Anthropogenic Aerosols Modulated 20th-Century Sahel Rainfall Variability Via Their Impacts on North Atlantic Sea Surface Temperature

Shipeng Zhang; Philip Stier; Guy Dagan; Minghuai Wang

doi:10.1029/2021GL095629

Anthropogenic Aerosols Modulated 20th-Century Sahel Rainfall Variability Via Their Impacts on North Atlantic Sea Surface Temperature

Shipeng Zhang^*, Philip Stier, Guy Dagan, Minghuai Wang

^*Corresponding author for this work

Fredy & Nadine Herrmann Institute of Earth Sciences

Research output: Contribution to journal › Letter › peer-review

8 Scopus citations

Abstract

The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.

Original language	American English
Article number	e2021GL095629
Journal	Geophysical Research Letters
Volume	49
Issue number	1
DOIs	https://doi.org/10.1029/2021GL095629
State	Published - 16 Jan 2022

Bibliographical note

Funding Information:
S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC‐Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1 ) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station‐based precipitation observational data set. We acknowledge the input4MIPS project ( https://esgf-node.llnl.gov/projects/input4mips/ ) for making the emission data available.

Funding Information:
S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC-Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station-based precipitation observational data set. We acknowledge the input4MIPS project (https://esgf-node.llnl.gov/projects/input4mips/) for making the emission data available.

Publisher Copyright:
© 2021. The Authors.

Keywords

North Atlantic variability
Sahel rainfall
aerosol-cloud-interactions
aerosols

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1029/2021GL095629

Cite this

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title = "Anthropogenic Aerosols Modulated 20th-Century Sahel Rainfall Variability Via Their Impacts on North Atlantic Sea Surface Temperature",

abstract = "The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.",

keywords = "North Atlantic variability, Sahel rainfall, aerosol-cloud-interactions, aerosols",

author = "Shipeng Zhang and Philip Stier and Guy Dagan and Minghuai Wang",

note = "Funding Information: S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC‐Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1 ) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station‐based precipitation observational data set. We acknowledge the input4MIPS project ( https://esgf-node.llnl.gov/projects/input4mips/ ) for making the emission data available. Funding Information: S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC-Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station-based precipitation observational data set. We acknowledge the input4MIPS project (https://esgf-node.llnl.gov/projects/input4mips/) for making the emission data available. Publisher Copyright: {\textcopyright} 2021. The Authors.",

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AU - Dagan, Guy

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N1 - Funding Information: S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC‐Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1 ) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station‐based precipitation observational data set. We acknowledge the input4MIPS project ( https://esgf-node.llnl.gov/projects/input4mips/ ) for making the emission data available. Funding Information: S. Z., G. D., and P. S. are supported by the European Research Council (ERC) project constRaining the EffeCts of Aerosols on Precipitation (RECAP) under the European Union's Horizon 2020 research and innovation programme with Grant Agreement No. 724602. S. Z. is supported by the NERC-Oxford Doctorial training partnership in Environmental Research. M. W. is supported by the Natural Science Foundation of China (91744208, 41925023, 41575073, and 41621005), and the Ministry of Science and Technology of the People's Republic of China (2017YFA0604002 and 2016YFC0200503). G. D. was also supported by the Israeli Science Foundation Grant (1419/21). We acknowledge the CESM Large Ensemble Community Project. This material is based in part on work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation (NSF) under Cooperative Agreement 1852977. We also acknowledge the Canadian Centre for Climate Modeling for making the CanESM2 Large Ensemble simulations available. We acknowledge the WCRP's Working Group on Coupled Modeling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table S1 in Supporting Information S1) for producing and making available their model output. We thank the Hadley Centre and NOAA for making their SST data sets available. We also thank the data set from the Climate Research Unit for providing the station-based precipitation observational data set. We acknowledge the input4MIPS project (https://esgf-node.llnl.gov/projects/input4mips/) for making the emission data available. Publisher Copyright: © 2021. The Authors.

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N2 - The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.

AB - The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.

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Anthropogenic Aerosols Modulated 20th-Century Sahel Rainfall Variability Via Their Impacts on North Atlantic Sea Surface Temperature

Abstract

Bibliographical note

Keywords

UN SDGs

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