Abstract
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.
Highlights
Air pollution has become one of the major environmental problems around the world
We present measurements of NO2 and HCHO vertical profiles using ground-based MAX-DOAS, while aerosol and O3 profiles in Shanghai were measured using lidar from 5 to 23 May 2016
Accurate aerosol extinction profiles were found to be very important for the retrieval of NO2 and HCHO vertical distribution
Summary
Air pollution has become one of the major environmental problems around the world It is serious in China due to the rapid development of the economy and industrialization. There is a lack of observation for NOx and HCHO vertical distribution in order to investigate the O3 formation and atmospheric chemistry in the lower troposphere. Aerosols, fine particles, are one of the major air pollutants in China. They play a key role in the Earth’s climate and weather system. Aerosol vertical distribution obtained from lidar measurements is useful for the validation of MAX-DOAS retrieval of aerosol extinction profiles (Irie et al, 2008; Lee et al, 2011). Fluxes of ozone were calculated from WRF-Chem simula- 2.1.2 HEIPRO algorithm description and retrieval tions to estimate the ozone production at different altitudes
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