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@Article{CecchiniMCMWFTSAMA:2016:ImMaPo,
               author = "Cecchini, Micael Amore and Machado, Luiz Augusto Toledo and 
                         Comstock, Jennifer M. and Mei, Fan and Wang, Jian and Fan, Jiwen 
                         and Tomlinson, Jason M. and Schmid, Beat and Albrecht, Rachel and 
                         Martin, Scot T. and Artaxo, Paulo",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Pacific Northwest 
                         National Laboratory} and {Pacific Northwest National Laboratory} 
                         and {Brookhaven National Laboratory} and {Pacific Northwest 
                         National Laboratory} and {Pacific Northwest National Laboratory} 
                         and {Pacific Northwest National Laboratory} and {Universidade de 
                         S{\~a}o Paulo (USP)} and {Harvard University} and {Universidade 
                         de S{\~a}o Paulo (USP)}",
                title = "Impacts of the Manaus pollution plume on the microphysical 
                         properties of Amazonian warm-phase clouds in the wet season",
              journal = "Atmospheric Chemistry and Physics",
                 year = "2016",
               volume = "16",
                pages = "7029--7041",
             abstract = "The remote atmosphere over the Amazon can be similar to oceanic 
                         regions in terms of aerosol conditions and cloud type formations. 
                         This is especially true during the wet season. The main 
                         aerosol-related disturbances over the Amazon have both natural 
                         sources, such as dust transport from Africa, and anthropogenic 
                         sources, such as biomass burning or urban pollution. The present 
                         work considers the impacts of the latter on the microphysical 
                         properties of warm-phase clouds by analysing observations of the 
                         interactions between the Manaus pollution plume and its 
                         surroundings, as part of the GoAmazon2014/5 Experiment. The 
                         analysed period corresponds to the wet season (specifically from 
                         February to March 2014 and corresponding to the first Intensive 
                         Operating Period (IOP1) of GoAmazon2014/5). The droplet size 
                         distributions reported are in the range 1 Ám \≤ D \≤ 
                         50 Ám in order to capture the processes leading up to the 
                         precipitation formation. The wet season largely presents a clean 
                         background atmosphere characterized by frequent rain showers. As 
                         such, the contrast between background clouds and those affected by 
                         the Manaus pollution can be observed and detailed. The focus is on 
                         the characteristics of the initial microphysical properties in 
                         cumulus clouds predominantly at their early stages. The 
                         pollution-affected clouds are found to have smaller effective 
                         diameters and higher droplet number concentrations. The 
                         differences range from 10 to 40 % for the effective diameter and 
                         are as high as 1000 % for droplet concentration for the same 
                         vertical levels. The growth rates of droplets with altitude are 
                         slower for pollution-affected clouds (2.90 compared to 5.59 Ám 
                         km\−1 ), as explained by the absence of bigger droplets at 
                         the onset of cloud development. Clouds under background conditions 
                         have higher concentrations of larger droplets (> 20 Ám) near the 
                         cloud base, which would contribute significantly to the growth 
                         rates through the collisioncoalescence process. The overall shape 
                         of the droplet size distribution (DSD) does not appear to be 
                         predominantly determined by updraught strength, especially beyond 
                         the 20 Ám range. The aerosol conditions play a major role in that 
                         case. However, the updraughts modulate the DSD concentrations and 
                         are responsible for the vertical transport of water in the cloud. 
                         The larger droplets found in background clouds are associated with 
                         weak water vapour competition and a bimodal distribution of 
                         droplet sizes in the lower levels of the cloud, which enables an 
                         earlier initiation of the collisioncoalescence process. This study 
                         shows that the pollution produced by Manaus significantly affects 
                         warmphase microphysical properties of the surrounding clouds by 
                         changing the initial DSD formation. The corresponding effects on 
                         ice-phase processes and precipitation formation will be the focus 
                         of future endeavours.",
                  doi = "10.5194/acp-16-7029-2016",
                  url = "http://dx.doi.org/10.5194/acp-16-7029-2016",
                 issn = "1680-7316 and 1680-7324",
             language = "en",
           targetfile = "cecchini_impacts.pdf",
        urlaccessdate = "27 nov. 2020"
}


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