Synergetic measurements of aerosols over São Paulo, Brazil using LIDAR, sunphotometer and satellite data during the dry seasonReportar como inadecuado




Synergetic measurements of aerosols over São Paulo, Brazil using LIDAR, sunphotometer and satellite data during the dry season - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 IPEN-CNEN-SP - Instituto de Pesquisas Energéticas e Nucleares São Paulo 2 NTUA - National Technical University of Athens Athens 3 Instituto de Física da Universidade de São Paulo 4 Instituto de Nacional de Pesquisas Espaciais 5 Instituto de Geofísica

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.





Autor: E. Landulfo - A. Papayannis - P. Artaxo - A. D. A. Castanho - A. Z. De Freitas - R. F. Souza - N. D. Vieira Junior - M. P. M. P.

Fuente: https://hal.archives-ouvertes.fr/



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