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Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania
The structure and variability of inter-annual and intra-seasonal circulation anomalies and their precursors are investigated over northern Tanzania. Area rainfall departures are computed in the period 1960-1990 and wet and dry years are identified. Northern Tanzania experiences bimodal rains centred...
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| Format: | Thesis |
| Language: | English |
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Department of Oceanography
2016
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| _version_ | 1867613224424177664 |
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| access_status_str | Open Access |
| author | Kabanda, Tibangayuka Abbas |
| author2 | Jury, Mark R |
| author_browse | Jury, Mark R Kabanda, Tibangayuka Abbas |
| author_facet | Jury, Mark R Kabanda, Tibangayuka Abbas |
| author_sort | Kabanda, Tibangayuka Abbas |
| collection | Thesis |
| description | The structure and variability of inter-annual and intra-seasonal circulation anomalies and their precursors are investigated over northern Tanzania. Area rainfall departures are computed in the period 1960-1990 and wet and dry years are identified. Northern Tanzania experiences bimodal rains centred on the seasons: March to May (Masika) and October to December (Vuli). Station inter-correlations in Masika are of order +0.4, whereas in Vuli correlations are of order+0.7. Using composite sequences of gridded sea surface temperatures (SST),outgoing longwave radiation (OLR) and winds in the lower- and upper troposphere, the- precursors of flood and drought are assessed. Composites are averaged for the specific season and for periods 2, 4 and 6 months prior; and the historical mean is subtracted to produce anomalies. In this way, evolution of extreme rainfall scenarios is tracked for predictive purposes. The patterns analysed show that when positive SST anomalies persist in the Indian Ocean, sympathetic negative OLR values and local rainfall enhancement are observed. Using pentad (5 day mean) rainfall time series for the area, wet spells are analysed for structure and evolution. ECMWF data for the peak in Vuli rainfall each year from 1986 to 1991 are averaged to form a single composite. The historical mean is subtracted from the composite to produce anomalies for the wet spell and the preceeding pentads. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/21513 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:44.899Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Oceanography |
| publisherStr | Department of Oceanography |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/21513 Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania Kabanda, Tibangayuka Abbas Jury, Mark R Oceanography The structure and variability of inter-annual and intra-seasonal circulation anomalies and their precursors are investigated over northern Tanzania. Area rainfall departures are computed in the period 1960-1990 and wet and dry years are identified. Northern Tanzania experiences bimodal rains centred on the seasons: March to May (Masika) and October to December (Vuli). Station inter-correlations in Masika are of order +0.4, whereas in Vuli correlations are of order+0.7. Using composite sequences of gridded sea surface temperatures (SST),outgoing longwave radiation (OLR) and winds in the lower- and upper troposphere, the- precursors of flood and drought are assessed. Composites are averaged for the specific season and for periods 2, 4 and 6 months prior; and the historical mean is subtracted to produce anomalies. In this way, evolution of extreme rainfall scenarios is tracked for predictive purposes. The patterns analysed show that when positive SST anomalies persist in the Indian Ocean, sympathetic negative OLR values and local rainfall enhancement are observed. Using pentad (5 day mean) rainfall time series for the area, wet spells are analysed for structure and evolution. ECMWF data for the peak in Vuli rainfall each year from 1986 to 1991 are averaged to form a single composite. The historical mean is subtracted from the composite to produce anomalies for the wet spell and the preceeding pentads. 2016-08-24T12:59:45Z 2016-08-24T12:59:45Z 1995 Master Thesis Masters MSc http://hdl.handle.net/11427/21513 eng application/pdf Department of Oceanography Faculty of Science University of Cape Town |
| spellingShingle | Oceanography Kabanda, Tibangayuka Abbas Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| thesis_degree_str | Master's |
| title | Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| title_full | Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| title_fullStr | Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| title_full_unstemmed | Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| title_short | Seasonal and intra-seasonal dynamics and precursors of rainfall over northern Tanzania |
| title_sort | seasonal and intra seasonal dynamics and precursors of rainfall over northern tanzania |
| topic | Oceanography |
| url | http://hdl.handle.net/11427/21513 |
| work_keys_str_mv | AT kabandatibangayukaabbas seasonalandintraseasonaldynamicsandprecursorsofrainfallovernortherntanzania |