scholarly journals Forecasting Intense Cut-Off Lows in South Africa Using the 4.4 Km Unified Model

2020 ◽  
Author(s):  
Tshimbiluni Percy Muofhe ◽  
Hector Chikoore ◽  
Mary-Jane Bopape ◽  
Nthaduleni S Nethengwe ◽  
Thando Ndarana ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Heavy Rainfall ◽  
Weather Forecasting ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Unified Model ◽  
Severe Weather ◽  
Economic Activities ◽  
Circulation Patterns

Mid-tropospheric cut-off low (COL) pressure systems are linked to severe weather, heavy rainfall and extreme cold conditions over South Africa. They often result in floods and snowfalls in winter disrupting economic activities. This paper examines the evolution and circulation patterns associated with severe COLs over South Africa. We evaluate the performance of the 4.4 km Unified Model (UM) which is currently used operationally by the South African Weather Service to simulate daily rainfall. Circulation variables and precipitation simulated by the UM were compared against ECMWF’s ERA Interim reanalyses and GPM precipitation at 24-hour timesteps. We present five recent (2016-2019) severe COLs that had high impact and found higher model skill when simulating heavy precipitation during the initial stages than the dissipating stages of the systems. A key finding was that the UM underestimated precipitation mainly due to inaccurate placing of COL centers and areas of heavy rainfall by up to 5° of latitude away from the actual location, due to the poor formulating of cumulus and microphysics schemes in the model. Understanding the performance and limitations of the UM model in simulating COL characteristics can benefit severe weather forecasting and contribute to disaster risk reduction in South Africa.

scholarly journals Forecasting Intense Cut-Off Lows in South Africa Using the 4.4 km Unified Model

Climate ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 129
Author(s):  
Tshimbiluni Percy Muofhe ◽  
Hector Chikoore ◽  
Mary-Jane Morongwa Bopape ◽  
Nthaduleni Samuel Nethengwe ◽  
Thando Ndarana ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Weather Forecasting ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Unified Model ◽  
Severe Weather ◽  
Economic Activities ◽  
Circulation Patterns ◽  
Extreme Cold

Mid-tropospheric cut-off low (COL) pressure systems are linked to severe weather, heavy rainfall and extreme cold conditions over South Africa. They occur during all the above and often result in floods and snowfalls during the winter months, disrupting economic activities and causing extensive damage to infrastructure. This paper examines the evolution and circulation patterns associated with cases of severe COLs over South Africa. We evaluate the performance of the 4.4 km Unified Model (UM) which is currently used operationally by the South African Weather Service (SAWS) to simulate daily rainfall. Circulation variables and precipitation simulated by the UM were compared against European Centre for Medium-Range Weather Forecast’s (ECMWF’s) ERA Interim re-analyses and GPM precipitation at 24-hour timesteps. We present five recent severe COLs, which occurred between 2016 and 2019, that had high impact and found a higher model skill when simulating heavy precipitation during the initial stages than the dissipating stages of the systems. A key finding was that the UM simulated the precipitation differently during the different stages of development and location of the systems. This is mainly due to inaccurate placing of COL centers. Understanding the performance and limitations of the UM model in simulating COL characteristics can benefit severe weather forecasting and contribute to disaster risk reduction in South Africa.

scholarly journals Recognition of prior learning: its relevance to the proposed unified model o f education and training for South African nurses.

Curationis ◽  
2000 ◽  
Vol 23 (2) ◽  
Author(s):  
T Khanyile
Keyword(s):  
South Africa ◽  
South African ◽  
Nurse Educators ◽  
Education And Training ◽  
Unified Model ◽  
Historical Background ◽  
Nurse Training ◽  
Prior Learning ◽  
Recognition Of Prior Learning ◽  
And Training

Recognition of Prior Learning (RPL) is a fairly new concept in South Africa, and hence different people have different views about RPL . Through this paper, an attempt is made to shed some light on the historical background as well as the philosophical and theoretical underpinnings of RPL . It is hoped that this information will help those nurse educators wishing to experiment with RPL to have a better understanding of how the concept came about. The relevance of RPL to the Unified model of nurse training proposed by the South African Nursing Council is also discussed.

Exploring Guanxi in a Cross-Cultural Context

2017 ◽  
Vol 13 (2) ◽  
pp. 263-286 ◽  
Author(s):  
_ _
Keyword(s):  
South Africa ◽  
South African ◽  
Cultural Context ◽  
Cross Cultural ◽  
Economic Activities ◽  
Employment Decisions ◽  
Employment Relationships

Abstract Using a case study of recently arrived Cantonese-speaking migrants, this article examines the role of guanxi in shaping Chinese newcomers’ economic activities and opportunities in South Africa. In Johannesburg, Cantonese-speaking migrants tend to be employed in restaurant and fahfee (gambling) sectors, which are partially inherited from the early generations of South African Chinese. Through narratives and stories, this article reveals that Cantonese newcomers often strengthen personal and employment relationships through the practice of guanxi, but that doing so can also constrain their employment decisions. Moreover, the ambiguous boundary between the act of bribery and the practice of guanxi may facilitate Chinese participation but can also result in the victimization of the newcomers.

Short-term risk forecasts of heavy rainfall

2002 ◽  
Vol 45 (2) ◽  
pp. 121-125 ◽  
Author(s):  
W. Schmid ◽  
S. Mecklenburg ◽  
J. Joss
Keyword(s):  
Probability Distribution ◽  
Density Function ◽  
Heavy Rainfall ◽  
Heavy Precipitation ◽  
Severe Weather ◽  
Short Term ◽  
Radar Images ◽  
Error Density ◽  
Estimated Error ◽  
Near Future

Methodologies for risk forecasts of severe weather hardly exist on the scale of nowcasting (0–3 hours). Here we discuss short-term risk forecasts of heavy precipitation associated with local thunderstorms. We use COTREC/RainCast: a procedure to extrapolate radar images into the near future. An error density function is defined using the estimated error of location of the extrapolated radar patterns. The radar forecast is folded (“smeared”) with the density function, leading to a probability distribution of radar intensities. An algorithm to convert the radar intensities into values of precipitation intensity provides the desired probability (or risk) of heavy rainfall at any position within the considered window in space and time. We discuss, as an example, a flood event from summer 2000.

scholarly journals Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

2020 ◽  
Author(s):  
Frederik Wolf ◽  
Ugur Ozturk ◽  
Kevin Cheung ◽  
Reik V. Donner
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Extreme Weather Events ◽  
Window Approach ◽  
High Level

Abstract. Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. To thoroughly expand on previous works employing the latter framework to the East Asian Summer Monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help to improve future forecasts of the Baiu onset in different regions of East Asia.

scholarly journals Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

2021 ◽  
Vol 12 (1) ◽  
pp. 295-312
Author(s):  
Frederik Wolf ◽  
Ugur Ozturk ◽  
Kevin Cheung ◽  
Reik V. Donner
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Extreme Weather Events ◽  
Window Approach ◽  
High Level

Abstract. Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. To thoroughly expand on previous works employing the latter framework to the East Asian summer monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds, which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help to improve future forecasts of the Baiu onset in different regions of East Asia.

scholarly journals Severe weather over the Highveld of South Africa during November 2016

Water SA ◽  
2018 ◽  
Vol 44 (1 January) ◽  
Author(s):  
Lee-ann Simpson ◽  
Liesl L Dyson
Keyword(s):  
South Africa ◽  
Prediction Models ◽  
Weather Forecast ◽  
Severe Weather ◽  
Severe Thunderstorm ◽  
Weather Events ◽  
Circulation Patterns ◽  
Conditional Instability ◽  
Synoptic Circulation

November months are notorious for severe weather over the Highveld of South Africa. November 2016 was no exception and a large number of severe events occurred. Very heavy rainfall, large hail and tornadoes were reported. The aim of this paper is to compare the synoptic circulation of November 2016 with the long-term mean November circulation and to investigate some sounding derived parameters. Furthermore, a few of the severe weather events are described in detail. The surface temperatures and dewpoint temperatures were found to be higher than normal resulting in increased conditional instability over the Highveld. Low-level moisture originated over the warm Mozambique Channel and the 500 hPa temperature trough was located favourably over the Highveld; further east than normal. The combination of these factors and weak steering winds resulted in flash flooding on the 9th while favourable wind shear conditions caused the development of a tornado on 15 November. The favourable circulation patterns and moisture gave rise to an atmosphere in which severe weather was a possibility, and the awareness of such factors is used as one of many tools when considering the severe weather forecast. The consideration of the daily variables derived from sounding data were good precursors for the prediction of severe thunderstorm development over the Highveld during November 2016. It is recommended that an operational meteorologist incorporates upper air sounding data into the forecasting process and not to rely on numerical prediction models exclusively.

scholarly journals Genetic diversity and molecular epidemiology of respiratory syncytial virus over four consecutive seasons in South Africa: identification of new subgroup A and B genotypes

2001 ◽  
Vol 82 (9) ◽  
pp. 2117-2124 ◽  
Author(s):  
Marietjie Venter ◽  
Shabir A. Madhi ◽  
Caroline T. Tiemessen ◽  
Barry D. Schoub
Keyword(s):  
South Africa ◽  
Respiratory Syncytial Virus ◽  
Molecular Epidemiology ◽  
South African ◽  
Tertiary Hospital ◽  
The Other ◽  
Rt Pcr ◽  
Circulation Patterns ◽  
Group A ◽  
Syncytial Virus

The molecular epidemiology of respiratory syncytial virus (RSV) was studied over four consecutive seasons (1997–2000) in a single tertiary hospital in South Africa: 225 isolates were subgrouped by RT–PCR and the resulting products sequenced. Subgroup A predominated in two seasons, while A and B co-circulated approximately equally in the other seasons. The nucleotide sequences of the C-terminal of the G-protein were compared to sequences representative of previously defined RSV genotypes. South African subgroup A and subgroup B isolates clustered into four and five genotypes respectively. One new subgroup A and three new subgroup B genotypes were identified. Different genotypes co-circulated in every season. Different circulation patterns were identified for group A and B isolates. Subgroup A revealed more variability and displacement of genotypes while subgroup B remained more consistent.

The Macroeconomic Landscape of Post-Apartheid South Africa: A Critical Review of the Effect of the Broad-Based Black Economic Empowerment (BBBEE) Program on the Success of Female SMEs Operators

2017 ◽  
Vol 7 (1) ◽  
pp. 145-150 ◽  
Author(s):  
B.N.O. Irene
Keyword(s):  
South Africa ◽  
South African ◽  
Value Chain ◽  
Deep Understanding ◽  
Black Population ◽  
High Rate ◽  
Business Strategies ◽  
The South ◽  
Economic Activities ◽  
The Impact

Abstract Previous business research has highlighted the impact of government policy in the processes of formulating business strategies and in the decision-making process of organizations. In the South African context, a review of this impact on organizational strategy is for the most part important especially after the fall of apartheid as businesses have been saddled with widespread institutional change the purpose of which is to redress historic inequalities that characterized the apartheid regime. Specifically, the introduction of a far-reaching B-BBEE policy aimed at increasing participation of PIDs in economic activities. Previous researchers have been focused on the impact of B-BBEE policy on mergers and acquisitions, strategic decisions and value chain structures, as well as ROEs. The current report from STATS-SA indicates that the failure rate for women-owned businesses remains at a high rate despite the implementation of the B-BBEE policy. Therefore, research on the impact of BBBEE on business strategy and success of female SMMEs operators may provide an accurate and deep understanding that will be beneficial to policymakers because of the social pressures to emphasis more on a 'broad-based' BEE (B-BBEE) policy aimed at increasing the participation of the black population (and in particular women) in economic activities as well as increasing the number of black ownership in businesses or creating employment for the black population. This study used appropriate data tools and techniques to analyze the data drawn from a sample of female entrepreneurs in South Africa. The study applies culturally instantiated facets of the debate on gender entrepreneurship as part of a detailed and empirically sophisticated consideration of the status of female entrepreneurship within South Africa. This paper involves an in-depth survey using the ten dimensions of business performance as a basis to study small South African women-owned businesses given that the approach is useful in the development of a theory in fields where not much research has been undertaken. The businesses studied for this research are based on a setting where B-BBEE program is a principal factor in the strategic framework of the South African female business owner. This paper contributes to existing literature on the implications of the BBBEE program on SMEs by studying the relationship between business strategies, outcomes, and the B-BBEE program.

scholarly journals A snow forecasting decision tree for significant snowfall over the interior of South Africa

2016 ◽  
Vol Volume 112 (Number 9/10) ◽  
Author(s):  
Jan Hendrik Stander ◽  
Liesl Dyson ◽  
Christien J. Engelbrecht ◽  
◽  
◽  
...  
Keyword(s):  
South Africa ◽  
Decision Tree ◽  
Weather Forecasting ◽  
Second Step ◽  
Loss Of Life ◽  
Surface Conditions ◽  
Circulation Patterns ◽  
Weather Forecasters ◽  
Physical Attributes ◽  
Synoptic Circulation

Abstract Snowfall occurs every winter over the mountains of South Africa but is rare over the highly populated metropolises over the interior of South Africa. When snowfall does occur over highly populated areas, it causes widespread disruption to infrastructure and even loss of life. Because of the rarity of snow over the interior of South Africa, inexperienced weather forecasters often miss these events. We propose a five-step snow forecasting decision tree in which all five criteria must be met to forecast snowfall. The decision tree comprises physical attributes that are necessary for snowfall to occur. The first step recognises the synoptic circulation patterns associated with snow and the second step detects whether precipitation is likely in an area. The remaining steps all deal with identifying the presence of a snowflake in a cloud and determining that the snowflake will not melt on the way to the ground. The decision tree is especially useful to forecast the very rare snow events that develop from relatively dry and warmer surface conditions. We propose operational implementation of the decision tree in the weather forecasting offices of South Africa, as it is foreseen that this approach could significantly contribute to accurately forecasting snow over the interior of South Africa.

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