SPATIO-TEMPORAL VARIATION OF TROPOSPHERIC NITROGEN DIOXIDE (NO2) OVER WEST AFRICA

Abstract

Emissions of Nitrogen dioxide from biomass burning, soil microbial processes, anthropogenic and gas flaring activities over West Africa play major roles in local, regional and global air quality. This study investigates the spatio-temporal trend of NO2 using remotely sensed Ozone Monitoring Instrument (OMI) data between 2005 to 2014. An average of 2.624±0.04x1015 molec/cm2 with a decade increase of 27% was discovered in the course of the study. The increase in the pollutant over this region is linked to biomass burning, anthropogenic activities like vehicular emission, increase in industrial and agricultural activities,etc. The spatio-temporal trend analysis showed significant decline in NO2 over areas where biomass burning was the main driver of NO2 variability and a significant increase in areas where urban emissions were main drivers. The observed seasonality of NO2 is associated with change in meteorological conditions and seasonal cycles of anthropogenic emissions. The analysis reveal a monthly peak in December followed by January largely linked to meteorological conditions and anthropogenic emissions from crop residue and biomass burning, and low concentration is mostly attributed to meteorological conditions.