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Stormier Southern Hemisphere induced by topography and ocean circulation

A defining feature of Earth’s present-day climate is that the Southern Hemisphere is stormier than the Northern Hemisphere. Consistently, the Southern Hemisphere has a stronger jet stream and more extreme weather events than the Northern Hemisphere. Understanding the relative importance of land–ocea...

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Autores principales: Shaw, Tiffany A., Miyawaki, Osamu, Donohoe, Aaron
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9897485/
https://www.ncbi.nlm.nih.gov/pubmed/36469772
http://dx.doi.org/10.1073/pnas.2123512119
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author Shaw, Tiffany A.
Miyawaki, Osamu
Donohoe, Aaron
author_facet Shaw, Tiffany A.
Miyawaki, Osamu
Donohoe, Aaron
author_sort Shaw, Tiffany A.
collection PubMed
description A defining feature of Earth’s present-day climate is that the Southern Hemisphere is stormier than the Northern Hemisphere. Consistently, the Southern Hemisphere has a stronger jet stream and more extreme weather events than the Northern Hemisphere. Understanding the relative importance of land–ocean contrast, including topography, radiative processes, and ocean circulation for determining this storminess asymmetry is important and may be helpful for interpreting projections of future storminess. Here, we show that the stormier Southern Hemisphere is induced by nearly equal contributions from topography and the ocean circulation, which moves energy from the Southern to Northern Hemisphere. These findings are based on 1) diagnostic energetic analyses applied to observations and climate model simulations and 2) modifying surface (land and ocean) boundary conditions in climate model simulations. Flattening topography and prescribing hemispherically symmetric surface energy fluxes (the manifestation of ocean energy transport on the atmosphere) in a climate model reduce the storminess asymmetry from 23 to 12% and 11%, respectively. Finally, we use the energetic perspective to interpret storminess trends since the beginning of the satellite era. We show that the Southern Hemisphere has become stormier, consistent with implied ocean energy transport changes in the Southern Ocean. In the Northern Hemisphere, storminess has not changed significantly consistent with oceanic and radiative (increased absorption of sunlight due to the loss of sea ice and snow) changes opposing one another. The trends are qualitatively consistent with climate model projections.
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spelling pubmed-98974852023-02-04 Stormier Southern Hemisphere induced by topography and ocean circulation Shaw, Tiffany A. Miyawaki, Osamu Donohoe, Aaron Proc Natl Acad Sci U S A Physical Sciences A defining feature of Earth’s present-day climate is that the Southern Hemisphere is stormier than the Northern Hemisphere. Consistently, the Southern Hemisphere has a stronger jet stream and more extreme weather events than the Northern Hemisphere. Understanding the relative importance of land–ocean contrast, including topography, radiative processes, and ocean circulation for determining this storminess asymmetry is important and may be helpful for interpreting projections of future storminess. Here, we show that the stormier Southern Hemisphere is induced by nearly equal contributions from topography and the ocean circulation, which moves energy from the Southern to Northern Hemisphere. These findings are based on 1) diagnostic energetic analyses applied to observations and climate model simulations and 2) modifying surface (land and ocean) boundary conditions in climate model simulations. Flattening topography and prescribing hemispherically symmetric surface energy fluxes (the manifestation of ocean energy transport on the atmosphere) in a climate model reduce the storminess asymmetry from 23 to 12% and 11%, respectively. Finally, we use the energetic perspective to interpret storminess trends since the beginning of the satellite era. We show that the Southern Hemisphere has become stormier, consistent with implied ocean energy transport changes in the Southern Ocean. In the Northern Hemisphere, storminess has not changed significantly consistent with oceanic and radiative (increased absorption of sunlight due to the loss of sea ice and snow) changes opposing one another. The trends are qualitatively consistent with climate model projections. National Academy of Sciences 2022-12-05 2022-12-13 /pmc/articles/PMC9897485/ /pubmed/36469772 http://dx.doi.org/10.1073/pnas.2123512119 Text en Copyright © 2022 the Author(s). Published by PNAS.2022 https://creativecommons.org/licenses/by-nc-nd/4.0/This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Physical Sciences
Shaw, Tiffany A.
Miyawaki, Osamu
Donohoe, Aaron
Stormier Southern Hemisphere induced by topography and ocean circulation
title Stormier Southern Hemisphere induced by topography and ocean circulation
title_full Stormier Southern Hemisphere induced by topography and ocean circulation
title_fullStr Stormier Southern Hemisphere induced by topography and ocean circulation
title_full_unstemmed Stormier Southern Hemisphere induced by topography and ocean circulation
title_short Stormier Southern Hemisphere induced by topography and ocean circulation
title_sort stormier southern hemisphere induced by topography and ocean circulation
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9897485/
https://www.ncbi.nlm.nih.gov/pubmed/36469772
http://dx.doi.org/10.1073/pnas.2123512119
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