Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia
Biomass burning is a significant source of aerosol emissions in some regions and has a considerable impact on regional climate. Earth system model simulations indicate that increased biomass burning aerosol emissions contributed to statistically significant decreases in tropical precipitation over t...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/acf7d4 |
| _version_ | 1797672948168916992 |
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| author | Shay Magahey Gabriel J Kooperman |
| author_facet | Shay Magahey Gabriel J Kooperman |
| author_sort | Shay Magahey |
| collection | DOAJ |
| description | Biomass burning is a significant source of aerosol emissions in some regions and has a considerable impact on regional climate. Earth system model simulations indicate that increased biomass burning aerosol emissions contributed to statistically significant decreases in tropical precipitation over the 20th century. In this study, we use the Community Earth System Model version 1 Large Ensemble (CESM1-LENS) experiment to evaluate the mechanisms by which biomass burning aerosol contributed to decreased tropical precipitation, with a focus on South America and Southeast Asia. We analyze the all-but-one forcing simulations in which biomass burning aerosol emissions are held constant while other forcings (e.g., greenhouse gas concentrations) vary throughout the 20th century. This allows us to isolate the influence of biomass burning aerosol on processes that contribute to decreasing precipitation, including cloud microphysics, the radiative effects of absorbing aerosol particles, and alterations in regional circulation. We also show that the 20th century reduction in precipitation identified in the CESM1-LENS historical and biomass burning experiments is consistent across Coupled Model Intercomparison Project Phase 5 models with interactive aerosol schemes and the CESM2 single-forcing experiment. Our results demonstrate that higher concentrations of biomass burning aerosol increases the quantity of cloud condensation nuclei and cloud droplets, limiting cloud droplet size and precipitation formation. Additionally, absorbing aerosols (e.g., black carbon) contribute to a warmer cloud layer, which promotes cloud evaporation, increases atmospheric stability, and alters regional circulation patterns. Corresponding convectively coupled circulation responses, particularly over the tropical Andes, contribute to further reducing the flow of moisture and moisture convergence over tropical land. These results elucidate the processes that affect the water cycle in regions prone to biomass burning and inform our understanding of how future changes in aerosol emissions may impact tropical precipitation over the 21st century. |
| first_indexed | 2024-03-11T21:38:30Z |
| format | Article |
| id | doaj.art-2967f0c932e146b4a56eaa3e4feb2e3f |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-11T21:38:30Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-2967f0c932e146b4a56eaa3e4feb2e3f2023-09-26T14:56:04ZengIOP PublishingEnvironmental Research Letters1748-93262023-01-01181010402910.1088/1748-9326/acf7d4Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast AsiaShay Magahey0https://orcid.org/0000-0003-1204-3895Gabriel J Kooperman1https://orcid.org/0000-0002-3174-4913Department of Geography, University of Georgia , Athens, GA, United States of AmericaDepartment of Geography, University of Georgia , Athens, GA, United States of AmericaBiomass burning is a significant source of aerosol emissions in some regions and has a considerable impact on regional climate. Earth system model simulations indicate that increased biomass burning aerosol emissions contributed to statistically significant decreases in tropical precipitation over the 20th century. In this study, we use the Community Earth System Model version 1 Large Ensemble (CESM1-LENS) experiment to evaluate the mechanisms by which biomass burning aerosol contributed to decreased tropical precipitation, with a focus on South America and Southeast Asia. We analyze the all-but-one forcing simulations in which biomass burning aerosol emissions are held constant while other forcings (e.g., greenhouse gas concentrations) vary throughout the 20th century. This allows us to isolate the influence of biomass burning aerosol on processes that contribute to decreasing precipitation, including cloud microphysics, the radiative effects of absorbing aerosol particles, and alterations in regional circulation. We also show that the 20th century reduction in precipitation identified in the CESM1-LENS historical and biomass burning experiments is consistent across Coupled Model Intercomparison Project Phase 5 models with interactive aerosol schemes and the CESM2 single-forcing experiment. Our results demonstrate that higher concentrations of biomass burning aerosol increases the quantity of cloud condensation nuclei and cloud droplets, limiting cloud droplet size and precipitation formation. Additionally, absorbing aerosols (e.g., black carbon) contribute to a warmer cloud layer, which promotes cloud evaporation, increases atmospheric stability, and alters regional circulation patterns. Corresponding convectively coupled circulation responses, particularly over the tropical Andes, contribute to further reducing the flow of moisture and moisture convergence over tropical land. These results elucidate the processes that affect the water cycle in regions prone to biomass burning and inform our understanding of how future changes in aerosol emissions may impact tropical precipitation over the 21st century.https://doi.org/10.1088/1748-9326/acf7d4biomass burning aerosolprecipitationEarth System ModelingCommunity Earth System Modellarge ensemble experiment |
| spellingShingle | Shay Magahey Gabriel J Kooperman Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia Environmental Research Letters biomass burning aerosol precipitation Earth System Modeling Community Earth System Model large ensemble experiment |
| title | Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia |
| title_full | Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia |
| title_fullStr | Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia |
| title_full_unstemmed | Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia |
| title_short | Isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in South America and Southeast Asia |
| title_sort | isolating the effect of biomass burning aerosol emissions on 20th century hydroclimate in south america and southeast asia |
| topic | biomass burning aerosol precipitation Earth System Modeling Community Earth System Model large ensemble experiment |
| url | https://doi.org/10.1088/1748-9326/acf7d4 |
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