Impacts of multi-layer overlap on contrail radiative forcing
Condensation trails (“contrails”) which form behind aircraft are estimated to cause on the order of 50 % of the total climate forcing of aviation, matching the total impact of all accumulated aviation-attributable CO 2 . The climate impacts of these contrails are highly uncertain, in part due to the...
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ftdoajarticles:oai:doaj.org/article:b41ed4eb048a4515b46c982a2cb682b9 2023-05-15T17:35:53+02:00 Impacts of multi-layer overlap on contrail radiative forcing I. Sanz-Morère S. D. Eastham F. Allroggen R. L. Speth S. R. H. Barrett 2021-02-01T00:00:00Z https://doi.org/10.5194/acp-21-1649-2021 https://doaj.org/article/b41ed4eb048a4515b46c982a2cb682b9 EN eng Copernicus Publications https://acp.copernicus.org/articles/21/1649/2021/acp-21-1649-2021.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-21-1649-2021 1680-7316 1680-7324 https://doaj.org/article/b41ed4eb048a4515b46c982a2cb682b9 Atmospheric Chemistry and Physics, Vol 21, Pp 1649-1681 (2021) Physics QC1-999 Chemistry QD1-999 article 2021 ftdoajarticles https://doi.org/10.5194/acp-21-1649-2021 2022-12-31T06:56:11Z Condensation trails (“contrails”) which form behind aircraft are estimated to cause on the order of 50 % of the total climate forcing of aviation, matching the total impact of all accumulated aviation-attributable CO 2 . The climate impacts of these contrails are highly uncertain, in part due to the effect of overlap between contrails and other cloud layers. Although literature estimates suggest that overlap could change even the sign of contrail radiative forcing (RF), the impacts of cloud–contrail overlaps are not well understood, and the effect of contrail–contrail overlap has never been quantified. In this study we develop and apply a new model of contrail radiative forcing which explicitly accounts for overlap between cloud layers. Assuming maximum possible overlap to provide an upper bound on impacts, cloud–contrail overlap is found to reduce the shortwave-cooling effect attributable to aviation by 66 % while reducing the longwave-warming effect by only 37 %. Therefore, on average in 2015, cloud–contrail overlap increased the net radiative forcing from contrails. We also quantify the sensitivity of contrail radiative forcing to cloud cover with respect to geographic location. Clouds significantly increase warming at high latitudes and over sea, transforming cooling contrails into warming ones in the North Atlantic corridor. Based on the same data, our results indicate that disregarding overlap between a given pair of contrail layers can result in longwave and shortwave radiative forcing being overestimated by up to 16 % and 25 %, respectively, with the highest bias observed at high optical depths ( > 0.4) and high solar zenith angles ( > 75 ∘ ). When applied to estimated global contrail coverage data for 2015, contrail–contrail overlap reduces both the longwave and shortwave forcing by ∼ 2 % relative to calculations which ignore overlap. The effect is greater for longwave radiation, resulting in a 3 % net reduction in the estimated RF when overlap is correctly accounted for. This suggests that ... Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Atmospheric Chemistry and Physics 21 3 1649 1681 |
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Physics QC1-999 Chemistry QD1-999 |
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Physics QC1-999 Chemistry QD1-999 I. Sanz-Morère S. D. Eastham F. Allroggen R. L. Speth S. R. H. Barrett Impacts of multi-layer overlap on contrail radiative forcing |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
Condensation trails (“contrails”) which form behind aircraft are estimated to cause on the order of 50 % of the total climate forcing of aviation, matching the total impact of all accumulated aviation-attributable CO 2 . The climate impacts of these contrails are highly uncertain, in part due to the effect of overlap between contrails and other cloud layers. Although literature estimates suggest that overlap could change even the sign of contrail radiative forcing (RF), the impacts of cloud–contrail overlaps are not well understood, and the effect of contrail–contrail overlap has never been quantified. In this study we develop and apply a new model of contrail radiative forcing which explicitly accounts for overlap between cloud layers. Assuming maximum possible overlap to provide an upper bound on impacts, cloud–contrail overlap is found to reduce the shortwave-cooling effect attributable to aviation by 66 % while reducing the longwave-warming effect by only 37 %. Therefore, on average in 2015, cloud–contrail overlap increased the net radiative forcing from contrails. We also quantify the sensitivity of contrail radiative forcing to cloud cover with respect to geographic location. Clouds significantly increase warming at high latitudes and over sea, transforming cooling contrails into warming ones in the North Atlantic corridor. Based on the same data, our results indicate that disregarding overlap between a given pair of contrail layers can result in longwave and shortwave radiative forcing being overestimated by up to 16 % and 25 %, respectively, with the highest bias observed at high optical depths ( > 0.4) and high solar zenith angles ( > 75 ∘ ). When applied to estimated global contrail coverage data for 2015, contrail–contrail overlap reduces both the longwave and shortwave forcing by ∼ 2 % relative to calculations which ignore overlap. The effect is greater for longwave radiation, resulting in a 3 % net reduction in the estimated RF when overlap is correctly accounted for. This suggests that ... |
format |
Article in Journal/Newspaper |
author |
I. Sanz-Morère S. D. Eastham F. Allroggen R. L. Speth S. R. H. Barrett |
author_facet |
I. Sanz-Morère S. D. Eastham F. Allroggen R. L. Speth S. R. H. Barrett |
author_sort |
I. Sanz-Morère |
title |
Impacts of multi-layer overlap on contrail radiative forcing |
title_short |
Impacts of multi-layer overlap on contrail radiative forcing |
title_full |
Impacts of multi-layer overlap on contrail radiative forcing |
title_fullStr |
Impacts of multi-layer overlap on contrail radiative forcing |
title_full_unstemmed |
Impacts of multi-layer overlap on contrail radiative forcing |
title_sort |
impacts of multi-layer overlap on contrail radiative forcing |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/acp-21-1649-2021 https://doaj.org/article/b41ed4eb048a4515b46c982a2cb682b9 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Atmospheric Chemistry and Physics, Vol 21, Pp 1649-1681 (2021) |
op_relation |
https://acp.copernicus.org/articles/21/1649/2021/acp-21-1649-2021.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-21-1649-2021 1680-7316 1680-7324 https://doaj.org/article/b41ed4eb048a4515b46c982a2cb682b9 |
op_doi |
https://doi.org/10.5194/acp-21-1649-2021 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
21 |
container_issue |
3 |
container_start_page |
1649 |
op_container_end_page |
1681 |
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