Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean

Like most of the countries in the Great Horn of Africa, Tanzania is prone to floods and droughts. Anomalously wet years over the region are associated with low-level convergence, the advection of moisture from both the Indian Ocean and the Congo and an ascending limb of the Walker circulation cell c...

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Main Authors: Paul Tilwebwa Shelleph Limbu, Guirong Tan
Format: Article
Language:English
Published: Borntraeger 2019-12-01
Series:Meteorologische Zeitschrift
Subjects:
Online Access:http://dx.doi.org/10.1127/metz/2019/0939
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author Paul Tilwebwa Shelleph Limbu
Guirong Tan
author_facet Paul Tilwebwa Shelleph Limbu
Guirong Tan
author_sort Paul Tilwebwa Shelleph Limbu
collection DOAJ
description Like most of the countries in the Great Horn of Africa, Tanzania is prone to floods and droughts. Anomalously wet years over the region are associated with low-level convergence, the advection of moisture from both the Indian Ocean and the Congo and an ascending limb of the Walker circulation cell centered over the western Indian Ocean (WIO). During positive Indian Ocean dipole (IOD) events, the Walker circulation cell over the Indian Ocean is well defined, and more so compared with observed during El Niño years. In El Niño years, the Walker circulation cell becomes weak compared with positive IOD events, where the zonal winds strengthen, resulting in active convective activities over the WIO. A key finding is that the Walker circulation cell developing over the Indian Ocean is strongly connected to IOD activity. The weakening of the Walker circulation cell is likely the reason for the decrease in rainfall during El Niño events compared with that of positive IOD events in recent years over Tanzania during the October–December season. The variability of the Walker circulation cell over the Indian Ocean can lead to extreme weather conditions, making the full understanding of the climate system essential. This is crucial for decision making about adaptation and mitigation measures for coping with climate change and for the minimization of huge socio-economic losses associated with extreme weather events in the region.
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spelling doaj.art-7b3524cde7594ccc8b62e5e63dea23fd2022-12-21T18:37:12ZengBorntraegerMeteorologische Zeitschrift0941-29482019-12-0128645346910.1127/metz/2019/093990485Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian OceanPaul Tilwebwa Shelleph LimbuGuirong TanLike most of the countries in the Great Horn of Africa, Tanzania is prone to floods and droughts. Anomalously wet years over the region are associated with low-level convergence, the advection of moisture from both the Indian Ocean and the Congo and an ascending limb of the Walker circulation cell centered over the western Indian Ocean (WIO). During positive Indian Ocean dipole (IOD) events, the Walker circulation cell over the Indian Ocean is well defined, and more so compared with observed during El Niño years. In El Niño years, the Walker circulation cell becomes weak compared with positive IOD events, where the zonal winds strengthen, resulting in active convective activities over the WIO. A key finding is that the Walker circulation cell developing over the Indian Ocean is strongly connected to IOD activity. The weakening of the Walker circulation cell is likely the reason for the decrease in rainfall during El Niño events compared with that of positive IOD events in recent years over Tanzania during the October–December season. The variability of the Walker circulation cell over the Indian Ocean can lead to extreme weather conditions, making the full understanding of the climate system essential. This is crucial for decision making about adaptation and mitigation measures for coping with climate change and for the minimization of huge socio-economic losses associated with extreme weather events in the region.http://dx.doi.org/10.1127/metz/2019/0939walker circulation cellrainfallindian ocean dipoleel niño–southern oscillationvariabilitytanzania
spellingShingle Paul Tilwebwa Shelleph Limbu
Guirong Tan
Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
Meteorologische Zeitschrift
walker circulation cell
rainfall
indian ocean dipole
el niño–southern oscillation
variability
tanzania
title Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
title_full Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
title_fullStr Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
title_full_unstemmed Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
title_short Relationship between the October–December rainfall in Tanzania and the Walker circulation cell over the Indian Ocean
title_sort relationship between the october december rainfall in tanzania and the walker circulation cell over the indian ocean
topic walker circulation cell
rainfall
indian ocean dipole
el niño–southern oscillation
variability
tanzania
url http://dx.doi.org/10.1127/metz/2019/0939
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AT guirongtan relationshipbetweentheoctoberdecemberrainfallintanzaniaandthewalkercirculationcellovertheindianocean