Synergetic measurements of aerosols over São Paulo, Brazil using LIDAR, sunphotometer and satellite data during the dry season E. Landulfo1, A. Papayannis2, P. Artaxo3, A. D. A. Castanho3, A. Z. de Freitas1, R. F. Souza1, N. D. Vieira Junior1, M. P. M. P. Jorge4, O. R. Sánchez-Ccoyllo5, and D. S. Moreira5 1Instituto de Pesquisas Energéticas e Nucleares, São Paulo, Brazil 2National Technical University of Athens, Athens, Greece 3Instituto de Física da Universidade de São Paulo, São Paulo, Brazil 4Instituto de Nacional de Pesquisas Espaciais, São José dos Campos, Brazil 5Instituto de Geofísica, Astronomia e Ciências Atmosféricas da Universidade de São Paulo, São Paulo, Brazil
Abstract. A backscattering LIDAR system, the first of this kind in Brazil, has been set-up in a
suburban area in the city of São Paulo (23º33' S, 46º44' W) to provide the vertical
profile of the aerosol backscatter coefficient at 532 nm up to an altitude of
4-6 km above sea level (asl). The measurements have been carried out during the second half of the
so-called Brazilian dry season, September and October 2001 and during the first half of the
dry season in August and September 2002. The LIDAR data are presented and analysed in
synergy with aerosol optical thickness (AOT) measurements obtained by a CIMEL
sun-tracking photometer in the visible spectral region and with satellite measurements
obtained by the MODIS sensor. This synergetic approach has been used, not only to
validate the LIDAR data, but also to derive a typical value (45 sr) of the so-called
extinction-to-backscatter ratio (LIDAR ratio) during the dry season. The satellite data
analysis offers additional information on the spatial distribution of aerosols over Brazil
including the determination of aerosol source regions over the country. The LIDAR data
were also used to retrieve the Planetary Boundary Layer (PBL) height, aerosol layering
and the structure of the lower troposphere over the city of São Paulo. These first LIDAR
measurements over the city of São Paulo during the dry season showed a significant
variability of the AOT in the lower troposphere (0.5-5 km) at 532 nm. It was also found
that the aerosol load is maximized in the 1-3 km height region, although up to
3 km thick aerosol layers were also detected in the 2.5-5.5 km region in certain cases.
Three-dimensional 96-hours air mass back-trajectory analysis was also performed in selected
cases to determine the source regions of aerosols around São Paulo during the dry season.
Citation: Landulfo, E., Papayannis, A., Artaxo, P., Castanho, A. D. A., de Freitas, A. Z., Souza, R. F., Vieira Junior, N. D., Jorge, M. P. M. P., Sánchez-Ccoyllo, O. R., and Moreira, D. S.: Synergetic measurements of aerosols over São Paulo, Brazil using LIDAR, sunphotometer and satellite data during the dry season, Atmos. Chem. Phys., 3, 1523-1539, doi:10.5194/acp-3-1523-2003, 2003.