Abstract
Abstract. Within this publication, lidar observations of the vertical aerosol distribution above Punta Arenas, Chile (53.2∘ S and 70.9∘ W), which have been performed with the Raman lidar PollyXT from December 2009 to April 2010, are presented. Pristine marine aerosol conditions related to the prevailing westerly circulation dominated the measurements. Lofted aerosol layers could only be observed eight times during the whole measurement period. Two case studies are presented showing long-range transport of smoke from biomass burning in Australia and regionally transported dust from the Patagonian Desert, respectively. The aerosol sources are identified by trajectory analyses with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and FLEXible PARTicle dispersion model (FLEXPART). However, seven of the eight analysed cases with lofted layers show an aerosol optical thickness of less than 0.05. From the lidar observations, a mean planetary boundary layer (PBL) top height of 1150 ± 350 m was determined. An analysis of particle backscatter coefficients confirms that the majority of the aerosol is attributed to the PBL, while the free troposphere is characterized by a very low background aerosol concentration. The ground-based lidar observations at 532 and 1064 nm are supplemented by the Aerosol Robotic Network (AERONET) Sun photometers and the space-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The averaged aerosol optical thickness (AOT) determined by CALIOP was 0.02 ± 0.01 in Punta Arenas from 2009 to 2010.
Highlights
Aerosols might possibly compensate the warming effect of the greenhouse gases in the Earth’s radiation budget within the uncertainties of future climate modelling (Boucher et al, 2013)
The presented study aimed on providing an overview about the vertical aerosol conditions above Punta Arenas
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations, which were utilized to track the long-range transport of aerosol from Australia to Punta Arenas, indicate that a considerable fraction of free-tropospheric aerosol is removed by cloud processes and washout taking place over the Pacific Ocean before it reaches South America
Summary
Aerosols might possibly compensate the warming effect of the greenhouse gases in the Earth’s radiation budget within the uncertainties of future climate modelling (Boucher et al, 2013). Lidar observations of the vertical aerosol distribution above Punta Arenas, Chile (53.2◦ S and 70.9◦ W), are presented as performed during the Aerosol Lidar measurement in Punta Arenas in the frame of Chilean– GermAn cooperation (ALPACA) campaign which took place from December 2009 to April 2010. This location at the southern tip of South America yields an excellent opportunity to study almost clean marine aerosol conditions which are characteristic for the Southern Ocean (SO) because of the absence of continental land masses in the latitudinal belt south of 45◦ S and a constant westerly air flow from the Pacific Ocean (Schneider et al, 2003). A conclusion about the results of ALPACA and an outlook for an upcoming campaign are given at the end
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