Analysis of the tropospheric column nitrogen dioxide over China based on satellite observations during 2008-2017

This study presents an analysis of the atmospheric column nitrogen dioxide (NO2) over China during 2008-2017. Measurements of NO2 columns obtained from the Ozone Monitoring Instrument (OMI) are used to investigate the temporal and spatial dynamics of NO2. Temporal and spatial distributions of NO2 obtained from OMI over China from 2008 to 2017 are presented, and annual changes and trends in the seasonal cycle are shown. The annual mean NO2 columns are found to decrease 13% from 2008 to 2017. NO2 shows significant cyclical seasonal characteristics over China, with maximum values in winter and minimum in summer. In addition, the spatial distribution is unbalanced, the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region, the Yangtze River Delta region and the Pearl River Delta region are found to be highly polluted areas, the NO2 columns in these regions have been declining by 17.6%, 24.5% and 16.7% during 2008-2017 respectively. Yearly variations in the NO2 columns over the four major economic plates are prominent, and there is a maximum in the eastern region and a minimum in the western region during the past decade, these four regions show a downward trend in recent years. Three areas and six groups are important pollution regions, and the NO2 columns over these regions also show decrease trend.