Quantitative assessment of spatiotemporal variability in air quality within the Amman-Zarqa urban Area, Jordan

Abstract

Many factors influence the concentration of air pollutants, particularly Carbon Monoxide (CO) and Nitrogen Dioxide (NO₂). This research aims to study the spatiotemporal variability of CO and NO₂ on a monthly basis in 2021 and to investigate the relationship between these gases and both natural and anthropogenic factors across seven districts of the Amman-Zarqa urban environment of Jordan. To understand these relationships using regression analysis and the mean relative difference, the CO and NO₂ data extracted from The TROPOspheric Monitoring Instrument (TROPOMI) which is the satellite instrument on board the Copernicus Sentinel-5 Precursor satellite. The results of the mean relative difference indicated that the spatial concentration of CO in the Zarqa districts is higher than in the Amman districts due to industrial activities and low vegetation cover. In contrast, NO₂ is primarily concentrated in the Marka and Qasaba Amman districts than the other districts, which have the highest traffic and population density in the study area. Regression analysis reveals that while the concentration of CO is positively correlated with Land Surface Temperature (LST), Wind Speed (WS), and Wind Direction (WD), with r² values of approximately 0.62, 0.53, and 0.48 respectively. Conversely, a negative relationship is observed with digital Elevation Model (DEM), Normalized Difference Vegetation Index (NDVI), and Relative Humidity (RH). For NO₂, a weak positive correlation with the Built-Up (BU) index and Normalized Difference Built-Up Index (NDBI) has been noticed, along with a modest negative correlation with LST, DEM, WS, RH, WD, and NDVI.