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Journal of Geodesy and Geoinformation Science ›› 2020, Vol. 3 ›› Issue (4): 1-13.doi: 10.11947/j.JGGS.2020.0401

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MAX-DOAS and OMI Measurements of Tropospheric NO2 and HCHO over Eastern China

Ka-Lok CHAN1(),Zhuoru WANG1,Aijun DING2,Klaus-Peter HEUE1,Nan HAO3,Mark WENIG4   

  1. 1. Remote Sensing Technology Institute (IMF), German Aerospace Center (DLR), Oberpfaffenhofen 82234, Germany
    2. School of Atmospheric Sciences, Nanjing University, Nanjing 210000, China
    3. European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Darmstadt 64283, Germany
    4. Meteorological Institute, Ludwig-Maximilians-Universität München, München 80331, Germany
  • Received:2020-10-11 Accepted:2020-11-20 Online:2020-12-20 Published:2021-01-15
  • About author:Ka-Lok CHAN (1987—), male, research scientist, majors in remote sensing measurements of atmospheric trace species.E-mail: ka.chan@dlr.de
  • Supported by:
    ESA-MOST Dragon 4 Cooperation Programme(DRAGON 4 ID: 32271_3)

Abstract:

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 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. 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. The 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 does not show a strong spatial correlation with the OMI HCHO observations. The result shows 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.

Key words: MAX-DOAS; OMI; NO2; formaldehyde; pollution transport