Abstract
Despite a number of studies on biomass burning (BB) emissions in the atmosphere, observation of the associated aerosols and pollutants requires continuous efforts. Brazil, and more broadly Latin America, is one of the most important seasonal sources of BB, particularly in the Amazon region. Uncertainty about aerosol loading in the source regions is a limiting factor in terms of understanding the role of aerosols in climate modelling. In the present work, we investigated the Amazon BB episode that occurred during August 2019 and made the international headlines, especially when the smoke plumes plunged distant cities such as São Paulo into darkness. Here, we used satellite and ground-based observations at different locations to investigate the long-range transport of aerosol plumes generated by the Amazon fires during the study period. The monitoring of BB activity was carried out using fire related pixel count from the moderate resolution imaging spectroradiometer (MODIS) onboard the Aqua and Terra platforms, while the distribution of carbon monoxide (CO) concentrations and total columns were obtained from the infrared atmospheric sounding interferometer (IASI) onboard the METOP-A and METOP-B satellites. In addition, AERONET sun-photometers as well as the MODIS instrument made aerosol optical depth (AOD) measurements over the study region. Our datasets are consistent with each other and highlight AOD and CO variations and long-range transport of the fire plume from the source regions in the Amazon basin. We used the Lagrangian transport model FLEXPART (FLEXible PARTicle) to simulate backward dispersion, which showed good agreement with satellite and ground measurements observed over the study area. The increase in Rossby wave activity during the 2019 austral winter the Southern Hemisphere may have contributed to increasing the efficiency of large-scale transport of aerosol plumes generated by the Amazon fires during the study period.
Highlights
Carbonaceous aerosols constitute the major component of suspended particulate matter (PM)
We present Carbon monoxide (CO), aerosol optical depth (AOD), and fire distributions derived from infrared atmospheric sounding interferometer (IASI) and moderate resolution imaging spectroradiometer (MODIS) observations over the study area (Southern America, Atlantic, Southern Africa and South-West of the Indian Ocean, see Figure 1) for the study period, August 2019
This suggests that, during the 2019 austral winter, the Southern Hemisphere (SH) was subjected to an increase in Rossby wave activity that may have contributed to increasing the efficiency of large-scale transport of aerosol plumes generated by the Amazon fires during the study period
Summary
Carbonaceous aerosols constitute the major component of suspended particulate matter (PM). The bulk of BB activities in Southern America are widespread within the so-called “arc of deforestation” which refers to the region where the agricultural frontier extends into the forest and has the highest rates of deforestation in the South America. This region traverses the southern and eastern edges of the Amazon basin. Several questions on distribution of the aerosols and pollutants injected into the atmosphere, together with the associated long-range transport processes during the Southern America BB season require collaborative initiatives and multi-instrumental investigations.
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