Recent Spatial and Temporal Analysis of Aerosol Optical Depth from MERRA-2 over Borneo Island

Aerosols have been recognized as an important indicator for air quality research, gaining significant attention over recent decades. These complex substances affect not only air quality but also weather and climate. In Malaysia, considerable air pollution issues are often attributed to a substantial amount of aerosols generated by open biomass burning activities. This study analyzes the recent spatial and temporal variations of aerosols in the Malaysian Borneo region from 2019 to 2021, using the aerosol optical depth (AOD) data from MERRA-2. It also clarifies how synoptic meteorological conditions influence pollutant distribution. Additionally, the research examines the impact of biomass burning activities by utilizing daily fire records from FIRMS and employs the HYSPLIT backward air mass trajectory model to identify aerosol emission sources. The highest AOD values were recorded in September 2019, reaching 0.65, 1.40, and 3.08 in the northern, central, and southern regions of Malaysian Borneo, respectively. Overall, AOD levels in the Malaysian Borneo region showed a strong correlation with biomass burning activities, with correlation coefficients ranging from 0.87 to 0.97. This study identified Kalimantan and Sumatra as the two main sources of aerosol pollution. Although the transport of aerosols from burning in Sumatra was less pronounced in northern Malaysian Borneo, significant increases in aerosol levels were observed in the central and southern regions. Stagnant weather conditions were found to be responsible for elevated AOD levels due to short-range transport. The study indicated that aerosols from biomass burning activities dispersed near Malaysian Borneo and were closely associated with synoptic circulation patterns.