Study of the Radiative Effect ...

Study of the Radiative Effect of Smoke in the Southwestern Portion of the Amazon Basin

During the dry season, large amount of aerosol particles is emitted to the atmosphere in the Amazon Basin. Those particles interact with solar radiation through scattering and absorption processes. Both processes reduce the amount of solar irradiance reaching the surface, while the absorption process can heat the aerosol layer and the scattering process can increase the diffuse fraction of solar radiation. The objective of this talk is to present results of a field experiment conducted in the Southwestern portion of the Amazon Basin during the dry season of 2007 (from 24 August to 29 October), at Reserva Biológica do Jaru (-10,19°; -61,87°), a region surrounded of primary rainforest. Measurements of photosynthetically active radiation (PAR) and global and diffuse broad and narrowband irradiance were conducted. PAR measurements were performed at 7 levels inside the canopy. Additional measurements are continuously performed at a 67m height micrometeorological tower to estimate turbulent sensible and latent heat and CO2 fluxes. From the narrowband data, aerosol optical depth was retrieved and during the field experiment, values higher than 2.0 were frequently observed at channel around 670 nm. Reduction of surface turbulent fluxes was observed due to the presence of smoke, although latent heat flux decreased more slowly, thus, evaporative fraction was higher in smokier or cloudier conditions compared to clear sky conditions. Another result is that the smoke layer reduced the frequency of occurrence of sun flecks due to the attenuation of the direct component of the solar radiation and affected the fraction of absorbed PAR by the vegetation.

Presentation Type: 
Invited Presentation
Author 1: 
Marcia Akemi Yamasoe
Author 4: 
Bianca Lobo Silva
Additional Authors: 
no more authors
Author Roles
Corresponding Author: 
Marcia Akemi Yamasoe
Presenting Author: 
Marcia Akemi Yamasoe