Characteristics of deep moist convection and rainfall in cut-off lows over South Africa

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dc.contributor.advisor Chikoore, H.
dc.contributor.advisor Bopape, M. M.
dc.contributor.advisor Nethengwe, N. S.
dc.contributor.author Muofhe, Tshimbiluni Percy
dc.date 2019
dc.date.accessioned 2019-10-22T12:48:42Z
dc.date.available 2019-10-22T12:48:42Z
dc.date.issued 2019-09-20
dc.identifier.citation Muofhe, Tshimbiluni Percy (2019) Characteristics of deep moist convection and rainfall in cut-off lows over South Africa, University of Venda, South Africa.<http://hdl.handle.net/11602/1499>.
dc.identifier.uri http://hdl.handle.net/11602/1499
dc.description MENVSC en_US
dc.description Department of Geography and Geo-Information Sciences
dc.description.abstract Out of all rain-producing weather systems, cut-off lows (COLs) are linked with the occurrence of high impact rainfall and in some cases short-lived floods which can last for 24 hours over South Africa. This study examined the characteristics associated with the present occurrence of the severe COL systems over South Africa from 2011 to 2017. The accuracy of the 4.4 km Unified Model (UM) which is currently in use for simulating areas of deep moist convection in South Africa was evaluated. The UM simulated geopotential height at 500 hPa as well as the associated 24 hours precipitation which were compared against the daily fields of geopotential height and 6-hourly precipitation from the European Centre for Medium-Range Weather Forecasts (ECMWF). COL events were categorized and analyzed according to the associated surface circulation patterns at 850 hPa. The seasonal distribution and duration of the systems over northern (10°E-33°E //22°-32°S) and southern (10°E-33°E //32°-35°S) regions of the study area were also analyzed. Results show COL systems shifting with season towards the north eastern parts of the country, with an increased number of events during the austral winter season during the study period. Systems which lasted for long time were observed during the austral winter and spring seasons. The UM tends to simulate areas of heavy precipitation accurately with poor simulation during the initial stages of the systems. The UM provided a more realistic-looking closed geopotential height and rainfall fields for systems which are coupled with a cold front at the surface. Application of the knowledge about the evolution in the characteristics of COL events from this study can improve the operational forecasting of these weather systems over the country. en_US
dc.description.sponsorship NRF en_US
dc.format.extent 1 online resource (xiii, 104 leaves : color illustrations, color maps)
dc.language.iso en en_US
dc.rights University of Venda
dc.subject Cut-off lows en_US
dc.subject Circulation en_US
dc.subject Deep moist convection en_US
dc.subject Synoptic patterns en_US
dc.subject Simulation en_US
dc.subject.ddc 551.5770968
dc.subject.lcsh Rain and rainfall -- South Africa
dc.subject.lcsh Precipitation (Meteorology) -- South Africa
dc.subject.lcsh Moisture -- South Africa
dc.title Characteristics of deep moist convection and rainfall in cut-off lows over South Africa en_US
dc.type Dissertation en_US

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