Assessment of aerosol optical depth using MAIAC and AERONET data during the 2020 wildfire season in southeastern South America

Abstract

Wildfires are major contributors to air pollution, with significant impacts on regional air quality and public health. The objective of this study is to assess aerosol optical depth (AOD) during the intense 2020 wildfire season in southeastern South America. AOD data were retrieved from the MAIAC/MODIS algorithm and fire data from VIIRS/SUOMI-NPP satellite. The satellite AOD was correlated with AERONET measurements over Buenos Aires and Montevideo to evaluate satellite performance during fire periods, with higher correlations expected under smoke dominated conditions. Results for the whole area reveal significantly higher AOD values in 2020, with a median of approximately 0.118. Seasonal analysis highlights notable peaks in fire pixel counts during austral spring (median AOD = 0.154) and winter 2020 (median AOD = 0.114). AERONET observations indicated robust correlations with MAIAC AOD during 2020 (R = 0.75). Moderately strong correlations are observed during winter and spring due to elevated aerosol loads from biomass burning. Specifically, Buenos Aires exhibited changes in the AOD-Ångstrom ¨ Exponent relationship, indicating fine-mode aerosol dominance, while Montevideo displayed less pronounced variability but consistent seasonal patterns. These findings show the impact of biomass burning events on air quality, and the utility of integrating satellite and ground-based data for aerosol analysis.