Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific

<p>Cumulus clouds are common over maritime regions. They are important regulators of the global radiative energy budget and global hydrologic cycle, as well as a key contributor to the uncertainty in anthropogenic climate change projections due to uncertainty in aerosol–cloud interactions. The...

Full description

Bibliographic Details
Main Authors: R. M. Miller, R. M. Rauber, L. Di Girolamo, M. Rilloraza, D. Fu, G. M. McFarquhar, S. W. Nesbitt, L. D. Ziemba, S. Woods, K. L. Thornhill
Format: Article
Language:English
Published: Copernicus Publications 2023-08-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/23/8959/2023/acp-23-8959-2023.pdf
_version_ 1797745065281454080
author R. M. Miller
R. M. Rauber
L. Di Girolamo
M. Rilloraza
D. Fu
D. Fu
G. M. McFarquhar
G. M. McFarquhar
S. W. Nesbitt
L. D. Ziemba
S. Woods
K. L. Thornhill
K. L. Thornhill
author_facet R. M. Miller
R. M. Rauber
L. Di Girolamo
M. Rilloraza
D. Fu
D. Fu
G. M. McFarquhar
G. M. McFarquhar
S. W. Nesbitt
L. D. Ziemba
S. Woods
K. L. Thornhill
K. L. Thornhill
author_sort R. M. Miller
collection DOAJ
description <p>Cumulus clouds are common over maritime regions. They are important regulators of the global radiative energy budget and global hydrologic cycle, as well as a key contributor to the uncertainty in anthropogenic climate change projections due to uncertainty in aerosol–cloud interactions. These interactions are regionally specific owing to their strong influences on aerosol sources and meteorology. Here, our analysis focuses on the statistical properties of marine boundary layer (MBL) aerosol chemistry and the relationships of MBL aerosol to cumulus cloud properties just above cloud base as sampled in 2019 during the NASA Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP<span class="inline-formula"><sup>2</sup></span>Ex). The aerosol and clouds were sampled by instruments on the NASA P-3 aircraft over three distinct maritime regions around the Philippines: the West Pacific, the South China Sea, and the Sulu Sea.</p> <p>Our analysis shows three primary sources influenced the aerosol chemical composition: clean marine (ocean source), industrial (Southeast Asia, Manila, and cargo and tanker ship emissions), and biomass burning (Borneo and Indonesia). The clean marine aerosol chemical composition had low values of all sampled chemical signatures, specifically median values of 2.2 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of organics (ORG), 2.3 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">SO<sub>4</sub></span>, 0.3 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">NO<sub>3</sub></span>, 1.4 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">NH<sub>4</sub></span>, 0.04 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of Cl, and 0.0074 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of refractory black carbon (BC). Chemical signatures of the other two aerosol source regions were industrial, with elevated <span class="inline-formula">SO<sub>4</sub></span> having a median value of 6.1 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span>, and biomass burning, with elevated median concentrations of ORG 21.2 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> and BC 0.1351 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span>. Based on chemical signatures, the industrial component was primarily from ship emissions, which were sampled within 60 km of ships and within projected ship plumes. Normalized cloud droplet size distributions in clouds sampled near the MBL passes of the P-3 showed that clouds impacted by industrial and biomass burning contained higher concentrations of cloud droplets, by as much as 1.5 orders of magnitude for diameters <span class="inline-formula">&lt;</span> 13 <span class="inline-formula">µm</span> compared to clean marine clouds, while at size ranges between 13.0–34.5 <span class="inline-formula">µm</span> the median concentrations of cloud droplets in all aerosol categories were nearly an order of magnitude less than the clean marine category. In the droplet size bins centered at diameters <span class="inline-formula">&gt;</span> 34.5 <span class="inline-formula">µm</span> concentrations were equal to, or slightly exceeded, the concentrations of the clean marine clouds. These analyses show that anthropogenic aerosols generated from industrial and biomass<span id="page8960"/> burning sources significantly influenced cloud base microphysical structure in the Philippine region enhancing the small droplet concentration and reducing the concentration of mid-sized droplets.</p>
first_indexed 2024-03-12T15:18:10Z
format Article
id doaj.art-9e333236f6a548fabd35c12a0cb7873b
institution Directory Open Access Journal
issn 1680-7316
1680-7324
language English
last_indexed 2024-03-12T15:18:10Z
publishDate 2023-08-01
publisher Copernicus Publications
record_format Article
series Atmospheric Chemistry and Physics
spelling doaj.art-9e333236f6a548fabd35c12a0cb7873b2023-08-11T09:06:15ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-08-01238959897710.5194/acp-23-8959-2023Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West PacificR. M. Miller0R. M. Rauber1L. Di Girolamo2M. Rilloraza3D. Fu4D. Fu5G. M. McFarquhar6G. M. McFarquhar7S. W. Nesbitt8L. D. Ziemba9S. Woods10K. L. Thornhill11K. L. Thornhill12Department of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USADepartment of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USADepartment of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USADepartment of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USADepartment of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USASpace Science and Engineering Center, University of Wisconsin–Madison, Madison, WI, USACooperative Institute for Severe and High Impact Weather Research and Operations, University of Oklahoma, Norman, OK, USASchool of Meteorology, University of Oklahoma, Norman, OK, USADepartment of Atmospheric Science, University of Illinois Urbana–Champaign, Urbana, IL, USANASA Langley Research Center, Hampton, VA, USANational Center for Atmospheric Research, Boulder, CO, USANASA Langley Research Center, Hampton, VA, USAScience Systems and Applications, Inc., Hampton, VA, USA<p>Cumulus clouds are common over maritime regions. They are important regulators of the global radiative energy budget and global hydrologic cycle, as well as a key contributor to the uncertainty in anthropogenic climate change projections due to uncertainty in aerosol–cloud interactions. These interactions are regionally specific owing to their strong influences on aerosol sources and meteorology. Here, our analysis focuses on the statistical properties of marine boundary layer (MBL) aerosol chemistry and the relationships of MBL aerosol to cumulus cloud properties just above cloud base as sampled in 2019 during the NASA Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP<span class="inline-formula"><sup>2</sup></span>Ex). The aerosol and clouds were sampled by instruments on the NASA P-3 aircraft over three distinct maritime regions around the Philippines: the West Pacific, the South China Sea, and the Sulu Sea.</p> <p>Our analysis shows three primary sources influenced the aerosol chemical composition: clean marine (ocean source), industrial (Southeast Asia, Manila, and cargo and tanker ship emissions), and biomass burning (Borneo and Indonesia). The clean marine aerosol chemical composition had low values of all sampled chemical signatures, specifically median values of 2.2 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of organics (ORG), 2.3 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">SO<sub>4</sub></span>, 0.3 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">NO<sub>3</sub></span>, 1.4 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of <span class="inline-formula">NH<sub>4</sub></span>, 0.04 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of Cl, and 0.0074 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> of refractory black carbon (BC). Chemical signatures of the other two aerosol source regions were industrial, with elevated <span class="inline-formula">SO<sub>4</sub></span> having a median value of 6.1 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span>, and biomass burning, with elevated median concentrations of ORG 21.2 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span> and BC 0.1351 <span class="inline-formula">µg</span> m<span class="inline-formula"><sup>−3</sup></span>. Based on chemical signatures, the industrial component was primarily from ship emissions, which were sampled within 60 km of ships and within projected ship plumes. Normalized cloud droplet size distributions in clouds sampled near the MBL passes of the P-3 showed that clouds impacted by industrial and biomass burning contained higher concentrations of cloud droplets, by as much as 1.5 orders of magnitude for diameters <span class="inline-formula">&lt;</span> 13 <span class="inline-formula">µm</span> compared to clean marine clouds, while at size ranges between 13.0–34.5 <span class="inline-formula">µm</span> the median concentrations of cloud droplets in all aerosol categories were nearly an order of magnitude less than the clean marine category. In the droplet size bins centered at diameters <span class="inline-formula">&gt;</span> 34.5 <span class="inline-formula">µm</span> concentrations were equal to, or slightly exceeded, the concentrations of the clean marine clouds. These analyses show that anthropogenic aerosols generated from industrial and biomass<span id="page8960"/> burning sources significantly influenced cloud base microphysical structure in the Philippine region enhancing the small droplet concentration and reducing the concentration of mid-sized droplets.</p>https://acp.copernicus.org/articles/23/8959/2023/acp-23-8959-2023.pdf
spellingShingle R. M. Miller
R. M. Rauber
L. Di Girolamo
M. Rilloraza
D. Fu
D. Fu
G. M. McFarquhar
G. M. McFarquhar
S. W. Nesbitt
L. D. Ziemba
S. Woods
K. L. Thornhill
K. L. Thornhill
Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
Atmospheric Chemistry and Physics
title Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
title_full Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
title_fullStr Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
title_full_unstemmed Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
title_short Influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the South China Sea and West Pacific
title_sort influence of natural and anthropogenic aerosols on cloud base droplet size distributions in clouds over the south china sea and west pacific
url https://acp.copernicus.org/articles/23/8959/2023/acp-23-8959-2023.pdf
work_keys_str_mv AT rmmiller influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT rmrauber influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT ldigirolamo influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT mrilloraza influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT dfu influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT dfu influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT gmmcfarquhar influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT gmmcfarquhar influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT swnesbitt influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT ldziemba influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT swoods influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT klthornhill influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific
AT klthornhill influenceofnaturalandanthropogenicaerosolsoncloudbasedropletsizedistributionsincloudsoverthesouthchinaseaandwestpacific