Validation of POLDER-2/PARASOL aerosol products over Beijing area

摘要

This study is devoted to the regional validation of POLDER-2/PARASOL aerosol retrieval scheme over land surfaces against independent automatic sun-photometers located at Beijing and Xianghe sites both included in AERONET(Aerosol Robotic Network)/PHOTONS(PHOtometrie pour le Traitement Operational de Normalisation Satellitaire).Analysis of the AERONET/PHOTONS volume size distributions shows that the fine mode is very well defined with size-cut of about 0.3μm over Beijing area.POLDER-2/PARASOL aerosol optical thickness(AOT)is shown to be quite consistent with the fine fraction of the size distribution(radius 0.3μm).In other words,POLDER-2/PARASOL retrieval over land is mainly sensitive to the anthropogenic aerosols which are known to have important impacts on the climate,environment as well as human health.However,the Angstrom exponent used in the POLDER retrieval algorithm is much higher than the statistic of the AERONET/PHOTONS measurements over Beijing.Thus the derived AOT have been underestimated and the Angstrom exponents have been overestimated.