Remote sensing of aerossol with high spacial resolution in amazon region / Sensoriamento remoto de aerossóis em alta resolução espacial na região amazônica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The significant deforestation process in Amazonia results in high levels of aerosols and trace gases emitted to the atmosphere. It is necessary the development of tool that allows a better quantification of the atmospheric aerosol loading and consequently the impact on regional climate, including changes in the regional radiation balance and the mechanisms of cloud formation and development. Aerosol optical properties were investigated through the analysis of the sun-photometer that is part of the Aerosol Robotic Network (AERONET) located in Ji-Paraná (RO, Brazil). Two aerosol optical models, representative of that specific region were defined as a function of the single scattering albedo (0), through the analysis of the real and imaginary refractive indexes and the aerosol size distribution. Taking into account the 676nm wavelength, both models returned single scattering albedo values of 0(1)=0.88 and 0(2)=0.94. A well-established methodology used for urban aerosol studies through the analysis of MODIS (Moderate-Resolution Imaging Spectroradiometer) data was adapted to Amazonia. It has obtained aerosol optical depth (AOD) for the Amazon region, improving the standard spatial resolution of 10 km x 10 km to 1.5 km x 1.5 km with good results. The adapted algorithm takes into account the critical reflectance to provide the appropriate aerosol optical model to be used, in an interactive and dynamical way, reducing the uncertainty in the aerosol optical depth determination with high spatial resolution. The results of the validation analysis showed that the AOD obtained with high spatial resolution and those obtained from the NASA operational product when compared with AERONET data shows very satisfactory results. The high-resolution method developed in this work had a very good agreement compared with the single aerosol optical model for 40% of the analyzed cases. This shows that an important source of uncertainty, the choice of a more appropriate optical model was reduced. The validation of the results done with sun-photometer measurements showed very good agreement, with a regression equation: y= (1,09±0,03)x+(0,03±0,02), with R²=0,80. The cloud contamination issue is reduced with the high-resolution method, but is still an important issue that requires further investigation.

ASSUNTO(S)

climate change mudanças climáticas amazônia sensoriamento remoto aerosol remote sensing aerossóis amazonia

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