How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments
Wildfires are a significant source of absorbing aerosols in the atmosphere. Extreme fires in particular, such as those during the 2019-2020 Australian wildfire season (Black Summer fires), can have considerable large-scale effects. In this context, the climate impact of extreme wildfires unfolds not...
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ftleibnizopen:oai:oai.leibnizopen.de:E7u2IJEBBwLIz6xGxxGu 2024-09-15T18:37:24+00:00 How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments Senf, Fabian Heinold, Bernd Kubin, Anne Müller, Jason Schrödner, Roland Tegen, Ina 2023 application/pdf https://oa.tib.eu/renate/handle/123456789/14690 https://doi.org/10.34657/13712 eng eng Katlenburg-Lindau : EGU CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0 550 Australia aerosol atmospheric circulation carbon dioxide climate effect climate modeling longwave radiation meridional circulation radiative forcing Southern Hemisphere stratosphere troposphere wildfire Article Text 2023 ftleibnizopen https://doi.org/10.34657/13712 2024-08-05T12:41:46Z Wildfires are a significant source of absorbing aerosols in the atmosphere. Extreme fires in particular, such as those during the 2019-2020 Australian wildfire season (Black Summer fires), can have considerable large-scale effects. In this context, the climate impact of extreme wildfires unfolds not only because of the emitted carbon dioxide but also due to smoke aerosol released up to an altitude of 17ĝ€¯km. The overall aerosol effects depend on a variety of factors, such as the amount emitted, the injection height, and the composition of the burned material, and is therefore subject to considerable uncertainty. In the present study, we address the global impact caused by the exceptionally strong and high-reaching smoke emissions from the Australian wildfires using simulations with a global aerosol-climate model. We show that the absorption of solar radiation by the black carbon contained in the emitted smoke led to a shortwave radiative forcing of more than +5ĝ€¯Wm-2 in the southern mid-latitudes of the lower stratosphere. Subsequent adjustment processes in the stratosphere slowed down the diabatically driven meridional circulation, thus redistributing the heating perturbation on a global scale. As a result of these stratospheric adjustments, a positive temperature perturbation developed in both hemispheres, leading to additional longwave radiation emitted back to space. According to the model results, this adjustment occurred in the stratosphere within the first 2 months after the event. At the top of the atmosphere (TOA), the net effective radiative forcing (ERF) averaged over the Southern Hemisphere was initially dominated by the instantaneous positive radiative forcing of about +0.5ĝ€¯Wm-2, for which the positive sign resulted mainly from the presence of clouds above the Southern Ocean. The longwave adjustments led to a compensation of the initially net positive TOA ERF, which is seen in the Southern Hemisphere, the tropics, and the northern mid-latitudes. The simulated changes in the lower stratosphere ... Article in Journal/Newspaper Southern Ocean LeibnizOpen (The Leibniz Association) |
institution |
Open Polar |
collection |
LeibnizOpen (The Leibniz Association) |
op_collection_id |
ftleibnizopen |
language |
English |
topic |
550 Australia aerosol atmospheric circulation carbon dioxide climate effect climate modeling longwave radiation meridional circulation radiative forcing Southern Hemisphere stratosphere troposphere wildfire |
spellingShingle |
550 Australia aerosol atmospheric circulation carbon dioxide climate effect climate modeling longwave radiation meridional circulation radiative forcing Southern Hemisphere stratosphere troposphere wildfire Senf, Fabian Heinold, Bernd Kubin, Anne Müller, Jason Schrödner, Roland Tegen, Ina How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
topic_facet |
550 Australia aerosol atmospheric circulation carbon dioxide climate effect climate modeling longwave radiation meridional circulation radiative forcing Southern Hemisphere stratosphere troposphere wildfire |
description |
Wildfires are a significant source of absorbing aerosols in the atmosphere. Extreme fires in particular, such as those during the 2019-2020 Australian wildfire season (Black Summer fires), can have considerable large-scale effects. In this context, the climate impact of extreme wildfires unfolds not only because of the emitted carbon dioxide but also due to smoke aerosol released up to an altitude of 17ĝ€¯km. The overall aerosol effects depend on a variety of factors, such as the amount emitted, the injection height, and the composition of the burned material, and is therefore subject to considerable uncertainty. In the present study, we address the global impact caused by the exceptionally strong and high-reaching smoke emissions from the Australian wildfires using simulations with a global aerosol-climate model. We show that the absorption of solar radiation by the black carbon contained in the emitted smoke led to a shortwave radiative forcing of more than +5ĝ€¯Wm-2 in the southern mid-latitudes of the lower stratosphere. Subsequent adjustment processes in the stratosphere slowed down the diabatically driven meridional circulation, thus redistributing the heating perturbation on a global scale. As a result of these stratospheric adjustments, a positive temperature perturbation developed in both hemispheres, leading to additional longwave radiation emitted back to space. According to the model results, this adjustment occurred in the stratosphere within the first 2 months after the event. At the top of the atmosphere (TOA), the net effective radiative forcing (ERF) averaged over the Southern Hemisphere was initially dominated by the instantaneous positive radiative forcing of about +0.5ĝ€¯Wm-2, for which the positive sign resulted mainly from the presence of clouds above the Southern Ocean. The longwave adjustments led to a compensation of the initially net positive TOA ERF, which is seen in the Southern Hemisphere, the tropics, and the northern mid-latitudes. The simulated changes in the lower stratosphere ... |
format |
Article in Journal/Newspaper |
author |
Senf, Fabian Heinold, Bernd Kubin, Anne Müller, Jason Schrödner, Roland Tegen, Ina |
author_facet |
Senf, Fabian Heinold, Bernd Kubin, Anne Müller, Jason Schrödner, Roland Tegen, Ina |
author_sort |
Senf, Fabian |
title |
How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
title_short |
How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
title_full |
How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
title_fullStr |
How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
title_full_unstemmed |
How the extreme 2019-2020 Australian wildfires affected global circulation and adjustments |
title_sort |
how the extreme 2019-2020 australian wildfires affected global circulation and adjustments |
publisher |
Katlenburg-Lindau : EGU |
publishDate |
2023 |
url |
https://oa.tib.eu/renate/handle/123456789/14690 https://doi.org/10.34657/13712 |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_rights |
CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0 |
op_doi |
https://doi.org/10.34657/13712 |
_version_ |
1810481770529816576 |