Analysis of temporal and spatial variation characteristics of NO2 pollutants in Guangdong-Hong Kong-Macao Greater Bay Area based on Sentinel-5P satellite data

The TROPOMI (TROPOspheric Monitoring Instrument) on the Sentinel-5Precursor (also known as sentinel-5p) had emerged as base data for spatial analysis of regional NO2 pollution due to its excellent temporal and spatial resolution. Considering the lack of application analysis based on Sentinel-5P NO2 concentration products in Guangdong, Hong Kong and Macao Bay Area (GBA) at present, based on the latest tropospheric NO2 vertical column concentration (troNO2) data produced by TROPOMI, this paper analyzed the distribution and change characteristics of atmospheric NO2 pollutants in recent 2years through Google Earth Engine platform. The results showed that: 1) the troNO2 retrieved by TROPOMI had a high correlation with the monitoring value of surface NO2 concentration, and the inversion product can reflect the real NO2 pollution on the ground; 2) the concentration distribution of troNO2 in GBA showed a significant circle structure: the area of high NO2 density was about 4468km2, accounting for 8% of the total area of GBA, and the area of low NO2 density was about 25331km2, accounting for more than 45%;3) the troNO2 over GBA was characterized by "high in winter and low in summer, and excessive in spring and Autumn"; 4) the impact factor analysis showed that the human activities intensity (DNB, nighttime light), vegetation status (NDVI, vegetation index) and terrain factor (DEM, elevation) had strong correlation with the troNO2. The results of this study can assist the government and policymakers to make more targeted policies to implement NO2 emission reduction and improve air quality.