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Original Research Papers

Numerical simulations of optical properties of Saharan dust aerosols with emphasis on lidar applications

Authors:

M. Wiegner ,

Ludwig-Maximilians-Universität, Meteorologisches Institut, DE
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J. Gasteiger,

Ludwig-Maximilians-Universität, Meteorologisches Institut, DE
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K. Kandler,

Institute for Applied Geosciences, Darmstadt University of Technology, DE
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B. Weinzierl,

Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, DE
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K. Rasp,

Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, DE
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M. Esselborn,

Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, DE
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V. Freudenthaler,

Ludwig-Maximilians-Universität, Meteorologisches Institut, DE
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B. Heese,

Ludwig-Maximilians-Universität, Meteorologisches Institut; Institute for Tropospheric Research (IfT), DE
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C. Toledano,

Ludwig-Maximilians-Universität, Meteorologisches Institut, DE
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M. Tesche,

Institute for Tropospheric Research (IfT), DE
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D. Althausen

Institute for Tropospheric Research (IfT), DE
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Abstract

In the framework of the Saharan Mineral Dust Experiment (SAMUM) for the first time the spectral dependence of particle linear depolarization ratios was measured by combining four lidar systems. In this paper these measurements are compared with results from scattering theory based on the T-matrix method. For this purpose, in situ measurements—size distribution, shape distribution and refractive index—were used as input parameters; particle shape was approximated by spheroids. A sensitivity study showed that lidar-related parameters—lidar ratio Sp and linear depolarization ratio δp—are very sensitive to changes of all parameters. The simulated values of the δp are in the range of 20% and 31% and thus in the range of the measurements. The spectral dependence is weak, so that it could not be resolved by the measurements. Calculated lidar ratios based on the measured microphysics and considering equivalent radii up to 7.5μm show a range of possible values between 29 and 50 sr at λ = 532 nm. Larger Sp might be possible if the real part of the refractive index is small and the imaginary part is large. A strict validation was however not possible as too many microphysical parameters influence Sp and δp that could not be measured with the required accuracy.

How to Cite: Wiegner, M., Gasteiger, J., Kandler, K., Weinzierl, B., Rasp, K., Esselborn, M., Freudenthaler, V., Heese, B., Toledano, C., Tesche, M. and Althausen, D., 2009. Numerical simulations of optical properties of Saharan dust aerosols with emphasis on lidar applications. Tellus B: Chemical and Physical Meteorology, 61(1), pp.180–194. DOI: http://doi.org/10.1111/j.1600-0889.2008.00381.x
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  Published on 01 Jan 2009
 Accepted on 1 Aug 2008            Submitted on 19 Dec 2007

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