A four-year lidar-sun photometer aerosol study at São Paulo, Brazil

• Published in: Journal of Atmospheric and Oceanic Technology
• Main Authors: Landulfo, E, Papayannis, A, Torres, AS, Uehara, ST, Pozzetti, LMV, de Matos, CA, Sawamura, P, Nakaema, WM, de Jesus, W
• Format: Conference Object
• Language: English
• Published: AMER METEOROLOGICAL SOC 2008
• Subjects: Engineering; Ocean; Meteorology & Atmospheric Sciences; Aerosol backscattering; Aerosol optical thickness; Aerosol robotic networks; Backscatter coefficients; Cloud base; Cloud properties; Dry and wet; Extinction coefficients; Extinction-to-backscatter ratio; Input values; LIDAR data; Lidar ratio; Lidar systems; Lower troposphere; Phase functions; Planetary boundary layers; Single scattering albedo; Structure and dynamics; Suburban areas; Sun photometers; Sun-tracking; Temporal Database; Vertical profile; Visible spectral regions; Wet season; Acoustic emissions; Atmospheric aerosols; Atmospheric thermodynamics; Backscattering; Electric reactors; Image sensors; Oceanography; Optical radar; Photometers; Photometry; Sun; Atmospherics; absorption; aerosol; aerosol property; boundary layer; conference proceeding; database; lidar; measurement method; photometer; satellite data; troposphere; Brazil; Sao Paulo [Brazil]; South America; Aerosol Robotic Network
• Online Access: http://dspace.lib.ntua.gr/handle/123456789/32104; https://doi.org/10.1175/2007JTECHA984.1

A backscattering lidar system, the first of this kind in Brazil, has been used 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), in a suburban area in the city of São Paulo. The lidar system has been operational since September 2001. The lidar data products were obtained in a 4-yr period (2001-04) and concerned the aerosol optical thickness (AOT), the aerosol backscattering and extinction coefficients at 532 nm, cloud properties (cloud base, thickness), planetary boundary layer (PBL) heights, aerosol layering, and the structure and dynamics of the lower troposphere. The lidar data are presented and analyzed in synergy with AOT measurements obtained by a Cimel sun-tracking photometer in the visible spectral region, not only to validate the lidar data but also to provide an input value of the so-called extinction-to-backscatter ratio [lidar ratio (LR)]. A correlation between the lidar data and the data obtained by a Cimel sun-tracking photometer [belonging to the Aerosol Robotic Network (AERONET)] is being made to set a temporal database of those data that were collected concomitantly and to cross correlate the information gathered by each instrument. The sun photometer data are used to provide AOT values at selected wavelengths and thus to derive the Ångström exponent (AE) values, single scattering albedo (SSA) and phase function values, and LR values. The analysis of these data showed an important trend in the seasonal signature of the LR indicating a change of the predominant type of aerosol between the dry and wet seasons. Thus, during the wet season the LR lidar values are greater (50-60 sr), which indicates that larger absorption by the aerosols takes place during this period. The corresponding AE values range between 1.3 and 2 for both periods. © 2008 American Meteorological Society.