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31 results on '"Bopape, Mary-Jane M."'

7. Simulation of the eThekwini Heat Island in South Africa

Author

Maisha, Robert T, primary, Ndarana, Thando, additional, Engelbrecht, Francois A, additional, Thatcher, Marcus, additional, Bopape, Mary-Jane M, additional, van der Merwe, Jacobus, additional, Padayachi, Yerdashin, additional, and Masemola, Cecilia, additional

Published
2023
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8. Cut-Off Lows over South Africa: A Review

Author

Xulu, Nkosinathi G., primary, Chikoore, Hector, additional, Bopape, Mary-Jane M., additional, Ndarana, Thando, additional, Muofhe, Tshimbiluni P., additional, Mbokodo, Innocent L., additional, Munyai, Rendani B., additional, Singo, Mukovhe V., additional, Mohomi, Tumelo, additional, Mbatha, Sifiso M. S., additional, and Mdoka, Marshall L., additional

Published
2023
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10. Heatwave Variability and Structure in South Africa during Summer Drought

Author

Mbokodo, Innocent L., primary, Bopape, Mary-Jane M., additional, Ndarana, Thando, additional, Mbatha, Sifiso M. S., additional, Muofhe, Tshimbiluni P., additional, Singo, Mukovhe V., additional, Xulu, Nkosinathi G., additional, Mohomi, Tumelo, additional, Ayisi, Kingsley K., additional, and Chikoore, Hector, additional

Published
2023
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11. Rainfall Simulations of High-Impact Weather in South Africa with the Conformal Cubic Atmospheric Model (CCAM)

Author

Bopape, Mary-Jane M., primary, Engelbrecht, Francois A., additional, Maisha, Robert, additional, Chikoore, Hector, additional, Ndarana, Thando, additional, Lekoloane, Lesetja, additional, Thatcher, Marcus, additional, Mulovhedzi, Patience T., additional, Rambuwani, Gift T., additional, Barnes, Michael A., additional, Mkhwanazi, Musa, additional, and Mphepya, Jonas, additional

Published
2022
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12. Corrigendum: Evaluating South African Weather Service information on Idai tropical cyclone and KwaZulu-Natal flood events

Author

Bopape, Mary-Jane M., primary, Sebego, Ezekiel, additional, Ndarana, Thando, additional, Maseko, Bathobile, additional, Netshilema, Masindi, additional, Gijben, Morne, additional, Landman, Stephanie, additional, Phaduli, Elelwani, additional, Rambuwani, Gift, additional, Van Hemert, Louis, additional, and Mkhwanazi, Musa, additional

Published
2022
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16. Evaluating South African Weather Service information on Idai tropical cyclone and KwaZulu-Natal flood events (with corrigendum)

Author

Bopape, Mary-Jane M., primary, Sebego, Ezekiel, additional, Ndarana, Thando, additional, Maseko, Bathobile, additional, Netshilema, Masindi, additional, Gijben, Morne, additional, Landman, Stephanie, additional, Phaduli, Elelwani, additional, Rambuwani, Gift, additional, Van Hemert, Louis, additional, and Mkhwanazi, Musa, additional

Published
2021
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24. Downstream development associated with two types of ridging South Atlantic Ocean anticyclones over South Africa.

Author

Ndarana, Thando, Lekoloane, Lesetja E., Rammopo, Tsholanang S., Reason, Chris J. C., Bopape, Mary-Jane M., Chikoore, Hector, and Engelbrecht, Francois A.

Subjects
ANTICYCLONES, KINETIC energy, GEOPOTENTIAL height, BAROCLINICITY
Abstract

There are at least two types of ridging South Atlantic Ocean high pressure systems in the South African domain. Type-N events occur north of 40°S and Type-S occur south of this latitude line. This study shows that there is no evidence of surface downstream development in terms of the evolution of eddy kinetic energy and associated ageostrophic geopotential fluxes for both types of ridging high events. Rather, for these systems downstream development is an upper level process. The baroclinic waves associated with the ridging develop from baroclinic instability, by converting eddy available potential energy to eddy kinetic energy. The bulk of the conversion is located at the upstream end of the waves. The downstream trough, which is the part of the wave that influences upward motion over South Africa, develops from the transport of eddy kinetic energy across the trough axis by means of ageostrophic geopotential fluxes. These fluxes are stronger for Type-S events. The absence of downstream development at the surface and the presence of it aloft demonstrates that there are differences in the underlying dynamics in the evolutions of these systems in the vertical. The evolution of eddy kinetic energy associated with baroclinic waves that occur during the ridging events is different from what has been observed for cut-off low pressure systems in the South African domain. [ABSTRACT FROM AUTHOR]

Published
2022
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25. Convective initiation and storm life‐cycles in convection‐permitting simulations of the Met Office Unified Model over South Africa

Author

Keat, Will J., Stein, Thorwald H. M., Phaduli, Elelwani, Landman, Stephanie, Becker, Erik, Bopape, Mary-Jane M., Hanley, Kirsty E., Lean, Humphrey W., and Webster, Stu

Abstract

Convective initiation is a challenge for convection‐permitting models due to its sensitivity to sub‐km processes. We evaluate the representation of convective storms and their initiation over South Africa during four summer months in Met Office Unified Model simulations at 1.5‐km horizontal grid length. Storm size distributions from the model compare well against radar observations, but rainfall in the model is predominantly produced by large storms (50 km in diameter or larger) in the evening, whereas radar observations show most rainfall occurs throughout the afternoon, from storms 10‐50 km in diameter. In all months, modelled maximum number of storm initiations occurs at least 2 hours prior to the radar‐observed maximum. However, the diurnal cycle of rainfall compares well between model and observations, suggesting the numerous storm initiations in the simulations do not produce much rainfall. Modelled storms are generally less intense than in the radar observations, especially in early summer. In February, when tropical influences dominate, the simulated storms are of similar intensity to observed storms. Simulated storms tend to reach their peak intensity in the first 15 minutes after initiation, then gradually become less intense as they grow. In radar observations, storms reach their peak intensity 15‐30 minutes into their life cycle, stay intense as they grow larger, then gradually weaken after they have reached their maximum diameter. Two November case studies of severe convection are analysed in detail. Higher resolution grid length initiates convection slightly earlier (300 m cf. 1.5 km) with the same science settings. Two 1.5‐km simulations that apply more sub‐grid mixing have delayed convective initiation. Analysis of soundings indicates little difference in convective indices, suggesting that differences in convection may be attributed to choices in sub‐grid mixing parameters.

Published
2019

28. Effects of stability functions in a dynamic model convective boundary layer simulation.

Author

Bopape, Mary‐Jane M., Plant, Robert S., Coceal, Omduth, Efstathiou, Georgios A., and Valdivieso, Maria

Subjects
*BOUNDARY layer (Aerodynamics), *DYNAMIC models, *DYNAMIC stability, *ATMOSPHERIC boundary layer, *EDDY viscosity, *CONVECTIVE boundary layer (Meteorology)
Abstract

Dynamic subgrid models are increasingly being used in simulations of the atmospheric boundary layer. We have implemented several variant forms of dynamic models in the UK Met Office Large Eddy Model (MetLEM), including a state‐of‐the‐art Lagrangian‐Averaged‐Scale‐Dependent (LASD) model. The implementation includes optional use of stability functions in the specification of the eddy viscosity and diffusivity, as well as optional use within the dynamic calculation of the Smagorinsky parameter. This paper reports on the behaviour of the LASD model with different choices for the inclusion and treatment of stability functions in convective boundary layer simulations at different resolutions. Results are compared against a high‐resolution Large‐Eddy simulation (LES) and against simulations employing the Smagorinsky–Lilly subgrid model. We conclude that the use of stability functions improves the behaviour of the LASD model in the grey zone regime. Moreover, a careful treatment of the stability functions in the calculation of the dynamic parameters, while attractive theoretically, is found to be unnecessary in practical terms. [ABSTRACT FROM AUTHOR]

Published
2021
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29. Regional projections of extreme apparent temperature days in Africa and the related potential risk to human health

Author

25076426 - Garland, Rebecca Maureen, Garland, Rebecca M., Matooane, Mamopeli, Engelbrecht, Francois A., Bopape, Mary-Jane M., Landman, Willem A., 25076426 - Garland, Rebecca Maureen, Garland, Rebecca M., Matooane, Mamopeli, Engelbrecht, Francois A., Bopape, Mary-Jane M., and Landman, Willem A.

Abstract

Regional climate modelling was used to produce high resolution climate projections for Africa, under a “business as usual scenario”, that were translated into potential health impacts utilizing a heat index that relates apparent temperature to health impacts. The continent is projected to see increases in the number of days when health may be adversely affected by increasing maximum apparent temperatures (AT) due to climate change. Additionally, climate projections indicate that the increases in AT results in a moving of days from the less severe to the more severe Symptom Bands. The analysis of the rate of increasing temperatures assisted in identifying areas, such as the East African highlands, where health may be at increasing risk due to both large increases in the absolute number of hot days, and due to the high rate of increase. The projections described here can be used by health stakeholders in Africa to assist in the development of appropriate public health interventions to mitigate the potential health impacts from climate change

Published
2015

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