On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change
Ridging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. W...
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ftsubggeo:oai:e-docs.geo-leo.de:11858/11164 2023-12-17T10:50:05+01:00 On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change Ivanciu, Ioana Ndarana, Thando Matthes, Katja Wahl, Sebastian 2 Department of Geography, Geoinformatics and Meteorology University of Pretoria Hartfield South Africa 1 GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel Germany 2022-10-19 https://doi.org/10.1029/2022GL099607 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11164 eng eng doi:10.1029/2022GL099607 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11164 This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. ddc:551.6 ridging highs Rossby wave breaking climate change climate modeling South African precipitation doc-type:article 2022 ftsubggeo https://doi.org/10.1029/2022GL099607 2023-11-19T23:12:31Z Ridging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. We show that the former type of RHs are associated with more precipitation than the latter type. The mean sea level pressure anomalies caused by the two types of RHs are characterized by distinct patterns, leading to differences in the flow of moisture‐laden air onto land. We additionally find that RWB mediates the effect of climate change on RHs during the twenty‐first century. Consequently, RHs occurring without RWB exhibit little change, while those occurring with RWB contribute more precipitation over the southern and less precipitation over the northeastern South Africa in the future. Plain Language Summary: The high pressure system located above the South Atlantic Ocean occasionally extends eastward over South Africa, leading to winds that blow onshore and carry moisture from the warm waters of the Southwest Indian Ocean to the coast. These events, termed ridging highs (RHs), bring an important contribution to precipitation over the southern and eastern parts of South Africa. Their occurrence is related to the propagation and breaking of atmospheric waves at the boundary between the troposphere and the stratosphere. This study categorizes RHs based on the behavior of atmospheric waves above and shows that events that are accompanied by wave breaking result in more precipitation over South Africa. In addition, model simulations are used to investigate the impact of climate change during the twenty‐first century on RHs and the associated precipitation. Although the model predicts that in total South Africa will experience drier conditions in the future, RHs contribute to this drying trend only in the northeastern part of the country. In the southern part of South Africa, the model simulates that RHs will bring ... Article in Journal/Newspaper South Atlantic Ocean GEO-LEOe-docs (FID GEO) Indian Geophysical Research Letters 49 20 |
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Open Polar |
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GEO-LEOe-docs (FID GEO) |
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ftsubggeo |
language |
English |
topic |
ddc:551.6 ridging highs Rossby wave breaking climate change climate modeling South African precipitation |
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ddc:551.6 ridging highs Rossby wave breaking climate change climate modeling South African precipitation Ivanciu, Ioana Ndarana, Thando Matthes, Katja Wahl, Sebastian 2 Department of Geography, Geoinformatics and Meteorology University of Pretoria Hartfield South Africa 1 GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel Germany On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
topic_facet |
ddc:551.6 ridging highs Rossby wave breaking climate change climate modeling South African precipitation |
description |
Ridging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. We show that the former type of RHs are associated with more precipitation than the latter type. The mean sea level pressure anomalies caused by the two types of RHs are characterized by distinct patterns, leading to differences in the flow of moisture‐laden air onto land. We additionally find that RWB mediates the effect of climate change on RHs during the twenty‐first century. Consequently, RHs occurring without RWB exhibit little change, while those occurring with RWB contribute more precipitation over the southern and less precipitation over the northeastern South Africa in the future. Plain Language Summary: The high pressure system located above the South Atlantic Ocean occasionally extends eastward over South Africa, leading to winds that blow onshore and carry moisture from the warm waters of the Southwest Indian Ocean to the coast. These events, termed ridging highs (RHs), bring an important contribution to precipitation over the southern and eastern parts of South Africa. Their occurrence is related to the propagation and breaking of atmospheric waves at the boundary between the troposphere and the stratosphere. This study categorizes RHs based on the behavior of atmospheric waves above and shows that events that are accompanied by wave breaking result in more precipitation over South Africa. In addition, model simulations are used to investigate the impact of climate change during the twenty‐first century on RHs and the associated precipitation. Although the model predicts that in total South Africa will experience drier conditions in the future, RHs contribute to this drying trend only in the northeastern part of the country. In the southern part of South Africa, the model simulates that RHs will bring ... |
format |
Article in Journal/Newspaper |
author |
Ivanciu, Ioana Ndarana, Thando Matthes, Katja Wahl, Sebastian 2 Department of Geography, Geoinformatics and Meteorology University of Pretoria Hartfield South Africa 1 GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel Germany |
author_facet |
Ivanciu, Ioana Ndarana, Thando Matthes, Katja Wahl, Sebastian 2 Department of Geography, Geoinformatics and Meteorology University of Pretoria Hartfield South Africa 1 GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel Germany |
author_sort |
Ivanciu, Ioana |
title |
On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
title_short |
On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
title_full |
On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
title_fullStr |
On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
title_full_unstemmed |
On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change |
title_sort |
on the ridging of the south atlantic anticyclone over south africa: the impact of rossby wave breaking and of climate change |
publishDate |
2022 |
url |
https://doi.org/10.1029/2022GL099607 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11164 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
doi:10.1029/2022GL099607 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11164 |
op_rights |
This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. |
op_doi |
https://doi.org/10.1029/2022GL099607 |
container_title |
Geophysical Research Letters |
container_volume |
49 |
container_issue |
20 |
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1785574750074961920 |