Publication Date:
2018
Description:
〈b〉Interrelations between surface, boundary layer, and columnar
aerosol properties over a continental urban site〈/b〉〈br〉
Dongxiang Wang, Dominika Szczepanik, and Iwona S. Stachlewska〈br〉
Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1219,2018〈br〉
〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉
〈p〉PollyXT Raman Polarization Lidar observations were performed at the Remote Sensing laboratory in Warsaw (52.2109° N, 20.9826° E), Poland, in the framework of the European Aerosol Research Lidar Network (EARLINET) and the Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS). Data collected in July, August and September of 2013, 2015 and 2016 were analysed using the classical Raman approach. In total 202 sets of profiles of the particle extinction and backscatter coefficient, and linear particle depolarization ratio at 355 nm and 532 nm were derived for statistical investigations (EARLINET/ACTRIS Data Base). The main analysis was focused on intensive optical properties obtained within aerosol boundary layer (ABL). The interrelationships of different optical properties inside ABL are discussed for different periods: entire day, nocturnal time and sunrise/sunset time. In addition, the lidar derived boundary layer optical properties were compared with the columnar daytime aerosol properties derived from radiometer (MFR-7, PolandAOD-NET) and photometer (C318, AERONET). Relationships of these and surface in-situ measurements of particulate matter with an aerodynamic diameter 10) and 2.5) (WIOŚ Network) are investigated. Within boundary layer, the lidar derived optical properties (entire day, 202 sets) revealed the mean aerosol optical depth (AOD〈sub〉ABL〈/sub〉) of 0.27 ± 0.17 at 355 nm and 0.15 ± 0.10 at 532 nm; the mean Ångström exponent (ÅE〈sub〉ABL〈/sub〉) of 1.65 ± 0.45; the mean lidar ratio (LR〈sub〉ABL〈/sub〉) of 49 ± 16 sr at 355 nm and 41 ± 15 sr at 532 nm; the mean linear particle depolarization ratio (PLDR〈sub〉ABL〈/sub〉) of 0.02 ± 0.01 at 355 nm and 0.05 ± 0.02 at 532 nm, the mean water vapor mixing ratio (WVMR〈sub〉ABL〈/sub〉) of 8.16 ± 2.40 g/kg. Aerosol composition within ABL was assessed based on the derived properties interpreted with respect to values reported in literature and backward trajectories; it consisted either of pure urban anthropogenic pollution aerosols (~ 60 %), its mixtures with biomass burning aerosols (ABL exhibit positive correlation (~ 0.6), attributed in majority cases to local anthropogenic pollution. LR〈sub〉ABL〈/sub〉 and surface fine to coarse mass ratio (FCMR) presents weak positive-correlation (~ 0.4) at nocturnal time, due to the higher(lower) occurrence of fine(coarse) particles at night. On the contrary, weak negative-correlation (~ −0.3) of LR〈sub〉ABL〈/sub〉 and FCMR are present in sunrise/sunset time, for inverse occurrence of fine and coarse particles. A negative-correlation of PLDR〈sub〉ABL〈/sub〉 and FCMR (~ −0.4 at 355 nm, −0.6 to −0.7 at 532 nm) for all time period and no relation between PLDR〈sub〉ABL〈/sub〉 and ÅE〈sub〉ABL〈/sub〉 (~ 0.05) was found. Relation of AOD〈sub〉ABL〈/sub〉 and PM〈sub〉10〈/sub〉 reveals positive correlation (0.4 355; 0.5 532) for sunrise/sunset time, but no significant correlations found for AOD〈sub〉ABL〈/sub〉 and PM〈sub〉2.5〈/sub〉 (0.26 at 355; 0.16 at 532 nm). In general, a positive correlation of AOD〈sub〉ABL〈/sub〉 and LR〈sub〉ABL〈/sub〉 (stronger pronounced at 355 nm) and a negative correlation ÅE〈sub〉ABL〈/sub〉 and LR〈sub〉ABL〈/sub〉 (stronger pronounced at 532 nm) is observed. The ÅECL values stay roughly between 1.0 and 2.0, while the ÅE〈sub〉ABL〈/sub〉 values range from 0.1 to 2.5, indicating a variety of particle sizes occurring inside ABL during summer and early-autumn period in Warsaw.〈/p〉
Print ISSN:
1680-7367
Electronic ISSN:
1680-7375
Topics:
Geosciences
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