On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape
This study investigates circulation types (CTs) in Africa, south of the equator, that are related to wet and dry conditions in the Western Cape, the statistical relationship between the selected CTs and the Southern Annular Mode (SAM), and changes in the frequency of occurrence of the CTs related to...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/12/6/753 |
| _version_ | 1827690066640633856 |
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| author | Chibuike Chiedozie Ibebuchi |
| author_facet | Chibuike Chiedozie Ibebuchi |
| author_sort | Chibuike Chiedozie Ibebuchi |
| collection | DOAJ |
| description | This study investigates circulation types (CTs) in Africa, south of the equator, that are related to wet and dry conditions in the Western Cape, the statistical relationship between the selected CTs and the Southern Annular Mode (SAM), and changes in the frequency of occurrence of the CTs related to the SAM under the ssp585 scenario. Obliquely rotated principal component analysis applied to sea level pressure (SLP) was used to classify CTs in Africa, south of the equator. Three CTs were found to have a high probability of being associated with wet days in the Western Cape, and four CTs were equally found to have a high probability of being associated with dry days in the Western Cape. Generally, the dry/wet CTs feature the southward/northward track of the mid-latitude cyclone, adjacent to South Africa; anti-cyclonic/cyclonic relative vorticity, and poleward/equatorward track of westerlies, south of South Africa. One of the selected wet CTs was significantly related to variations of the SAM. Years with an above-average SAM index correlated with the below-average frequency of occurrences of the wet CT. The results suggest that through the dynamics of the CT, the SAM might control the rainfall variability of the Western Cape. Under the ssp585 scenario, the analyzed climate models indicated a possible decrease in the frequency of occurrence of the aforementioned wet CT associated with cyclonic activity in the mid-latitudes, and an increase in the frequency of the occurrence of CT associated with enhanced SLP at mid-latitudes. |
| first_indexed | 2024-03-10T10:32:12Z |
| format | Article |
| id | doaj.art-5db9eb6874684d26a7c64d807eef3210 |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-10T10:32:12Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-5db9eb6874684d26a7c64d807eef32102023-11-21T23:33:58ZengMDPI AGAtmosphere2073-44332021-06-0112675310.3390/atmos12060753On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western CapeChibuike Chiedozie Ibebuchi0Institute of Geography and Geology, University of Würzburg, Am Hubland, 97074 Würzburg, GermanyThis study investigates circulation types (CTs) in Africa, south of the equator, that are related to wet and dry conditions in the Western Cape, the statistical relationship between the selected CTs and the Southern Annular Mode (SAM), and changes in the frequency of occurrence of the CTs related to the SAM under the ssp585 scenario. Obliquely rotated principal component analysis applied to sea level pressure (SLP) was used to classify CTs in Africa, south of the equator. Three CTs were found to have a high probability of being associated with wet days in the Western Cape, and four CTs were equally found to have a high probability of being associated with dry days in the Western Cape. Generally, the dry/wet CTs feature the southward/northward track of the mid-latitude cyclone, adjacent to South Africa; anti-cyclonic/cyclonic relative vorticity, and poleward/equatorward track of westerlies, south of South Africa. One of the selected wet CTs was significantly related to variations of the SAM. Years with an above-average SAM index correlated with the below-average frequency of occurrences of the wet CT. The results suggest that through the dynamics of the CT, the SAM might control the rainfall variability of the Western Cape. Under the ssp585 scenario, the analyzed climate models indicated a possible decrease in the frequency of occurrence of the aforementioned wet CT associated with cyclonic activity in the mid-latitudes, and an increase in the frequency of the occurrence of CT associated with enhanced SLP at mid-latitudes.https://www.mdpi.com/2073-4433/12/6/753Western CapeSouthern Annular Modecirculation typeAfrica south of the equatormid-latitude cyclone |
| spellingShingle | Chibuike Chiedozie Ibebuchi On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape Atmosphere Western Cape Southern Annular Mode circulation type Africa south of the equator mid-latitude cyclone |
| title | On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape |
| title_full | On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape |
| title_fullStr | On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape |
| title_full_unstemmed | On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape |
| title_short | On the Relationship between Circulation Patterns, the Southern Annular Mode, and Rainfall Variability in Western Cape |
| title_sort | on the relationship between circulation patterns the southern annular mode and rainfall variability in western cape |
| topic | Western Cape Southern Annular Mode circulation type Africa south of the equator mid-latitude cyclone |
| url | https://www.mdpi.com/2073-4433/12/6/753 |
| work_keys_str_mv | AT chibuikechiedozieibebuchi ontherelationshipbetweencirculationpatternsthesouthernannularmodeandrainfallvariabilityinwesterncape |