Long term measurements of aerosol radiative forcing in Amazonia
Paulo
Artaxo, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil, artaxo@if.usp.br
(Presenting)
Aline
S.
Procopio, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil, aline@if.usp.br
Carlos
Pires, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil, capjr@if.usp.br
Melina
M. A.
Paixão, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil, melina@if.usp.br
Alejandro
Duarte, Universidade Federal do Acre, alejandro@ufac.br
Brent
Holben, NASA Goddard Space Flight Center, brent@aeronet.gsfc.nasa.gov
Joel
Schaefer, NASA Goddard Space Flight Center, joel.schafer@gsfc.nasa.gov
The AERONET network of sun-photometers is measuring aerosol optical thickness (AOT) and radiation fluxes in 6 LBA sites: Santarem, Balbina, Rondonia, Alta Floresta, Rio Branco, and Cuiabá. During the wet season, very low atmospheric aerosol loading is observed, with an average AOT of 0.1 at 500 nanometers. During the dry season, very high atmospheric aerosol loading were observed, with values of AOT up to 3 at 500 nm measured in several sites. These high aerosol loading have several effects to the ecosystem, one of them is the significant drop in surface radiation fluxes. Instantaneous fluxes of up to -300 watts per square meters (w/m2) were observed in Alta Floresta e Rondonia. Average dry season values for 7 years of -28 w/m2 were modeled, a value that bring significant changes in the atmospheric radiation budget in large areas of Amazonia. The high aerosol loading enhances diffuse radiation while reduces direct fluxes, in the critical region of photosynthetic radiation. This affects the efficiency of photosynthesis, and the carbon uptake by the Amazonian forest.