A synchronous observation of enhanced aerosol and NO2 over Beijing, China, in winter 2015

Zhenyi Chen; Cheng Liu; Wenqing Liu; Tianshu Zhang; Jin Xu

doi:10.1016/j.scitotenv.2016.09.189

A synchronous observation of enhanced aerosol and NO₂ over Beijing, China, in winter 2015

Sci Total Environ. 2017 Jan 1:575:429-436. doi: 10.1016/j.scitotenv.2016.09.189. Epub 2016 Oct 14.

Authors

Zhenyi Chen¹, Cheng Liu², Wenqing Liu¹, Tianshu Zhang¹, Jin Xu¹

Affiliations

¹ Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
² Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China; CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences，Xiamen 361021, China. Electronic address: chliu81@ustc.edu.cn.

PMID: 27750139
DOI: 10.1016/j.scitotenv.2016.09.189

Abstract

Despite extensive efforts into the characterization of air pollution during the past decade, concurrent real-time characterization of aerosol and NO₂ as well as satellite observation above the urban canopy in the megacity of Beijing has sparsely been performed to date. We conducted a simultaneous real-time measurement of aerosol and NO₂ in urban Beijing in a pollution episode from November 25, 2015 to December 2, 2015. The aerosol extinction coefficient was measured by a 532 Mie lidar and the NO₂ concentration by a Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). The highest aerosol extinction coefficient was 1.55 (±0.16) km^-1 at 532m at a height of 0.27km. The high average aerosol extinction was observed throughout the pollution period, probably due to the favorable static weather conditions under high surface high-pressure system and transportation sources. NO₂ showed similar temporal variations between ground level and 0.3km, whereas a much weaker diurnal evolution was found for NO₂. The boundary layer structures were observed, and the relatively homogeneous mixture maintained the pollution within the layer under 0.5km. Ozone Monitoring Instrument (OMI) NO₂ products based on well-known DOAS trace gas fitting algorithm and WRF-Chem model further illustrated the simultaneous enhancement of NO₂ during the observation period. Backward trajectories suggest that long-range pollution transportation from northwest China contributes more to this pollution event.

Keywords: Aerosol; Lidar; MAX-DOAS; NO(2).