Exploring the uncertainties in the aviation soot–cirrus effect

<p>A global aerosol–climate model, including a two-moment cloud microphysical scheme and a parametrization for aerosol-induced ice formation in cirrus clouds, is applied in order to quantify the impact of aviation soot on natural cirrus clouds. Several sensitivity experiments are performed to...

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Autores principales:	M. Righi, J. Hendricks, C. G. Beer
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Physics QC1-999 Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/6a9eb7ba3ed14e5682a14751bdf8dc28
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spelling	oai:doaj.org-article:6a9eb7ba3ed14e5682a14751bdf8dc282021-11-30T09:02:13ZExploring the uncertainties in the aviation soot–cirrus effect10.5194/acp-21-17267-20211680-73161680-7324https://doaj.org/article/6a9eb7ba3ed14e5682a14751bdf8dc282021-11-01T00:00:00Zhttps://acp.copernicus.org/articles/21/17267/2021/acp-21-17267-2021.pdfhttps://doaj.org/toc/1680-7316https://doaj.org/toc/1680-7324<p>A global aerosol–climate model, including a two-moment cloud microphysical scheme and a parametrization for aerosol-induced ice formation in cirrus clouds, is applied in order to quantify the impact of aviation soot on natural cirrus clouds. Several sensitivity experiments are performed to assess the uncertainties in this effect related to (i) the assumptions on the ice nucleation abilities of aviation soot, (ii) the representation of vertical updrafts in the model, and (iii) the use of reanalysis data to relax the model dynamics (the so-called nudging technique). Based on the results of the model simulations, a radiative forcing from the aviation soot–cirrus effect in the range of <span class="inline-formula">−35</span> to <span class="inline-formula">13</span> mW m<span class="inline-formula"><sup>−2</sup></span> is quantified, depending on the assumed critical saturation ratio for ice nucleation and active fraction of aviation soot but with a confidence level below 95 % in several cases. Simple idealized experiments with prescribed vertical velocities further show that the uncertainties on this aspect of the model dynamics are critical for the investigated effect and could potentially add a factor of about 2 of further uncertainty to the model estimates of the resulting radiative forcing. The use of the nudging technique to relax model dynamics is proved essential in order to identify a statistically significant signal from the model internal variability, while simulations performed in free-running mode and with prescribed sea-surface temperatures and sea-ice concentrations are shown to be unable to provide robust estimates of the investigated effect. A comparison with analogous model studies on the aviation soot–cirrus effect show a very large model diversity, with a conspicuous lack of consensus across the various estimates, which points to the need for more in-depth analyses on the roots of such discrepancies.</p>M. RighiJ. HendricksC. G. BeerCopernicus PublicationsarticlePhysicsQC1-999ChemistryQD1-999ENAtmospheric Chemistry and Physics, Vol 21, Pp 17267-17289 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999 Chemistry QD1-999
spellingShingle	Physics QC1-999 Chemistry QD1-999 M. Righi J. Hendricks C. G. Beer Exploring the uncertainties in the aviation soot–cirrus effect
description	<p>A global aerosol–climate model, including a two-moment cloud microphysical scheme and a parametrization for aerosol-induced ice formation in cirrus clouds, is applied in order to quantify the impact of aviation soot on natural cirrus clouds. Several sensitivity experiments are performed to assess the uncertainties in this effect related to (i) the assumptions on the ice nucleation abilities of aviation soot, (ii) the representation of vertical updrafts in the model, and (iii) the use of reanalysis data to relax the model dynamics (the so-called nudging technique). Based on the results of the model simulations, a radiative forcing from the aviation soot–cirrus effect in the range of <span class="inline-formula">−35</span> to <span class="inline-formula">13</span> mW m<span class="inline-formula"><sup>−2</sup></span> is quantified, depending on the assumed critical saturation ratio for ice nucleation and active fraction of aviation soot but with a confidence level below 95 % in several cases. Simple idealized experiments with prescribed vertical velocities further show that the uncertainties on this aspect of the model dynamics are critical for the investigated effect and could potentially add a factor of about 2 of further uncertainty to the model estimates of the resulting radiative forcing. The use of the nudging technique to relax model dynamics is proved essential in order to identify a statistically significant signal from the model internal variability, while simulations performed in free-running mode and with prescribed sea-surface temperatures and sea-ice concentrations are shown to be unable to provide robust estimates of the investigated effect. A comparison with analogous model studies on the aviation soot–cirrus effect show a very large model diversity, with a conspicuous lack of consensus across the various estimates, which points to the need for more in-depth analyses on the roots of such discrepancies.</p>
format	article
author	M. Righi J. Hendricks C. G. Beer
author_facet	M. Righi J. Hendricks C. G. Beer
author_sort	M. Righi
title	Exploring the uncertainties in the aviation soot–cirrus effect
title_short	Exploring the uncertainties in the aviation soot–cirrus effect
title_full	Exploring the uncertainties in the aviation soot–cirrus effect
title_fullStr	Exploring the uncertainties in the aviation soot–cirrus effect
title_full_unstemmed	Exploring the uncertainties in the aviation soot–cirrus effect
title_sort	exploring the uncertainties in the aviation soot–cirrus effect
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/6a9eb7ba3ed14e5682a14751bdf8dc28
work_keys_str_mv	AT mrighi exploringtheuncertaintiesintheaviationsootcirruseffect AT jhendricks exploringtheuncertaintiesintheaviationsootcirruseffect AT cgbeer exploringtheuncertaintiesintheaviationsootcirruseffect
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Exploring the uncertainties in the aviation soot–cirrus effect

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