Inspecting gaseous pollutants and their dynamics in Kathmandu using satellite derived data
DOI:
https://doi.org/10.21138/GF.835Abstract
Air pollution is mostly due to anthropogenic causes degrading the quality of breathable air. The larger dimensions of gaseous pollutants are still challenging to inspect. Satellite data can quantify the concentrations of atmospheric pollutants that are specifically beneficial in understanding air pollution. This paper attempts to understand the air pollutants in the Kathmandu district (Nepal) retrieved from the Sentinel-5P satellite data from 2019 to 2022: by correlating with the weather parameter and vegetation indices, observing the yearly concentrations of the gaseous pollutants over the days of the year and observing their spatial distribution. In the results, temperature showed a predominantly strong positive correlation with methane (CH₄), carbon monoxide (CO) and ozone (O3) and a negative correlation with nitrogen dioxide (NO₂), formaldehyde (HCHO), sulphur dioxide (SO₂) and aerosol. Precipitation was negatively correlated with all the pollutants except the O3. Vegetation indices, Normalised Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), were negatively correlated with most of the gaseous pollutants signifying the importance of the vegetation towards mitigating the gaseous pollutants. Moreover, yearly trends of the gaseous pollutants and the spatial distributions were unique for all the gaseous pollutants. Lowest mean concentrations of the aerosol index, HCHO, NO2 and O3 in different days of 2020 were suggestive towards the impacts of COVID-19 lockdown. In the broader context, proper vegetation and the remedial ways to maintain Kathmandu’s temperature, around the city areas, is likely to moderate the gaseous pollutants in the city. This paper clearly points to the approach in utilising the satellite based data in air pollution inspections.
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