Small lidar ratio of dust aerosol observed by Raman-polarization lidar near desert sources.
Opt Express
; 31(10): 16909-16919, 2023 May 08.
Article
em En
| MEDLINE
| ID: mdl-37157759
ABSTRACT
Previous studies have shown that the lidar ratio has a significant influence on the retrieval of the aerosol extinction coefficient via the Fernald method, leading to a large uncertainty in the evaluation of dust radiative forcing. Here, we found that the lidar ratios of dust aerosol were only 18.16 ± 14.23sr, based on Raman-polarization lidar measurements in Dunhuang (94.6°E, 40.1°N) in April of 2022. These ratios are much smaller than other reported results (â¼50 sr) for Asian dust. This finding is also confirmed by some previous results from lidar measurements under different conditions for dust aerosols. The particle depolarization ratio (PDR) at 532â
nm and color ratio (CR, 1064â
nm/532â
nm) of dust aerosols are0.28 ± 0.013 and 0.5-0.6, respectively, indicating that extremely fine nonspherical particles exist. In addition, the dust extinction coefficients at 532â
nm range from2 × 10-4 to 6 × 10-4m-1for such small lidar ratio particles. Combining lidar measurements and model simulation by the T-matrix method, we further reveal that the reason for this phenomenon is mainly due to the relatively small effective radius and weak light absorption of dust particles. Our study provides a new insight into the wide variation in the lidar ratio for dust aerosols, which helps to better explain the impacts of dust aerosols on the climate and environment.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article