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Profiling of Saharan dust and biomass-burning smoke with multiwavelength polarization Raman lidar at Cape Verde

Tesche, Matthias and Gross, Silke and Ansmann, Albert and Müller, Detlef and Althausen, Dietrich and Freudenthaler, Volker and Esselborn, Michael (2011) Profiling of Saharan dust and biomass-burning smoke with multiwavelength polarization Raman lidar at Cape Verde. Tellus B - Chemical and Physical Meteorology, 63 (4), pp. 649-676. Taylor & Francis. DOI: 10.1111/j.1600-0889.2011.00548.x ISSN 0280-6509

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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 532nm, respectively, prevailed. Within these layers, wavelength-independent linear particle depolarization ratios of 0.12-0.18 at 355, 532, and 710nm 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-1 at 355nm and 48 ± 5 Mm-1 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-1 at 355 and 532nm. 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 532nm to 0.37 ± 0.07 at 710 nm.

Item URL in elib:https://elib.dlr.de/97008/
Document Type:Article
Title:Profiling of Saharan dust and biomass-burning smoke with multiwavelength polarization Raman lidar at Cape Verde
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Tesche, MatthiasIfT, LeipzigUNSPECIFIED
Ansmann, AlbertIfT, LeipzigUNSPECIFIED
Müller, DetlefIfT, LeipzigUNSPECIFIED
Althausen, DietrichIfT, LeipzigUNSPECIFIED
Freudenthaler, VolkerUniversität MünchenUNSPECIFIED
Journal or Publication Title:Tellus B - Chemical and Physical Meteorology
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:No
DOI :10.1111/j.1600-0889.2011.00548.x
Page Range:pp. 649-676
Publisher:Taylor & Francis
Keywords:lidar measurements , Saharan dust , Sun photometer, Dust depolarization
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben LIDAR-Forschung und -Entwicklung
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Lidar
Deposited By: Kiemle, Dr.rer.nat. Christoph
Deposited On:09 Jul 2015 12:17
Last Modified:08 Mar 2018 18:52

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