Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates

<p>Aerosol and cloud microphysical measurements were collected by a research aircraft during August 2019 over the United Arab Emirates (UAE). The majority of scientific flights targeted summertime convection along the eastern Al Hajar Mountains bordering Oman, while one flight sampled non-orog...

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Main Authors: Y. Wehbe, S. A. Tessendorf, C. Weeks, R. Bruintjes, L. Xue, R. Rasmussen, P. Lawson, S. Woods, M. Temimi
Format: Article
Language:English
Published: Copernicus Publications 2021-08-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/21/12543/2021/acp-21-12543-2021.pdf
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author Y. Wehbe
S. A. Tessendorf
C. Weeks
R. Bruintjes
L. Xue
R. Rasmussen
P. Lawson
S. Woods
M. Temimi
author_facet Y. Wehbe
S. A. Tessendorf
C. Weeks
R. Bruintjes
L. Xue
R. Rasmussen
P. Lawson
S. Woods
M. Temimi
author_sort Y. Wehbe
collection DOAJ
description <p>Aerosol and cloud microphysical measurements were collected by a research aircraft during August 2019 over the United Arab Emirates (UAE). The majority of scientific flights targeted summertime convection along the eastern Al Hajar Mountains bordering Oman, while one flight sampled non-orographic clouds over the western UAE near the Saudi Arabian border. In this work, we study the evolution of growing cloud turrets from cloud base (9 <span class="inline-formula"><sup>∘</sup></span>C) up to the capping inversion level (<span class="inline-formula">−12</span> <span class="inline-formula"><sup>∘</sup></span>C) using coincident cloud particle imagery and particle size distributions from cloud cores under different forcing. Results demonstrate the active role of background dust and pollution as cloud condensation nuclei (CCN) with the onset of their deliquescence in the subcloud region. Subcloud aerosol sizes are shown to extend from submicron to 100 <span class="inline-formula">µ</span>m sizes, with higher concentrations of ultra-giant CCN (<span class="inline-formula"><i>d</i>&gt;10</span> <span class="inline-formula">µ</span>m) from local sources closer to the Saudi border, compared with the eastern orographic region where smaller CCN are observed. Despite the presence of ultra-giant CCN from dust and pollution in both regions, an active collision–coalescence (C–C) process is not observed within the limited depths of warm cloud (<span class="inline-formula">&lt;1000</span> m). The state-of-the-art observations presented in this paper can be used to initialize modeling case studies to examine the influence of aerosols on cloud and precipitation processes in the region and to better understand the impacts of hygroscopic cloud seeding on these clouds.</p>
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spelling doaj.art-71fe82bc2c01464189116916912299d22022-12-21T17:44:36ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-08-0121125431256010.5194/acp-21-12543-2021Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab EmiratesY. Wehbe0S. A. Tessendorf1C. Weeks2R. Bruintjes3L. Xue4R. Rasmussen5P. Lawson6S. Woods7M. Temimi8National Center of Meteorology, Abu Dhabi 4815, United Arab EmiratesResearch Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USAResearch Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USAResearch Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USAResearch Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USAResearch Applications Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USAStratton Park Engineering Company, Boulder, CO 80301, USAStratton Park Engineering Company, Boulder, CO 80301, USADepartment of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA<p>Aerosol and cloud microphysical measurements were collected by a research aircraft during August 2019 over the United Arab Emirates (UAE). The majority of scientific flights targeted summertime convection along the eastern Al Hajar Mountains bordering Oman, while one flight sampled non-orographic clouds over the western UAE near the Saudi Arabian border. In this work, we study the evolution of growing cloud turrets from cloud base (9 <span class="inline-formula"><sup>∘</sup></span>C) up to the capping inversion level (<span class="inline-formula">−12</span> <span class="inline-formula"><sup>∘</sup></span>C) using coincident cloud particle imagery and particle size distributions from cloud cores under different forcing. Results demonstrate the active role of background dust and pollution as cloud condensation nuclei (CCN) with the onset of their deliquescence in the subcloud region. Subcloud aerosol sizes are shown to extend from submicron to 100 <span class="inline-formula">µ</span>m sizes, with higher concentrations of ultra-giant CCN (<span class="inline-formula"><i>d</i>&gt;10</span> <span class="inline-formula">µ</span>m) from local sources closer to the Saudi border, compared with the eastern orographic region where smaller CCN are observed. Despite the presence of ultra-giant CCN from dust and pollution in both regions, an active collision–coalescence (C–C) process is not observed within the limited depths of warm cloud (<span class="inline-formula">&lt;1000</span> m). The state-of-the-art observations presented in this paper can be used to initialize modeling case studies to examine the influence of aerosols on cloud and precipitation processes in the region and to better understand the impacts of hygroscopic cloud seeding on these clouds.</p>https://acp.copernicus.org/articles/21/12543/2021/acp-21-12543-2021.pdf
spellingShingle Y. Wehbe
S. A. Tessendorf
C. Weeks
R. Bruintjes
L. Xue
R. Rasmussen
P. Lawson
S. Woods
M. Temimi
Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
Atmospheric Chemistry and Physics
title Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
title_full Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
title_fullStr Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
title_full_unstemmed Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
title_short Analysis of aerosol–cloud interactions and their implications for precipitation formation using aircraft observations over the United Arab Emirates
title_sort analysis of aerosol cloud interactions and their implications for precipitation formation using aircraft observations over the united arab emirates
url https://acp.copernicus.org/articles/21/12543/2021/acp-21-12543-2021.pdf
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