Circulation mechanisms responsible for wet or dry summers over Zimbabwe
Climate change has resulted in increased rainfall variability over many parts of the world including Southern Africa. As such, droughts and floods have become a frequent phenomenon in Zimbabwe and have potential to intensify socio-economic stressors. This study examined possible forcing factors behi...
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Online Access: | https://doi.org/10.3934/environsci.2018.3.154 https://doaj.org/article/3672646a54f64fac9f9745bf0e610157 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:3672646a54f64fac9f9745bf0e610157 2023-05-15T18:21:15+02:00 Circulation mechanisms responsible for wet or dry summers over Zimbabwe Moven Manjowe Terence Darlington Mushore Juliet Gwenzi Collen Mutasa Electdom Matandirotya Emmanuel Mashonjowa 2018-06-01 https://doi.org/10.3934/environsci.2018.3.154 https://doaj.org/article/3672646a54f64fac9f9745bf0e610157 en eng AIMS Press 2372-0352 doi:10.3934/environsci.2018.3.154 https://doaj.org/article/3672646a54f64fac9f9745bf0e610157 undefined AIMS Environmental Science, Vol 5, Iss 3, Pp 154-172 (2018) Zimbabwe summer rainfall South Atlantic Ocean High South Indian Ocean High Angola Low Pressure envir geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2018 fttriple https://doi.org/10.3934/environsci.2018.3.154 2023-01-22T17:53:01Z Climate change has resulted in increased rainfall variability over many parts of the world including Southern Africa. As such, droughts and floods have become a frequent phenomenon in Zimbabwe and have potential to intensify socio-economic stressors. This study examined possible forcing factors behind the occurrence of extreme summer events using re-analysis datasets. Composite analysis and correlation methods were used to identify circulation mechanisms and their strength in determining rainfall patterns in Zimbabwe. Predominantly northerly airflow in the lower troposphere was found to favor wet while southerly airflow favors dry seasons. Negative geopotential anomalies (minimum of −20 hPa) to the west of Zimbabwe in the middle levels characterize wet summers which swing to positive anomalies (+24 hPa) during dry summers. Positive SST anomalies (maximum of 0.4) exist to the southwest of Madagascar extending to the western shore on the Angola-Namibian border characterize wet summers which swing to negative anomalies (−0.2 ºC) during dry summer seasons. SST anomalies in the South western Indian and South eastern Atlantic oceans are crucial in the determination of the strength of both the South Indian and Atlantic Ocean high pressure systems which in turn control moisture advection and convergence into Zimbabwe during the summer period. If these SST anomalies at lag times of about 3 months can be used to predict the incoming summer circulation patterns then the accuracy of summer seasonal outlook forecasts can be improved. Studying the mechanisms behind drought and flood occurrence is important to the country which is in the process of downscaling regional prediction products to improve the accuracy of seasonal forecasts. These findings are useful in crafting relevant measures to maximize the benefits and minimize the risks of extreme rainfall events. Article in Journal/Newspaper South Atlantic Ocean Unknown Indian AIMS Environmental Science 5 3 154 172 |
institution |
Open Polar |
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op_collection_id |
fttriple |
language |
English |
topic |
Zimbabwe summer rainfall South Atlantic Ocean High South Indian Ocean High Angola Low Pressure envir geo |
spellingShingle |
Zimbabwe summer rainfall South Atlantic Ocean High South Indian Ocean High Angola Low Pressure envir geo Moven Manjowe Terence Darlington Mushore Juliet Gwenzi Collen Mutasa Electdom Matandirotya Emmanuel Mashonjowa Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
topic_facet |
Zimbabwe summer rainfall South Atlantic Ocean High South Indian Ocean High Angola Low Pressure envir geo |
description |
Climate change has resulted in increased rainfall variability over many parts of the world including Southern Africa. As such, droughts and floods have become a frequent phenomenon in Zimbabwe and have potential to intensify socio-economic stressors. This study examined possible forcing factors behind the occurrence of extreme summer events using re-analysis datasets. Composite analysis and correlation methods were used to identify circulation mechanisms and their strength in determining rainfall patterns in Zimbabwe. Predominantly northerly airflow in the lower troposphere was found to favor wet while southerly airflow favors dry seasons. Negative geopotential anomalies (minimum of −20 hPa) to the west of Zimbabwe in the middle levels characterize wet summers which swing to positive anomalies (+24 hPa) during dry summers. Positive SST anomalies (maximum of 0.4) exist to the southwest of Madagascar extending to the western shore on the Angola-Namibian border characterize wet summers which swing to negative anomalies (−0.2 ºC) during dry summer seasons. SST anomalies in the South western Indian and South eastern Atlantic oceans are crucial in the determination of the strength of both the South Indian and Atlantic Ocean high pressure systems which in turn control moisture advection and convergence into Zimbabwe during the summer period. If these SST anomalies at lag times of about 3 months can be used to predict the incoming summer circulation patterns then the accuracy of summer seasonal outlook forecasts can be improved. Studying the mechanisms behind drought and flood occurrence is important to the country which is in the process of downscaling regional prediction products to improve the accuracy of seasonal forecasts. These findings are useful in crafting relevant measures to maximize the benefits and minimize the risks of extreme rainfall events. |
format |
Article in Journal/Newspaper |
author |
Moven Manjowe Terence Darlington Mushore Juliet Gwenzi Collen Mutasa Electdom Matandirotya Emmanuel Mashonjowa |
author_facet |
Moven Manjowe Terence Darlington Mushore Juliet Gwenzi Collen Mutasa Electdom Matandirotya Emmanuel Mashonjowa |
author_sort |
Moven Manjowe |
title |
Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
title_short |
Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
title_full |
Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
title_fullStr |
Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
title_full_unstemmed |
Circulation mechanisms responsible for wet or dry summers over Zimbabwe |
title_sort |
circulation mechanisms responsible for wet or dry summers over zimbabwe |
publisher |
AIMS Press |
publishDate |
2018 |
url |
https://doi.org/10.3934/environsci.2018.3.154 https://doaj.org/article/3672646a54f64fac9f9745bf0e610157 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
AIMS Environmental Science, Vol 5, Iss 3, Pp 154-172 (2018) |
op_relation |
2372-0352 doi:10.3934/environsci.2018.3.154 https://doaj.org/article/3672646a54f64fac9f9745bf0e610157 |
op_rights |
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op_doi |
https://doi.org/10.3934/environsci.2018.3.154 |
container_title |
AIMS Environmental Science |
container_volume |
5 |
container_issue |
3 |
container_start_page |
154 |
op_container_end_page |
172 |
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1766200415099027456 |