Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe

Chibuike Chiedozie Ibebuchi; Itohan-Osa Abu; Chibuike Chiedozie Ibebuchi; Itohan-Osa Abu

doi:10.3934/geosci.2023001

AIMS Geosciences

2023, Volume 9, Issue 1: 1-15. doi: 10.3934/geosci.2023001

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Research article

Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe

Chibuike Chiedozie Ibebuchi ^{1,2
,
,},
Itohan-Osa Abu ³

1.
Department of Geography, Kent State University, Kent, USA
2.
Julius-Maximilians-University of Würzburg, Institute of Geography and Geology, Department of Physical Geography, Am Hubland, 97074 Würzburg, Germany
3.
Julius-Maximilians-University of Würzburg, Institute for Geography and Geology, Department of Remote Sensing, 97074 Würzburg, Germany

Received: 11 August 2022 Revised: 01 October 2022 Accepted: 20 October 2022 Published: 03 November 2022

This study examines how the atmospheric circulation patterns in Africa south of the equator govern the spatial distribution of precipitation in Zimbabwe. The moisture circulation patterns are designated by an ample set of eight classified circulation types (CTs). Here it is shown that all wet CTs over Zimbabwe features enhanced cyclonic/convective activity in the southwest Indian Ocean. Therefore, enhanced moisture availability in the southwest Indian Ocean is necessary for rainfall formation in parts of Zimbabwe. The wettest CT in Zimbabwe is characterized by a ridging South Atlantic Ocean high-pressure, south of South Africa, driving an abundance of southeast moisture fluxes, from the southwest Indian Ocean into Zimbabwe. Due to the proximity of Zimbabwe to the Agulhas and Mozambique warm current, the activity of the ridging South Atlantic Ocean anticyclone is a dominant synoptic feature that favors above-average rainfall in Zimbabwe. Also, coupled with a weaker state of the Mascarene high, it is shown that a ridging South Atlantic Ocean high-pressure, south of South Africa, can be favorable for the southwest movement of tropical cyclones into the eastern coastal landmasses resulting in above-average rainfall in Zimbabwe. The driest CT is characterized by the northward track of the Southern Hemisphere mid-latitude cyclones leading to enhanced westerly fluxes in the southwest Indian Ocean, limiting moist southeast winds into Zimbabwe.
- moisture circulation,
- mid-latitude cyclone,
- southwest Indian Ocean,
- tropical cyclone,
- South Atlantic Ocean anticyclone
Citation: Chibuike Chiedozie Ibebuchi, Itohan-Osa Abu. Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe[J]. AIMS Geosciences, 2023, 9(1): 1-15. doi: 10.3934/geosci.2023001

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Abstract

This study examines how the atmospheric circulation patterns in Africa south of the equator govern the spatial distribution of precipitation in Zimbabwe. The moisture circulation patterns are designated by an ample set of eight classified circulation types (CTs). Here it is shown that all wet CTs over Zimbabwe features enhanced cyclonic/convective activity in the southwest Indian Ocean. Therefore, enhanced moisture availability in the southwest Indian Ocean is necessary for rainfall formation in parts of Zimbabwe. The wettest CT in Zimbabwe is characterized by a ridging South Atlantic Ocean high-pressure, south of South Africa, driving an abundance of southeast moisture fluxes, from the southwest Indian Ocean into Zimbabwe. Due to the proximity of Zimbabwe to the Agulhas and Mozambique warm current, the activity of the ridging South Atlantic Ocean anticyclone is a dominant synoptic feature that favors above-average rainfall in Zimbabwe. Also, coupled with a weaker state of the Mascarene high, it is shown that a ridging South Atlantic Ocean high-pressure, south of South Africa, can be favorable for the southwest movement of tropical cyclones into the eastern coastal landmasses resulting in above-average rainfall in Zimbabwe. The driest CT is characterized by the northward track of the Southern Hemisphere mid-latitude cyclones leading to enhanced westerly fluxes in the southwest Indian Ocean, limiting moist southeast winds into Zimbabwe.

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