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Eduardo Landulfo, Alexandros Papayannis, Ani Sobral Torres, Sandro Toshio Uehara, Lucila Maria Viola Pozzetti, Caio Alencar de Matos, Patricia Sawamura, Walter Morinobu Nakaema, and Wellington de Jesus

Abstract

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.

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Thierry Leblanc, I. Stuart McDermid, and Robin A. Aspey

40% of that responsible from CO 2 increases over the same period. The resulting lower-stratospheric cooling would be of the same order of magnitude as that caused by changes in ozone concentrations. This sensitivity of the earth’s radiative balance to water vapor variations requires high-accuracy water vapor measurements (typically 3%–10%) if one wants to fully understand and properly quantify and predict future water vapor–related radiative and chemical processes that impact climate change. A

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Ulrich Löhnert, S. Crewell, O. Krasnov, E. O’Connor, and H. Russchenberg

the forward model to changes in x , whereby 𝗞 i is recalculated for each iteration. The forward model F transforms from the state space ( x ) to the measurement space ( y ) in a straightforward way. For example, given a space vector at a certain iteration x i , F calculates TB by applying the radiative transfer operator (RTO) at the HATPRO frequencies and, in the cloudy case only, Z by assuming a specified Z –LWC power-law relationship of the form Z = a LWC b . Thus, the forward

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V. Bellantone, I. Carofalo, F. De Tomasi, M. R. Perrone, M. Santese, A. M. Tafuro, and A. Turnone

on the temporal and spatial (vertical and horizontal) distributions as well as chemical composition of the different types of aerosol. Different airborne and ground-based aerosol measurements of a forest fire haze layer over a site in northeastern Greece have instead been used by Formenti et al. (2002) for closure tests and the radiative transfer calculations of the spectral shortwave, downwelling irradiance at the surface. Regular measurements by ground-based particulate matter samplers

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