Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model
The mineral dust cycle in pre-industrial (PI) and last glacial maximum (LGM) simulations with the CMIP5 model HadGEM2-A is evaluated. The modeled global dust cycle is enhanced at the LGM, with larger emissions in the Southern hemisphere, consistent with some previous studies. Two different dust upli...
Published in: | Journal of Geophysical Research: Atmospheres |
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ftuniveastangl:oai:ueaeprints.uea.ac.uk:54712 2023-05-15T13:45:56+02:00 Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model Hopcroft, Peter Valdes, Paul Woodward, Stephanie Joshi, Manoj 2015-08-27 application/pdf https://ueaeprints.uea.ac.uk/id/eprint/54712/ https://ueaeprints.uea.ac.uk/id/eprint/54712/1/Hopcroft_et_al_2015_Journal_of_Geophysical_Research_Atmospheres.pdf https://doi.org/10.1002/2015JD023742 en eng https://ueaeprints.uea.ac.uk/id/eprint/54712/1/Hopcroft_et_al_2015_Journal_of_Geophysical_Research_Atmospheres.pdf Hopcroft, Peter, Valdes, Paul, Woodward, Stephanie and Joshi, Manoj (2015) Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model. Journal of Geophysical Research: Atmospheres, 120 (6). 8186–8205. ISSN 2169-897X doi:10.1002/2015JD023742 Article PeerReviewed 2015 ftuniveastangl https://doi.org/10.1002/2015JD023742 2023-01-30T21:41:30Z The mineral dust cycle in pre-industrial (PI) and last glacial maximum (LGM) simulations with the CMIP5 model HadGEM2-A is evaluated. The modeled global dust cycle is enhanced at the LGM, with larger emissions in the Southern hemisphere, consistent with some previous studies. Two different dust uplift schemes within HadGEM2 both show a similar LGM/PI increase in total emissions (60% and 80%) and global loading (100% and 75%), but there is a factor of three difference in the top of the atmosphere net LGM-PI direct radiative forcing (-1.2Wm−2 and -0.4Wm−2, respectively). This forcing is dominated by the short-wave effects in both schemes. Recent reconstructions of dust deposition fluxes suggest that the LGM increase is overestimated in the Southern Atlantic and underestimated over east Antarctica. The LGM dust deposition reconstructions do not strongly discern between these two dust schemes because deposition is dominated by larger (2-6Îijm diameter) particles for which the two schemes show similar loading in both time periods. The model with larger radiative forcing shows a larger relative emissions increase of smaller particles. This is because of the size-dependent friction velocity emissions threshold and different size distribution of the soil source particles compared with the second scheme. Size-dependence of the threshold velocity is consistent with the theory of saltation, implying that the model with larger radiative forcing is more realistic. However, the large difference in radiative forcing between the two schemes highlights the size distribution at emission as a major uncertainty in predicting the climatic effects of dust cycle changes. Article in Journal/Newspaper Antarc* Antarctica East Antarctica University of East Anglia: UEA Digital Repository East Antarctica Journal of Geophysical Research: Atmospheres 120 16 8186 8205 |
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University of East Anglia: UEA Digital Repository |
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ftuniveastangl |
language |
English |
description |
The mineral dust cycle in pre-industrial (PI) and last glacial maximum (LGM) simulations with the CMIP5 model HadGEM2-A is evaluated. The modeled global dust cycle is enhanced at the LGM, with larger emissions in the Southern hemisphere, consistent with some previous studies. Two different dust uplift schemes within HadGEM2 both show a similar LGM/PI increase in total emissions (60% and 80%) and global loading (100% and 75%), but there is a factor of three difference in the top of the atmosphere net LGM-PI direct radiative forcing (-1.2Wm−2 and -0.4Wm−2, respectively). This forcing is dominated by the short-wave effects in both schemes. Recent reconstructions of dust deposition fluxes suggest that the LGM increase is overestimated in the Southern Atlantic and underestimated over east Antarctica. The LGM dust deposition reconstructions do not strongly discern between these two dust schemes because deposition is dominated by larger (2-6Îijm diameter) particles for which the two schemes show similar loading in both time periods. The model with larger radiative forcing shows a larger relative emissions increase of smaller particles. This is because of the size-dependent friction velocity emissions threshold and different size distribution of the soil source particles compared with the second scheme. Size-dependence of the threshold velocity is consistent with the theory of saltation, implying that the model with larger radiative forcing is more realistic. However, the large difference in radiative forcing between the two schemes highlights the size distribution at emission as a major uncertainty in predicting the climatic effects of dust cycle changes. |
format |
Article in Journal/Newspaper |
author |
Hopcroft, Peter Valdes, Paul Woodward, Stephanie Joshi, Manoj |
spellingShingle |
Hopcroft, Peter Valdes, Paul Woodward, Stephanie Joshi, Manoj Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
author_facet |
Hopcroft, Peter Valdes, Paul Woodward, Stephanie Joshi, Manoj |
author_sort |
Hopcroft, Peter |
title |
Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
title_short |
Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
title_full |
Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
title_fullStr |
Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
title_full_unstemmed |
Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model |
title_sort |
last glacial maximum radiative forcing from mineral dust aerosols in an earth system model |
publishDate |
2015 |
url |
https://ueaeprints.uea.ac.uk/id/eprint/54712/ https://ueaeprints.uea.ac.uk/id/eprint/54712/1/Hopcroft_et_al_2015_Journal_of_Geophysical_Research_Atmospheres.pdf https://doi.org/10.1002/2015JD023742 |
geographic |
East Antarctica |
geographic_facet |
East Antarctica |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_relation |
https://ueaeprints.uea.ac.uk/id/eprint/54712/1/Hopcroft_et_al_2015_Journal_of_Geophysical_Research_Atmospheres.pdf Hopcroft, Peter, Valdes, Paul, Woodward, Stephanie and Joshi, Manoj (2015) Last glacial maximum radiative forcing from mineral dust aerosols in an Earth System model. Journal of Geophysical Research: Atmospheres, 120 (6). 8186–8205. ISSN 2169-897X doi:10.1002/2015JD023742 |
op_doi |
https://doi.org/10.1002/2015JD023742 |
container_title |
Journal of Geophysical Research: Atmospheres |
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120 |
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16 |
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8186 |
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8205 |
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1766232890102775808 |