Radiative effects of biomass-burning aerosols on surface solar irradiance in southern Mexico: Evidence from BSRN–AERONET observations

Carabalí G.; Ríos B.; Manríquez-Galindo J.A.; Arellano-Hernández E.J.; Valdés-Barrón M.; Bonifaz-Alfonzo R.; Velasco-Herrera V.M.; González-Cabrera A.E.; Liñán-Abanto R.N.; Riveros-Rosas D.; Estévez H.R. · Journal of Atmospheric and Solar-Terrestrial Physics (2026) · DOI: 10.1016/j.jastp.2026.106977

Resumen

Biomass-burning (BB) aerosols may influence the dry-season radiation budget in tropical fire-prone regions, yet observational evidence of their radiative effects remains scarce in southern Mexico. We analyze collocated BSRN and AERONET observations from SEL (Frontera Comalapa, Chiapas, Mexico) during March–April 2024. AOD500 ranged from 0.070 to 1.396 (mean 0.425 ± 0.223), and the Ångström exponent (440–870 nm) averaged 1.60 ± 0.16, indicating a predominance of fine-mode aerosols consistent with the influence of regional biomass burning. Sky conditions were predominantly clear or mostly clear, representing 75.2% of daytime records. Under clear skies, increasing aerosol loading was associated with a reduction in DNI (S0.1 = −33.4 W m−2, where S0.1 denotes the change per 0.1 increase in AOD500) and a corresponding increase in the diffuse fraction (DHI/GHI; S0.1 = +0.029), while GHI remained statistically unchanged across much of the observed aerosol-loading conditions. Regional analyses of active fires, air-mass trajectories, and fire emissions indicate that high-AOD days at SEL were linked to late-dry-season biomass-burning activity over southern Mexico and northern Central America. Instantaneous radiative forcing estimates were ARFBOA = −63.6 ± 23.0 W m−2 and ARFTOA = −18.7 ± 11.4 W m−2, suggesting atmospheric absorption associated with biomass-burning aerosol conditions. These observations provide a well-constrained regional case study of aerosol-driven redistribution and attenuation of surface solar radiation at a tropical receptor site affected by regional biomass burning in Mesoamerica. Copyright

Instituciones: Universidad Nacional Jorge Basadre Grohmann