Concentrations, optical and radiative properties of carbonaceous aerosols over urban Lanzhou, a typical valley city: Results from in-situ observations and numerical model

• Published in: Atmospheric environment (1994) Vol. 213; pp. 470 - 484
• Main Authors: Zhao, Suping, Yu, Ye, Yin, Daiying, Yu, Zhousuo, Dong, Longxiang, Mao, Zhuliang, He, Jianjun, Yang, Jiancai, Li, Ping, Qin, Dahe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.09.2019
• Subjects: Black carbon; OPAC; Optical properties; Radiative effects; SBDART; Urban valley; Urban valley; SBDART; Black carbon; Optical properties; OPAC; Radiative effects
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2019.06.046

The concentrations, optical and radiative effects of carbonaceous aerosols were essential to studies of the climatic, environmental and health effects. The previous studies less combined numerical simulation with in-situ observations, especially for the aerosol vertical profiles. In this study, we off-line measured vertical profiles of submicron black carbon (BC) aerosols and on-line obtained aerosol optical properties over urban Lanzhou during 26 December 2017 to 11 January 2018. The BC optical properties and radiative effects were evaluated using Optical Properties of Aerosols and Clouds (OPAC) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) models. The absorption and scattering coefficients and optical depth of BC aerosols ranged from 9 to 83 M m−1, 3–24 M m−1 and 0.02 to 0.2 respectively, which in average accounted for 50%, 3% and 11% of the optical properties of total aerosols during the study period. BC aerosol radiative forcing (ARF) within ATMOS (top-surface) varying from 16.6 to 108.8 W m−2 accounted for 17.3%–97.4% of total aerosols ARF with an average of 66.6%, and the percentages increased significantly as BC concentrations increased during the period. The mean atmospheric heating rate (AHR) induced by BC aerosols was 1.94 K day−1 ranging from 0.46 to 3.03 K day−1 during the study period. This study contributes to understanding the impacts of light-absorbing aerosols on climate and haze pollution in an urban valley. •BC optical properties were evaluated using OPAC model.•BC radiative forcing was evaluated using SBDART model.•Besides BC, other light-absorbing aerosols increased during high pollution episodes.•The mean heating rate induced by BC aerosols was 1.9 K day−1 over urban Lanzhou.