Fire Hotspot and Aerosol Climatology Observation over South Asia Using Satellite Data

Aerosol particulate pollution is a significant environmental problem in South Asia, thereby impacting the region’s climate, air quality and human health. Daily active fire occurrences and air quality from the SNPP VIIRS are used to analyse the trend of fire occurrences and aerosol particulate pollution over the South Asia region during 2013–2022. The study examines trends in fire occurrences throughout the region which shows an increasing trend over India, Nepal, Pakistan and Myanmar. Notably, high fire occurrences are observed during the Spring, with high fire density over Myanmar and North-East India and during Autumn in western Indo Gangetic Plain (IGP) and in winter over central IGP. The study also explores the long-term aerosol loading over the South Asia region where it is observed that the average value of Aerosol Optical Depth (AOD) in Spring is highest over Northeast India and western Myanmar (0.87), western IGP (0.72) during Winter over central IGP (0.67). The sources of these elevated aerosol pollution are mainly anthropogenic and natural fires, industrial emissions and vehicular pollution. The decadal analysis shows that the trend of fire occurrences increased by +5% over India, followed by +3.86% over Pakistan and 1.66% over Sri Lanka. This is the main sources of enhancement of aerosol pollution, which is depicted in the increase of AOD over India by +3.20%, followed by +0.33% over Pakistan and 4.36% over Nepal over the time period of 10 years (2013–2022). From the climatological long-term observation, it is established that there exists a continuous aerosol pollution source (hotspot) due to fire activity over the sub-regions of western Indo-Gangetic Plain (IGP), central IGP, Part of NE India and Western Myanmar and central eastern region of India. These hotspots often coincide with regions of intense fire activity, with both natural and human-induced fires contributing to aerosol pollution. These findings shed light on the critical periods when fire management and prevention efforts are most needed and also provide a holistic perspective on aerosol pollution in South Asia, contributing vital knowledge regarding fire trends, aerosol distribution and hotspot identification.