Atmospheric pollutants in Rosario, Argentina analysed through remote sensing: Wildfires and COVID-19 lockdown effects

Abstract

Spatial-temporal dynamics of atmospheric pollutants can be analysed by space-based observations, contributing to environmental management and public health interventions. The influence of wildfires and anthropogenic activities on air quality is studied for the city of Rosario and its surroundings, including both urban and non-urban areas. Utilizing advanced satellite-based observations, we assess Aerosol Optical Depth (AOD) and Nitrogen Dioxide (NO2). The study employs Multi-Angle Implementation of Atmospheric Correction (MAIAC) and Moderate Resolution Imaging Spectroradiometer (MODIS) onboard NASA´s Terra and Aqua satellites for AOD analysis. NO2 measurements were derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite. Backward trajectory analysis using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) shows the connection between fire pixels and air masses reaching Rosario. During the COVID-19 lockdown, a period with no significant fire events in the studied region was selected. This provided, for the first time, a baseline on the AOD median value of 0.05 for Rosario city and its surroundings, while NO2 total column median values were close to 3.00 x 10 E15 molecules/cm2. In a business-as-usual scenario, AOD increased by approximately 52.8% (March 2022) up to 111.3% (March 2019). NO2 median values remain almost the same (March 2019) or reached a median value of 3.38 x 10 E15 molecules/cm2 (March 2022). During wildfire events, such as March 2023, AOD surged by around 50.9% to 108.6% compared to the business-as-usual scenario (March 2019 and March 2022, respectively). NO2 median values ranged from 3.52 x 10 E15 molecules/cm2 (March 2023) to 3.66 x 10 E15 molecules/cm (01/03/2020 to 19/03/2020). NO2 levels correlated with intense fire periods. The analysis provides valuable insights into the complex interplay between natural events, human activities, and air quality dynamics in the region.