Abstract
West Africa and the adjacent oceanic regions are very important locations for studying dust properties and their influence on weather and climate. The SHADOW (Study of SaHAran Dust Over West Africa) campaign is performing a multi-scale and multi-laboratory study of aerosol properties and dynamics using a set of in situ and remote sensing instruments at an observation site located at IRD (Institute for Research and Development) Center, Mbour, Senegal (14°N, 17°W). In this paper, we present the results of lidar measurements performed during the first phase of SHADOW which occurred in March-April, 2015. The multiwavelength Mie-Raman lidar acquired 3β+2α+1δ measurements during this period. This set of measurements has permitted particle intensive properties such as extinction and backscattering Angstrom exponents (BAE) for 355/532 nm wavelengths corresponding lidar ratios and depolarization ratio at 532 nm to be determined. The backscattering Angstrom exponent during the dust episodes decreased to ~-0.7, while the extinction Angstrom exponent though being negative, was greater than -0.2. Low values of BAE can likely be explained by an increase in the imaginary part of the dust refractive index at 355 nm compared to 532 nm.
Highlights
Africa is one of the major sources of atmospheric dust and numerous campaigns were organized to study the dust properties near the origin source [1,2,3]
Two enhanced observing periods of 7 weeks are considered: MarchApril 2015 when dust originating from the Sahara/Sahel region is dominant and December 2015-January 2016 when dust and carbonaceous aerosols resulting from fire activities are in variable proportion and transported at different altitudes
We hereinafter focus our study on multiwavelength Mie-Raman lidar measurements performed during the first phase of the SHADOW campaign for the period 8 March - 24 April
Summary
Africa is one of the major sources of atmospheric dust and numerous campaigns were organized to study the dust properties near the origin source [1,2,3]. The objective of the experiment is to report the optical, chemical and physical properties of the aerosols as well as the source apportionment in a location where aerosol loading can be very large and aerosol type depends on the season. We hereinafter focus our study on multiwavelength Mie-Raman lidar measurements performed during the first phase of the SHADOW campaign for the period 8 March - 24 April. During this period approximately 40 day- and night-time measurement sessions were performed and numerous strong dust episodes were observed
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