**Author details**

268 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

types.

occurrence of higher AOD levels during the dry season for the Midwestern region is

One day backtrajectories calculated for 21 August 2007 using the HYSPLIT model indicated that at 3.5, 4.0 and 4.5 km altitude air masses were advected from regions with intensive biomass burning activities in the Midwestern portion of the Brazilian territory. For the biomass burning episode under investigation in the Midwestern region on 21 August 2007, the AOD and LR at 532 nm was calculated using measurements from the CALIOP sensor and the AERONET sunphotometer installed at Campo Grande. The AOD retrieved by CALIOP sensor spanning from 0.30 to 0.65 and the LR was almost constant at 70 sr. The AERONET provides on the same day mean values of AOD and AE of 0.2 and 1.67, respectively, both values higher than the median in the August period (AOD = 0.1980.078 and AE = 1.460.09). Such values correspond to fine mode size distribution and high absorption and extinction aerosol types, which is a strong indication of the predominance of biomass burning aerosols in the atmosphere. MODIS data image also provide a strong

basically due to the highest amount of biomass burning loaded in the atmosphere.

indication of biomass burning loaded in the atmosphere in the Midwestern region.

had their optical properties altered due to transport and aging processes [37].

This case study shows that the synergy and combination of analysis using several remote sensing instruments, whether passive or active, results in a better understanding of the aerosol optical properties in the atmosphere. Furthermore, these results show that aerosols produced in different regions can be transported by long-range distances. In this sense, megacities such as the Metropolitan Area of São Paulo, which have a large number of local aerosol sources is subject to the influence of aerosol pollution produced by remote sources.

Daytime CALIPSO trajectory on 21 August 2007 together with the HYSPLIT backtrajectories provide evidences that air masses of biomass burning aerosol were transported towards the Southeastern region of Brazilian territory. However, AOD value of 0.10 and LR value of 40-55 sr indicate that those biomass burning aerosol layers have been undergoing an aging process, absorbing moisture from the atmosphere or even mixing with other aerosol

Air mass trajectories generated by the HYSPLIT model showed that these biomass burning aerosols were transported from the CG region towards the Metropolitan Area of São Paulo, reaching MASP on 23 August 2007 at an altitude range of 3.5 to 4.5 km. The backscatter coefficient profile retrieved by the MSP-Lidar system showed an atmosphere heavily loaded of aerosol trapped within the PBL and also a distinguishable aerosol layer between 3.5 and 5 km of altitude. LR values retrieved by the MSP-Lidar, reaching maximum values of 66 sr, are in agreement with LR values of 55 sr signed by the CALIOP sensor. This LR value of 55 sr indicates the presence of polluted dust aerosol type instead of biomass burning type, though. However, it needs to be taken into account that the closest approach of the CALIPSO satellite was 80 km eastern of the MSP-Lidar site, which can lead to the fact that both instruments were not probing the same air mass parcels. Furthermore, the LR values retrieved from MSP-Lidar system in the whole period of time indicate the presence of several amount of aerosols present in the atmosphere of São Paulo, which can disguise the individual effect of the optical properties from biomass burning aerosols, which may have G. L. Mariano\* *Federal University of Pelotas, UFPEL, Pelotas, Brasil* 

F. J. S. Lopes *São Paulo University, USP, São Paulo, Brasil* 

F. J. S. Lopes and E. Landulfo *Nuclear and Energy Research Institute, IPEN, São Paulo, Brasil* 

E. V. C. Mariano *National Institute for Space Research, INPE, São José dos Campos, Brasil* 
