Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations
Multi-wavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentration profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-11-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/6/3243/2013/amt-6-3243-2013.pdf |
| Summary: | Multi-wavelength depolarization Raman lidar measurements from Magurele,
Romania are used in this study along with simulated mass-extinction
efficiencies to calculate the mass concentration profiles of different
atmospheric components, due to their different depolarization contribution to
the 532 nm backscatter coefficient. Linear particle depolarization ratio
(δ<sup>part</sup>) was computed using the relative amplification factor
and the system-dependent molecular depolarization. The low depolarizing
component was considered as urban/smoke, with a mean δ<sup>part</sup>
of 3%, while for the high depolarizing component (mineral dust) a mean
δ<sup>part</sup> of 35% was assumed.
<br><br>
For this study 11 months of lidar measurements were analysed. Two study cases
are presented in details: one for a typical Saharan dust aerosol intrusion,
10 June 2012 and one for 12 July 2012 when a lofted layer consisting of
biomass burning smoke extended from 3 to 4.5 km height.
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Optical Properties of Aerosols and Clouds software package (OPAC)
classification and conversion factors were used to calculate mass
concentrations. We found that calibrated depolarization measurements are
critical in distinguishing between smoke-reach aerosol during the winter and
dust-reach aerosol during the summer, as well as between elevated aerosol
layers having different origins. Good agreement was found between lidar
retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of
Saharan dust. Our method was also compared against LIRIC (The
Lidar/Radiometer Inversion Code) and very small differences were observed. |
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| ISSN: | 1867-1381 1867-8548 |