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TESCHE, MATTHIAS,GROSS, SILKE,ANSMANN, ALBERT,MÜ,LLER, DETLEF,ALTHAUSEN, DIETRICH,FREUDENTHALER, VOLKER,ESSELBORN, MICHAEL Blackwell Publishing Ltd 2011 Tellus. Series B, Chemical and physical meteorolog Vol.63 No.4
<P><B>ABSTRACT</B></P><P>Extensive lidar measurements of Saharan dust and biomass‐burning smoke were performed with one airborne and three ground‐based instruments in the framework of the second part of the SAharan Mineral dUst experiMent (SAMUM‐2a) during January and February of 2008 at Cape Verde. Further lidar observations with one system only were conducted during May and June of 2008 (SAMUM‐2b). The active measurements were supported by Sun photometer observations. During winter, layers of mineral dust from the Sahara and biomass‐burning smoke from southern West Africa pass Cape Verde on their way to South America while pure dust layers cross the Atlantic on their way to the Caribbean during summer. The mean 500‐nm aerosol optical thickness (AOT) observed during SAMUM‐2a was 0.35 ± 0.18. SAMUM‐2a observations showed transport of pure dust within the lowermost 1.5 km of the atmospheric column. In the height range from 1.5 to 5.0 km, mixed dust/smoke layers with mean lidar ratios of 67 ± 14 sr at 355 and 532 nm, respectively, prevailed. Within these layers, wavelength‐independent linear particle depolarization ratios of 0.12–0.18 at 355, 532, and 710 nm indicate a large contribution (30–70%) of mineral dust to the measured optical properties. Ångström exponents for backscatter and extinction of around 0.7 support this finding. Mean extinction coefficients in the height range between 2 and 4 km were 66 ± 6 Mm<SUP>−1</SUP> at 355 nm and 48 ± 5 Mm<SUP>−1</SUP> at 532 nm. Comparisons with airborne high‐spectral‐resolution lidar observations show good agreement within the elevated layers. 3–5 km deep dust layers where observed during SAMUM‐2b. These layers showed optical properties similar to the ones of SAMUM‐1 in Morocco with a mean 500‐nm AOT of 0.4 ± 0.2. Dust extinction coefficients were about 80 ± 6 Mm<SUP>−1</SUP> at 355 and 532 nm. Dust lidar ratios were 53 ± 10 sr at 355 and 532 nm, respectively. Dust depolarization ratios showed an increase with wavelength from 0.31 ± 0.10 at 532 nm to 0.37 ± 0.07 at 710 nm.</P>
TESCHE, MATTHIAS,MÜ,LLER, DETLEF,GROSS, SILKE,ANSMANN, ALBERT,ALTHAUSEN, DIETRICH,FREUDENTHALER, VOLKER,WEINZIERL, BERNADETT,VEIRA, ANDREAS,PETZOLD, ANDREAS Blackwell Publishing Ltd 2011 Tellus. Series B, Chemical and physical meteorolog Vol.63 No.4
<P><B>ABSTRACT</B></P><P>Lidar measurements of mixed dust/smoke plumes over the tropical Atlantic ocean were carried out during the winter campaign of SAMUM‐2 at Cape Verde. Profiles of backscatter and extinction coefficients, lidar ratios, and Ångström exponents related to pure biomass‐burning aerosol from southern West Africa were extracted from these observations. Furthermore, these findings were used as input for an inversion algorithm to retrieve microphysical properties of pure smoke. Seven measurement days were found suitable for the procedure of aerosol‐type separation and successive inversion of optical data that describe biomass‐burning smoke. We inferred high smoke lidar ratios of 87 ± 17 sr at 355 nm and 79 ± 17 sr at 532 nm. Smoke lidar ratios and Ångström exponents are higher compared to the ones for the dust/smoke mixture. These numbers indicate higher absorption and smaller sizes for pure smoke particles compared to the dust/smoke mixture. Inversion of the smoke data set results in mean effective radii of 0.22 ± 0.08 μm with individual results varying between 0.10 and 0.36 μm. The single‐scattering albedo for pure biomass‐burning smoke was found to vary between 0.63 and 0.89 with a very low mean value of 0.75 ± 0.07. This is in good agreement with findings of airborne in situ measurements which showed values of 0.77 ± 0.03. Effective radii from the inversion were similar to the ones found for the fine mode of the in situ size distributions.</P>
Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008-2009
Mattis, Ina,Siefert, Patric,Mü,ller, Detlef,Tesche, Matthias,Hiebsch, Anja,Kanitz, Thomas,Schmidt, Jö,rg,Finger, Fanny,Wandinger, Ulla,Ansmann, Albert American Geophysical Union 2010 Journal of Geophysical Research Vol.115 No.d2
<P>In the framework of regular European Aerosol Research Lidar Network (EARLINET) observations, aerosol layers have been monitored with a multiwavelength aerosol Raman lidar in the upper troposphere and lower stratosphere over Leipzig (51.4 degrees N, 12.4 degrees E), Germany, since the summer of 2008. The origins of these layers are eruptions of different volcanoes on the Aleutian Islands, Kamchatka, Alaska, and on the Kuril Islands. FLEXPART transport simulations show that the volcanic aerosol is advected from Alaska to central Europe within about 7 days. The aerosol layers typically occurred in the upper troposphere above 5 km height and in the lower stratosphere below 25 km height. The optical depths of the volcanic aerosol layers are mostly between 0.004 and 0.025 at 532 nm. The wavelength dependence of the backscatter coefficients and extinction coefficients indicate Angstrom exponents from 1.0-2.0. Lidar ratios in the stratosphere are found in the range from 30-60 sr (355 nm) and 30-45 sr (532 nm). The estimation of the effective radius, surface-area, and mass concentrations of a volcanic aerosol layer, observed well within the stratosphere at end of August 2009, reveals values of 0.1-0.2 mu m, 5-10 mu m(2) cm(-3), and 0.3-0.5 mu g m(-3), respectively.</P>