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Title: Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

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 analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed 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 aremore » 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 collision–coalescence 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 collision–coalescence process. This paper shows that the pollution produced by Manaus significantly affects warm-phase 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 endeavors.« less

Authors:
 [1];  [1];  [2];  [2];  [2];  [2];  [2];  [2];  [3];  [4];  [3]
  1. National Institute for Space Research (INPE) (Brazil). Center for Weather Forecasting and Climate Research (CPTEC)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Univ. de Sao Paulo (USP), Sao Paulo (Brazil)
  4. Harvard Univ., Cambridge, MA (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1324273
Report Number(s):
BNL-112537-2016-JA
Journal ID: ISSN 1680-7324; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:  
SC00112704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Volume: 16; Journal Issue: 11; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Cecchini, Micael A., Machado, Luiz A. T., Comstock, Jennifer M., Mei, Fan, Wang, Jian, Fan, Jiwen, Tomlinson, Jason M., Schmid, Beat, Albrecht, Rachel, Martin, Scot T., and Artaxo, Paulo. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season. United States: N. p., 2016. Web. doi:10.5194/acp-16-7029-2016.
Cecchini, Micael A., Machado, Luiz A. T., Comstock, Jennifer M., Mei, Fan, Wang, Jian, Fan, Jiwen, Tomlinson, Jason M., Schmid, Beat, Albrecht, Rachel, Martin, Scot T., & Artaxo, Paulo. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season. United States. https://doi.org/10.5194/acp-16-7029-2016
Cecchini, Micael A., Machado, Luiz A. T., Comstock, Jennifer M., Mei, Fan, Wang, Jian, Fan, Jiwen, Tomlinson, Jason M., Schmid, Beat, Albrecht, Rachel, Martin, Scot T., and Artaxo, Paulo. 2016. "Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season". United States. https://doi.org/10.5194/acp-16-7029-2016. https://www.osti.gov/servlets/purl/1324273.
@article{osti_1324273,
title = {Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season},
author = {Cecchini, Micael A. and Machado, Luiz A. T. 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},
abstractNote = {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 analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed 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 collision–coalescence 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 collision–coalescence process. This paper shows that the pollution produced by Manaus significantly affects warm-phase 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 endeavors.},
doi = {10.5194/acp-16-7029-2016},
url = {https://www.osti.gov/biblio/1324273}, journal = {Atmospheric Chemistry and Physics (Online)},
issn = {1680-7324},
number = 11,
volume = 16,
place = {United States},
year = {Thu Jun 09 00:00:00 EDT 2016},
month = {Thu Jun 09 00:00:00 EDT 2016}
}

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Works referencing / citing this record:

Mesoscale convective systems over the Amazon basin: The GoAmazon2014/5 program
journal, June 2019


Substantial convection and precipitation enhancements by ultrafine aerosol particles
journal, January 2018


Sensitivities of Amazonian clouds to aerosols and updraft speed
journal, January 2017


Contributions of mobile, stationary and biogenic sources to air pollution in the Amazon rainforest: a numerical study with the WRF-Chem model
journal, January 2017


Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA
journal, January 2018


Quantifying the aerosol effect on droplet size distribution at cloud top
journal, January 2019


Aerosol properties and their influences on low warm clouds during the Two-Column Aerosol Project
journal, January 2019


The Green Ocean: precipitation insights from the GoAmazon2014/5 experiment
journal, January 2018


Aerosol Properties and Their Influences on Low Warm Clouds during the Two-Column Aerosol Project
posted_content, February 2019