27 Apr 2023
 | 27 Apr 2023
Status: this preprint is open for discussion.

Enhanced net CO2 exchange of a semi-deciduous forest in the southern Amazon due to diffuse radiation from biomass burning

Simone Rodrigues, Glauber Cirino, Demerval Moreira, Rafael Palácios, José Nogueira, Maria Isabel Vitorino, and George Vourlitis

Abstract. Atmospheric processes and climate are closely linked to the carbon cycle in the Amazon region as a consequence of the strong biosphere-atmosphere coupling. The radiative effects of aerosols and clouds are still unknown for a wide variety of species and types of vegetation present in Amazonian biomes. This study examines the effects of atmospheric aerosols on solar radiation and their effects on Net Ecosystem Exchange (NEE) in an area of semideciduous tropical forest in the North of Mato Grosso State. Our results show a reduction in the NEE with a decrease in incident solar radiation of ≈ 40 % and relative irradiance between 1.10–0.67. However, an average increase of 35–70 % in NEE was observed when pollution levels (Aerosol Optical Depth) were above ≈ 1.25. The increase NEE was attributed to the increase of up to 60 % in the diffuse fraction of Photosynthetically Active Radiation. These results were mainly attributable to the biomass burning organic aerosols from fires. Important influences on temperature and relative humidity of the air, induced by the interaction between solar radiation and high aerosol load in the observation area, were also noticed; an average cooling of ≈ 3.0 °C and 10 %, respectively. Given the long-distance transport of aerosols emitted by burning biomass, significant changes in CO2 flux can occur over large areas of the Amazon, with important effects on the potential for CO2 absorption on ecosystems of semideciduous forests distributed in the region.

Simone Rodrigues et al.

Status: open (until 08 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-684', Anonymous Referee #1, 29 May 2023 reply
  • RC2: 'Comment on egusphere-2023-684', Anonymous Referee #2, 30 May 2023 reply

Simone Rodrigues et al.

Data sets

Brazil-FluxMet-Stf Glauber Cirino, George Vourlitis, Simone Silva, and Rafael Palácios

Simone Rodrigues et al.


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Short summary
The radiative effects of atmospheric particles are still unknown for a wide variety of species and types of vegetation present in Amazonian biomes. We examined the effects of aerosols on solar radiation and their impacts on photosynthesis in an area of semideciduous forest in the southern Amazon basin. Under highly smoky sky conditions, our results show substantial photosynthetic interruption (20–70 %), attributed specially to the decrease in the solar radiation and leaf canopy temperature.