@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 µm \≤ D \≤
50 µm 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 µm
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 µm) 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 µm 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 = "28 abr. 2024"
}