Spatio-temporal distribution of air pollutants and their relationship with land surface temperature over Delhi and its surroundings, India

Air pollution is an important environmental issue prevailing in the urban landscape of Delhi, the capital city of India which is the 2^nd most populous city and most polluted city in the world. The air pollution and land surface temperature (LST) are the most prominent environmental issues in the urban areas. However, there is no comprehensive analysis of the relationship between LST and air pollutants. The objective of the present study is to investigate: (a) the spatio-temporal distribution of LST (diurnal) and the criteria pollutants of carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), particle matter (PM_2.5, PM₁₀) and Sulphur dioxide (SO₂) and (b) the relationship between LST and air pollutants concentration during different seasons in Delhi and its surroundings during 2003–2023. In this study, Landsat satellite data (ETM and OLI) and MODIS satellite data are used to extract the LST for the period 2003-2023. The satellite-based air pollution data is obtained from TROPOMI and MODIS, and ground-based data are obtained from the Central Pollution Control Board (CPCB) monitoring station. Our result reveals that in the spatio-temporal analysis, the LST has increased significantly while the air pollution increased (decreased) over the period. It is observed that there is a strong relationship between LST and air pollutants during winter among all seasons. SO2 has a significant correlation with LST (R² = 0.74). Additionally, PM_2.5 and PM₁₀ are identified as the main air pollutants affecting LST variations during the winter season (R² = 0.59 to 0.64). Our results conclude that variation in the LST is not only dependent on its surface properties but also on the associated meteorological conditions. The findings of this study have significant implications for future scientific research as this study provides the integration of effective mitigation strategies to combat the challenges of increasing LST and air pollution in urban areas.