Articles | Volume 17, issue 23
Research article
01 Dec 2017
Research article |  | 01 Dec 2017

Observations of the vertical distributions of summertime atmospheric pollutants and the corresponding ozone production in Shanghai, China

Chengzhi Xing, Cheng Liu, Shanshan Wang, Ka Lok Chan, Yang Gao, Xin Huang, Wenjing Su, Chengxin Zhang, Yunsheng Dong, Guangqiang Fan, Tianshu Zhang, Zhenyi Chen, Qihou Hu, Hang Su, Zhouqing Xie, and Jianguo Liu

Abstract. Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China, during May 2016 to investigate the vertical distribution of summertime atmospheric pollutants. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori profile demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. Tropospheric NO2 vertical column densities (VCDs) measured with MAX-DOAS show a good agreement with OMI satellite observations with a Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height and horizontal and vertical wind field information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground level and upper altitudes are not directly related to horizontal and vertical transportation. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

Short summary
Vertical profiles of the aerosol extinction coefficient and NO2 and HCHO concentrations were retrieved from MAX-DOAS measurement, while vertical distribution of O3 was obtained using ozone lidar. The measured O3 vertical distribution indicates that the ozone production not only occurs at surface level but also at higher altitudes (about 1.1 km), which are not directly related to horizontal and vertical transportation but are mainly influenced by the abundance of VOCs in the lower troposphere.
Final-revised paper