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MAX-DOAS measurements of tropospheric NO₂ and HCHO in Nanjing and a comparison to ozone monitoring instrument observations

Chan, Ka Lok and Wang, Zhuoru and Ding, Aijun and Heue, Klaus-Peter and Shen, Yicheng and Wang, Jing and Zhang, Feng and Shi, Yining and Hao, Nan and Wenig, Mark (2019) MAX-DOAS measurements of tropospheric NO₂ and HCHO in Nanjing and a comparison to ozone monitoring instrument observations. Atmospheric Chemistry and Physics, 19 (15), pp. 10051-10071. Copernicus Publications. ISSN 1680-7316.

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Official URL: https://www.atmos-chem-phys.net/19/10051/2019/


In this paper, we present long-term observations of atmospheric nitrogen dioxide (NO2) and formaldehyde (HCHO) in Nanjing using a Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument. Ground-based MAX-DOAS measurements were performed from April 2013 to February 2017. The MAX-DOAS measurements of NO2 and HCHO vertical column densities (VCDs) are used to validate ozone monitoring instrument (OMI) satellite observations over Nanjing. The comparison shows that the OMI observations of NO2 correlate well with the MAX-DOAS data with Pearson correlation coefficient (R) of 0.91. However, OMI observations are on average a factor of 3 lower than the MAX-DOAS measurements. Replacing the a priori NO2 profiles by the MAX-DOAS profiles in the OMI NO2 VCD retrieval would increase the OMI NO2 VCDs by ∼30 % with correlation nearly unchanged. The comparison result of MAX-DOAS and OMI observations of HCHO VCD shows a good agreement with R of 0.75 and the slope of the regression line is 0.99. An age-weighted backward-propagation approach is applied to the MAX-DOAS measurements of NO2 and HCHO to reconstruct the spatial distribution of NO2 and HCHO over the Yangtze River Delta during summer and winter time. The reconstructed NO2 fields show a distinct agreement with OMI satellite observations. However, due to the short atmospheric lifetime of HCHO, the backward-propagated HCHO data do not show a strong spatial correlation with the OMI HCHO observations. The result shows that the MAX-DOAS measurements are sensitive to the air pollution transportation in the Yangtze River Delta, indicating the air quality in Nanjing is significantly influenced by regional transportation of air pollutants. The MAX-DOAS data are also used to evaluate the effectiveness of air pollution control measures implemented during the Youth Olympic Games 2014. The MAX-DOAS data show a significant reduction of ambient aerosol, NO2 and HCHO (30 %–50 %) during the Youth Olympic Games. Our results provide a better understanding of the transportation and sources of pollutants over the Yangtze River Delta as well as the effect of emission control measures during large international events, which are important for the future design of air pollution control policies.

Item URL in elib:https://elib.dlr.de/129097/
Document Type:Article
Title:MAX-DOAS measurements of tropospheric NO₂ and HCHO in Nanjing and a comparison to ozone monitoring instrument observations
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Chan, Ka LokKa.Chan (at) dlr.deUNSPECIFIED
Ding, AijunNanjing UniversityUNSPECIFIED
Heue, Klaus-PeterKlaus-Peter.Heue (at) dlr.dehttps://orcid.org/0000-0001-8823-7712
Shen, YichengNanjing UniversityUNSPECIFIED
Wang, JingNanjing University of Information Science and TechnologyUNSPECIFIED
Zhang, FengNanjing University of Information Science and TechnologyUNSPECIFIED
Shi, YiningNanjing University of Information Science and TechnologyUNSPECIFIED
Date:9 August 2019
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 10051-10071
Publisher:Copernicus Publications
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):Vorhaben Spectroscopic Methods in Remote Sensing (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Chan, Ka Lok
Deposited On:23 Sep 2019 12:18
Last Modified:07 Oct 2019 13:02

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