Aerosol profiling with lidar in the Amazon Basin during the wet and dry season
For the first time, multiwavelength polarization Raman lidar observations of optical and microphysical particle properties over the Amazon Basin are presented. the fully automated advanced Raman lidar was deployed 60 km north of Manaus, Brazil (2.5 degrees S, 60 degrees W) in the Amazon rain forest from January to November 2008. the measurements thus cover both the wet season (Dec-June) and the dry or burning season (July-Nov). Two cases studies of young and aged smoke plumes are discussed in terms of spectrally resolved optical properties (355, 532, and 1064 nm) and further lidar products such as particle effective radius and single-scattering albedo. These measurement examples confirm that biomass burning aerosols show a broad spectrum of optical, microphysical, and chemical properties. the statistical analysis of the entire measurement period revealed strong differences between the pristine wet and the polluted dry season. African smoke and dust advection frequently interrupt the pristine phases during the wet season. Compared to pristine wet season conditions, the particle scattering coefficients in the lowermost 2 km of the atmosphere were found to be enhanced, on average, by a factor of 4 during periods of African aerosol intrusion and by a factor of 6 during the dry (burning) season. Under pristine conditions, the particle extinction coefficients and optical depth for 532 nm wavelength were frequently as low as 10-30 Mm(-1) and <0.05, respectively. During the dry season, biomass burning smoke plumes reached to 3-5 km height and caused a mean optical depth at 532 nm of 0.26. On average during that season, particle extinction coefficients (532 nm) were of the order of 100 Mm(-1) in the main pollution layer (up to 2 km height). Angstrom exponents were mainly between 1.0 and 1.5, and the majority of the observed lidar ratios were between 50-80 sr. ; National Institute for Amazonia Research (INPA) ; AMAZE-08 team ; European Union (FP7) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; EU FP6 project EUCAARI ; Leibniz Inst Tropospher Res, DE-04318 Leipzig, Germany ; NASA, Langley Res Ctr, Sci Syst & Applicat Inc, Hampton, VA 23665 USA ; Univ São Paulo, Inst Phys, São Paulo, Brazil ; Universidade Federal de São Paulo, Dept Earth & Nat Sci, Diadema, Brazil ; Univ State Amazonas, Manaus, Amazonas, Brazil ; Universidade Federal de São Paulo, Dept Earth & Nat Sci, Diadema, Brazil ; European Union (FP7): 036833-2 ; FAPESP: 2008/58100-2 ; EU FP6 project EUCAARI: 34684 ; Web of Science