Spectral dependence of aerosol light absorption at an urban and a remote site over the Tibetan Plateau

Chong-Shu Zhu; Jun-Ji Cao; Ta-Feng Hu; Zhen-Xing Shen; Xue-Xi Tie; Hong Huang; Qi-Yuan Wang; Ru-Jin Huang; Zhu-Zi Zhao; Griša Močnik; Anthony D A Hansen

doi:10.1016/j.scitotenv.2017.03.057

Spectral dependence of aerosol light absorption at an urban and a remote site over the Tibetan Plateau

Sci Total Environ. 2017 Jul 15:590-591:14-21. doi: 10.1016/j.scitotenv.2017.03.057. Epub 2017 Mar 9.

Authors

Affiliations

¹ Key Laboratory of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China. Electronic address: chongshu@ieecas.cn.
² Key Laboratory of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China. Electronic address: cao@loess.llqg.ac.cn.
³ Key Laboratory of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
⁴ Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
⁵ Key Laboratory of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
⁶ School of Resource, Environmental and Chemical Engineering, NanChang University, Nanchang 330031, China.
⁷ Research and Development Department, Aerosol d.o.o., 1000 Ljubljana, Slovenia; Condensed Matter Physics Department, Jozef Stefan Institute, 1000 Ljubljana, Slovenia.
⁸ Magee Scientific Corp., Berkeley, CA 94702, USA.

PMID: 28284114
DOI: 10.1016/j.scitotenv.2017.03.057

Abstract

We present a study of aerosol light absorption by using a 7-wavelength Aethalometer model AE33 at an urban site (Lhasa) and a remote site (Lulang) in the Tibetan Plateau. Approximately 5 times greater aerosol absorption values were observed at Lhasa (53±46Mm^-1 at 370nm and 20±18Mm^-1 at 950nm, respectively) in comparison to Lulang (15±19Mm^-1 at 370nm and 4±5Mm^-1 at 950nm, respectively). Black carbon (BC) was the dominant light absorbing aerosol component at all wavelengths. The brown carbon (BrC) absorption at 370nm is 32±15% of the total aerosol absorption at Lulang, whereas it is 8±6% at Lhasa. Higher value of absorption Ångström exponent (AAE, 370-950nm) was obtained for Lulang (1.18) than that for Lhasa (1.04) due to the presence of BrC. The AAEs (370-950nm) of BrC were directly extracted at Lulang (3.8) and Lhasa (3.3). The loading compensation parameters (k) increased with wavelengths for both sites, and lower values were obtained at Lulang than those observed at Lhasa for all wavelengths. This study underlines the relatively high percentage of BrC absorption contribution in remote area compared to urban site over the Tibetan Plateau.

Keywords: Black carbon; Brown carbon; Light absorption; Tibetan plateau.