8 January 2015 Two-wavelength lidar characterization of optical, dynamical, and microphysical properties of Saharan dust layers over Sofia, Bulgaria
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Proceedings Volume 9447, 18th International School on Quantum Electronics: Laser Physics and Applications; 94470R (2015) https://doi.org/10.1117/12.2175654
Event: Eighteenth International School on Quantum Electronics: Laser Physics and Applications, 2014, Sozopol, Bulgaria
Abstract
In this work, we present results of two-wavelength lidar observations on Saharan dust layers over Sofia, Bulgaria, in two days of strong dust intrusion events in the fall and winter of the year 2010. Measurements are carried out at two wavelengths (1064 nm and 532 nm) by using two channels of an aerosol lidar based on a frequency-doubled Nd:YAG laser. Optical, dynamical, and microphysical properties of the dust layers are studied and analyzed, distinguishing specifics of coarse and fine aerosol fractions. The spatial-temporal evolution of atmospheric aerosol/dust density fluctuations is shown on height-time coordinate color-map plots for each of the two wavelengths. Time-averaged height profiles of the atmospheric backscattering coefficient at 1064 nm and 532 nm are presented, showing the dust and aerosol density distribution up to about 10 km AGL, with a range/height resolution of 15/8 m. Microphysical properties of dust and aerosol particles are characterized qualitatively by using backscatter-related Ǻngström exponents (BAE). Range-resolved time-averaged height profiles of BAE are shown, particularly for the dust layers, indicating the dominating particle size-modes. Obtained BAE values in the range 0.2-0.5 are typical for desert mineral dust, suggesting coarse particles in the over-micron size range. Frequency-count analysis of the obtained BAE arrays is performed for typical separate dust-containing layers, revealing distributions and changes of particle size modes in terms of BAE, as well as effects of dust mixing with finer urban and industrial aerosols. Some efforts are devoted and focused on characterizing the temporal dynamics of the range distribution and density of dust and aerosols. Peculiarities of spatial distribution, size composition, and temporal evolution of Saharan dust aerosols are revealed, analyzed, and discussed.
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Zahary Y. Peshev, Tsvetina T. Evgenieva, Tanja N. Dreischuh, Dimitar V. Stoyanov, "Two-wavelength lidar characterization of optical, dynamical, and microphysical properties of Saharan dust layers over Sofia, Bulgaria ", Proc. SPIE 9447, 18th International School on Quantum Electronics: Laser Physics and Applications, 94470R (8 January 2015); doi: 10.1117/12.2175654; https://doi.org/10.1117/12.2175654
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