Please use this identifier to cite or link to this item:
Files in This Item:
File SizeFormat 
j.1600-0889.2011.00548.pdf3.57 MBAdobe PDFView/Open
Title: Profiling of Saharan dust and biomass-burning smoke with multiwavelength polarization Raman lidar at Cape Verde
Authors: Tesche, MatthiasGross, SilkeAnsmann, AlbertMüller, DetlefAlthausen, DietrichFreudenthaler, VolkerEsselborn, Michael
Publishers Version:
Issue Date: 2017
Published in: Tellus B: Chemical and Physical Meteorology , Volume 63, Issue 4, Page 649-676
Publisher: Milton Park : Taylor & Francis
Abstract: 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 duringMay 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. Ångstr¨om 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 355 nm 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 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.
Keywords: aerosol property; airborne survey; atmospheric transport; biomass burning; dust; extinction coefficient; ground-based measurement; lidar; smoke
DDC: 550
License: CC BY 4.0 Unported
Link to License:
Appears in Collections:Geowissenschaften

This item is licensed under a Creative Commons License Creative Commons