@Article{ShillingPFASHLMMSTW:2019:AiObCh,
author = "Shilling, John E. and Pekour, Mikhail S. and Fortner, Edward C.
and Artaxo, Paulo and S{\'a}, Suzane de and Hubbe, John M. and
Longo, Karla M. and Machado, Luiz Augusto Toledo and Martin, Scot
T. and Springston, Stephen R. and Tomlinson, Jason and Wang,
Jian",
affiliation = "{Pacific Northwest National Laboratory} and {Pacific Northwest
National Laboratory} and Center for Aerosol and Cloud Chemistry,
Aerodyne Research and {Universidade de S{\~a}o Paulo (USP)} and
{Harvard University} and {Pacific Northwest National Laboratory}
and {University Space Research Association (USRA)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Harvard University}
and {Brookhaven National Laboratory} and {Pacific Northwest
National Laboratory} and {Brookhaven National Laboratory}",
title = "Aircraft observations of the chemical composition and aging of
aerosol in the Manaus urban plume during GoAmazon 2014/5",
journal = "Atmospheric Chemistry and Physics",
year = "2019",
volume = "18",
number = "14",
pages = "10773--10797",
month = "July",
abstract = "The Green Ocean Amazon (GoAmazon 2014/5) campaign, conducted from
January 2014 to December 2015 in the vicinity of Manaus, Brazil,
was designed to study the aerosol life cycle and aerosol-cloud
interactions in both pristine and anthropogenically influenced
conditions. As part of this campaign, the U.S. Department of
Energy (DOE) Gulf-stream 1 (G-1) research aircraft was deployed
from 17 February to 25 March 2014 (wet season) and 6 September to
5 October 2014 (dry season) to investigate aerosol and cloud
properties aloft. Here, we present results from the G-1
deployments focusing on measurements of the aerosol chemical
composition and secondary organic aerosol (SOA) formation and
aging. In the first portion of the paper, we provide an overview
of the data and compare and contrast the data from the wet and dry
season. Organic aerosol (OA) dominates the deployment-averaged
chemical composition, comprising 80% of the non-refractory PM1
aerosol mass, with sulfate comprising 14 %, nitrate 2 %, and
ammonium 4 %. This product distribution was unchanged between
seasons, despite the fact that total aerosol loading was
significantly higher in the dry season and that regional and local
biomass burning was a significant source of OA mass in the dry,
but not wet, season. However, the OA was more oxidized in the dry
season, with the median of the mean carbon oxidation state
increasing from -0.45 in the wet season to -0.02 in the dry
season. In the second portion of the paper, we discuss the
evolution of the Manaus plume, focusing on 13 March 2014, one of
the exemplary days in the wet season. On this flight, we observe a
clear increase in OA concentrations in the Manaus plume relative
to the background. As the plume is transported downwind and ages,
we observe dynamic changes in the OA. The mean carbon oxidation
state of the OA increases from -0.6 to -0.45 during the 4-5 h of
photochemical aging. Hydrocarbon-like organic aerosol (HOA) mass
is lost, with Delta HOA/Delta CO values decreasing from 17.6 mu g
m(-3) ppmv(-1) over Manaus to 10.6 mu g m(-3) ppmv(-1) 95 km
downwind. Loss of HOA is balanced out by formation of oxygenated
organic aerosol (OOA), with Delta OOA/Delta CO increasing from 9.2
to 23.1 mu g m(-3) ppmv(-1). Because hydrocarbon-like organic
aerosol (HOA) loss is balanced by OOA formation, we observe little
change in the net Delta org/Delta CO values; Delta org/Delta CO
averages 31 mu g m(3) ppmv(-1) and does not increase with aging.
Analysis of the Manaus plume evolution using data from two
additional flights in the wet season showed similar trends in
Delta org/Delta CO to the 13 March flight; Delta org/Delta CO
values averaged 34 mu g m(3) ppmv(-1) and showed little change
over 4-6.5 h of aging. Our observation of constant Delta org/Delta
CO are in contrast to literature studies of the outflow of several
North American cities, which report significant increases in Delta
org/Delta CO for the first day of plume aging. These observations
suggest that SOA formation in the Manaus plume occurs, at least in
part, by a different mechanism than observed in urban outflow
plumes in most other literature studies. Constant Delta org/Delta
CO with plume aging has been observed in many biomass burning
plumes, but we are unaware of reports of fresh urban emissions
aging in this manner. These observations show that urban pollution
emitted from Manaus in the wet season forms less particulate
downwind as it ages than urban pollution emitted from North
American cities.",
doi = "10.5194/acp-18-10773-2018",
url = "http://dx.doi.org/10.5194/acp-18-10773-2018",
issn = "1680-7316 and 1680-7324",
label = "self-archiving-INPE-MCTIC-GOV-BR",
language = "en",
targetfile = "acp-18-10773-2018.pdf",
urlaccessdate = "27 abr. 2024"
}