.; Trickl, T.; Wang, X.; Wagner, F.; Wiegner, M.; Wilson, K.M.The eruption of the Icelandic volcano Eyjafjallajökull in April–May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April–26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at http://www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5–15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.
- ItemSurface matters: Limitations of CALIPSO V3 aerosol typing in coastal regions(München : European Geopyhsical Union, 2014) Kanitz, T.; Ansmann, A.; Foth, A.; Seifert, P.; Wandinger, U.; Engelmann, R.; Baars, H.; Althausen, D.; Casiccia, C.; Zamorano, F.In the CALIPSO data analysis, surface type (land/ocean) is used to augment the aerosol characterization. However, this surface-dependent aerosol typing prohibits a correct classification of marine aerosol over land that is advected from ocean to land. This might result in a systematic overestimation of the particle extinction coefficient and of the aerosol optical thickness (AOT) of up to a factor of 3.5 over land in coastal areas. We present a long-term comparison of CALIPSO and ground-based lidar observations of the aerosol conditions in the coastal environment of southern South America (Punta Arenas, Chile, 53° S), performed in December 2009–April 2010. Punta Arenas is almost entirely influenced by marine particles throughout the year, indicated by a rather low AOT of 0.02–0.04. However, we found an unexpectedly high fraction of continental aerosol in the aerosol types inferred by means of CALIOP observations and, correspondingly, too high values of particle extinction. Similar features of the CALIOP data analysis are presented for four other coastal areas around the world. Since CALIOP data serve as important input for global climate models, the influence of this systematic error was estimated by means of simplified radiative-transfer calculations.
- ItemObservations of turbulence-induced new particle formation in the residual layer(München : European Geopyhsical Union, 2010) Wehner, B.; Siebert, H.; Ansmann, A.; Ditas, F.; Seifert, P.; Stratmann, F.; Wiedensohler, A.; Apituley, A.; Shaw, R.A.; Manninen, H.E.; Kulmala, M.Aerosol particle measurements in the atmospheric boundary layer performed by a helicopter-borne measurement payload and by a lidar system from a case study during the IMPACT field campaign in Cabauw (NL) are presented. Layers of increased number concentrations of ultrafine particles were observed in the residual layer, indicating relatively recent new-particle formation. These layers were characterized by a sub-critical Richardson number and concomitant increased turbulence. Turbulent mixing is likely to lead to local supersaturation of possible precursor gases which are essential for new particle formation. Observed peaks in the number concentrations of ultrafine particles at ground level are connected to the new particle formation in the residual layer by boundary layer development and vertical mixing.
- ItemAerosol measurements with a shipborne Sun-sky-lunar photometer and collocated multiwavelength Raman polarization lidar over the Atlantic Ocean(Göttingen : Copernicus GmbH, 2019) Yin, Z.; Ansmann, A.; Baars, H.; Seifert, P.; Engelmann, R.; Radenz, M.; Jimenez, C.; Herzog, A.; Ohneiser, K.; Hanbuch, K.; Blarel, L.; Goloub, P.; Victori, S.; Maupin, F.A shipborne Sun-sky-lunar photometer of type CE318-T was tested during two trans-Atlantic cruises aboard the German research vessel Polarstern from 54ĝ N to 54ĝ S in May/June and December 2018. The continuous observations of the motion-stabilized shipborne CE318-T enabled the first-time observation of a full diurnal cycle of aerosol optical depth (AOD) and column-mean Ångström coefficient of a mixed dust-smoke episode. The latitudinal distribution of the AOD from the shipborne CE318-T, Raman lidar and MICROTOPS II shows the same trend with highest values in the dust belt from 0 to 20ĝ N and overall low values in the Southern Hemisphere. The linear-regression coefficients of determination between MICROTOPS II and the CE318-T were 0.988, 0.987, 0.994 and 0.994 for AODs at 380, 440, 500 and 870 nm and 0.896 for the Ångström exponent at 440-870 nm. The root-mean-squared differences of AOD at 380, 440, 500 and 870 nm were 0.015, 0.013, 0.010 and 0.009, respectively.