scholarly journals Characteristics of hail hazard in South Africa based on satellite detection of convective storms

2021 ◽  
Author(s):  
Heinz Jürgen Punge ◽  
Kristopher M. Bedka ◽  
Michael Kunz ◽  
Sarah D. Bang ◽  
Kyle F. Itterly
Keyword(s):  
South Africa ◽  
Preventive Measures ◽  
Return Periods ◽  
Insurance Pricing ◽  
Convective Storms ◽  
Hail Damage ◽  
Exposure Data ◽  
Spatio Temporal ◽  
Cloud Tops ◽  
Temporal Extent

Abstract. Accurate estimates of hail risk to fixed and mobile assets such as crops, infrastructure and vehicles are required for both insurance pricing and preventive measures. Here we present an event catalog to describe hail hazard in South Africa guided by 14 years of geostationary satellite observations of convective storms. Overshooting cloud tops have been detected, grouped and tracked to describe the spatio-temporal extent of potential hail events. It is found that hail events concentrate mainly in the southeast of the country, along the Highveld and the eastern slopes. Events are most frequent from mid-November through February and peak in the afternoon, between 13 and 17 UTC. Multivariate stochastic modeling of event properties yields an event catalog spanning 25 000 years, aiming to estimate, in combination with vulnerability and exposure data, hail damage for return periods of 200 years.

scholarly journals Validation of the Meteosat storm detection and nowcasting system Cb-TRAM with lightning network data – Europe and South Africa

2013 ◽  
Vol 6 (6) ◽  
pp. 1567-1583 ◽  
Author(s):  
T. Zinner ◽  
C. Forster ◽  
E. de Coning ◽  
H.-D. Betz
Keyword(s):  
South Africa ◽  
South African ◽  
Thermal Emission ◽  
Climatic Conditions ◽  
Probability Of Detection ◽  
Night Time ◽  
Detection Scheme ◽  
Lightning Detection ◽  
Physical Limitations ◽  
Cloud Tops

Abstract. In this paper, recent changes to the Meteosat thunderstorm TRacking And Monitoring algorithm (Cb-TRAM) are presented as well as a validation of Cb-TRAM against data from the European ground-based LIghtning NETwork (LINET) of Nowcast GmbH and the South African Weather Service Lightning Detection Network (SAWS LDN). Validation is conducted along the well-known skill measures probability of detection (POD) and false alarm ratio (FAR) on the basis of Meteosat/SEVIRI pixels as well as on the basis of thunderstorm objects. The values obtained demonstrate specific limitations of Cb-TRAM, as well as limitations of satellite methods in general which are based on thermal emission and solar reflectivity information from thunderstorm cloud tops. Although the climatic conditions and the occurrence of thunderstorms are quite different for Europe and South Africa, quality score values are similar. Our conclusion is that Cb-TRAM provides robust results of well-defined quality for very different climatic regimes. The POD for a thunderstorm with intense lightning is about 80% during the day. The FAR for a Cb-TRAM detection which is not even close to intense lightning is about 50%. If only proximity to any lightning activity is required, FAR is much lower at about 15%. Pixel-based analysis shows that detected thunderstorm object size is not indiscriminately large, but well within physical limitations of the satellite method. Night-time POD and FAR are somewhat worse as the detection scheme does not use the high-resolution visible information during night-time hours. Nowcasting scores show useful values up to approximately 30 min in advance.

scholarly journals Spatio-temporal patterns and movement analysis of pigs from smallholder farms and implications for African swine fever spread, Limpopo province, South Africa

2015 ◽  
Vol 82 (1) ◽  
Author(s):  
Folorunso O. Fasina ◽  
Japhta M. Mokoele ◽  
B. Tom Spencer ◽  
Leo A.M.L. Van Leengoed ◽  
Yvette Bevis ◽  
...  
Keyword(s):  
South Africa ◽  
Smallholder Farmers ◽  
Animal Health ◽  
African Swine Fever ◽  
Limpopo Province ◽  
Small Scale ◽  
Network Analyses ◽  
Critical Control Points ◽  
Spatio Temporal ◽  
Disease Dispersal

Infectious and zoonotic disease outbreaks have been linked to increasing volumes of legal and illegal trade. Spatio-temporal and trade network analyses have been used to evaluate the risks associated with these challenges elsewhere, but few details are available for the pig sector in South Africa. Regarding pig diseases, Limpopo province is important as the greater part of the province falls within the African swine fever control area. Emerging small-scale pig farmers in Limpopo perceived pig production as an important means of improving their livelihood and an alternative investment. They engage in trading and marketing their products with a potential risk to animal health, because the preferred markets often facilitate potential longdistance spread and disease dispersal over broad geographic areas. In this study, we explored the interconnectedness of smallholder pig farmers in Limpopo, determined the weaknesses and critical control points, and projected interventions that policy makers can implement to reduce the risks to pig health. The geo-coordinates of surveyed farms were used to draw maps, links and networks. Predictive risks to pigs were determined through the analyses of trade networks, and the relationship to previous outbreaks of African swine fever was postulated. Auction points were identified as high-risk areas for the spread of animal diseases. Veterinary authorities should prioritise focused surveillance and diagnostic efforts in Limpopo. Early disease detection and prompt eradication should be targeted and messages promoting enhanced biosecurity to smallholder farmers are advocated. The system may also benefit from the restructuring of marketing and auction networks. Since geographic factors and networks can rapidly facilitate pig disease dispersal over large areas, a multi-disciplinary approach to understanding the complexities that exist around the animal disease epidemiology becomes mandatory.

scholarly journals The Production and Consumption of Cultural Villages in South Africa: A Decolonial Epistemic Perspective

2017 ◽  
Vol 43 (2) ◽  
pp. 51-63 ◽  
Author(s):  
Morgan Ndlovu
Keyword(s):  
South Africa ◽  
Third World ◽  
The Third ◽  
The People ◽  
Production And Consumption ◽  
Tourism Studies ◽  
Spatio Temporal ◽  
The Third World ◽  
Epistemic Perspective

While many of the peoples who exist in the ‘spatio-temporal’ construct known as the postcolonial world today are convinced that they have succeeded – through anticolonial and anti-imperial struggles – to defeat colonial domination, the majority of the people of the same part of the world have not yet reaped the freedoms which they aimed to achieve. The question that emerges out of the failure to realise the objectives of anti-colonial and anti-imperial struggles by the people of the Third World after a number of years of absence of juridical-administrative colonial and apartheid systems is to what extent did the people who sought to dethrone colonial domination understand the complexity of the colonial system? And to what end did the ability and/or inability to master the complexity of the colonial system affect the process of decolonization? Through the case study of the production and consumption of cultural villages in South Africa, this article deploys a de-colonial epistemic perspective to reveal, within the context of tourism studies, the complexity of the colonial system and why a truly decolonized postcolonial world has so far eluded the people of the developing world.

Socio-Spatial Practice and Racial Representations in a Changing South Africa

2005 ◽  
Vol 35 (3) ◽  
pp. 444-459 ◽  
Author(s):  
Kevin Durrheim
Keyword(s):  
South Africa ◽  
Spatial Practice ◽  
Running Away ◽  
Racial Representations ◽  
Blacks And Whites ◽  
Spatio Temporal ◽  
Temporal Interactions ◽  
Historical Periods

This article argues (a) that the content of racial representations in South Africa has changed historically, and (b) that these representations are grounded in concrete patterns of spatio-temporal interactions between blacks and whites that have characterised different historical epochs. These arguments are developed by means of a consideration of racial interactions and representations in four historical periods: the early Cape colony, the frontier, apartheid and the contemporary post-apartheid period. The bulk of the discussion concerns the kinds of representations that are being developed and perpetuated in the present desegregated context, where whites experience displacement at the hands of blacks, and blacks experience whites running away from them.

scholarly journals Drought Risk Analysis in the Eastern Cape Province of South Africa: The Copula Lens

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1938 ◽  
Author(s):  
Christina M. Botai ◽  
Joel O. Botai ◽  
Abiodun M. Adeola ◽  
Jaco P. de Wit ◽  
Katlego P. Ncongwane ◽  
...  
Keyword(s):  
South Africa ◽  
Gaussian Copula ◽  
Dependence Structure ◽  
Drought Risk ◽  
Eastern Cape Province ◽  
Return Periods ◽  
Eastern Cape ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Duration And Severity

This research study was carried out to investigate the characteristics of drought based on the joint distribution of two dependent variables, the duration and severity, in the Eastern Cape Province, South Africa. The drought variables were computed from the Standardized Precipitation Index for 6- and 12-month accumulation period (hereafter SPI-6 and SPI-12) time series calculated from the monthly rainfall data spanning the last five decades. In this context, the characteristics of climatological drought duration and severity were based on multivariate copula analysis. Five copula functions (from the Archimedean and Elliptical families) were selected and fitted to the drought duration and severity series in order to assess the dependency measure of the two variables. In addition, Joe and Gaussian copula functions were considered and fitted to the drought duration and severity to assess the joint return periods for the dual and cooperative cases. The results indicate that the dependency measure of drought duration and severity are best described by Tawn copula families. The dependence structure results suggest that the study area exhibited low probability of drought duration and high probability of drought severity. Furthermore, the multivariate return period for the dual case is found to be always longer across all the selected univariate return periods. Based on multivariate analysis, the study area (particularly Buffalo City, OR Tambo and Alfred Zoo regions) is determined to have higher/lower risks in terms of the conjunctive/cooperative multivariate drought risk (copula) probability index. The results of the present study could contribute towards policy and decision making through e.g., formulation of the forward-looking contingent plans for sustainable management of water resources and the consequent applications in the preparedness for and adaptation to the drought risks in the water-linked sectors of the economy.

scholarly journals Progress toward developing a practical societal response to severe convection (2005 EGU Sergei Soloviev Medal Lecture)

2005 ◽  
Vol 5 (5) ◽  
pp. 691-702 ◽  
Author(s):  
C. A. Doswell
Keyword(s):  
Convective Storms ◽  
Temporal Specificity ◽  
Severe Convection ◽  
Societal Response ◽  
Critical Issues ◽  
The Usa ◽  
Degree Of Certainty ◽  
Funding Support ◽  
Spatio Temporal ◽  
Made In

Abstract. A review of severe convection in the context of geophysical hazards is given. Societal responses to geophysical hazards depend, in part, on the ability to forecast the events and the degree of certainty with which forecasts can be made. In particular, the spatio-temporal specificity and lead time of those forecasts are critical issues. However, societal responses to geophysical hazards are not only dependent on forecasting. Even perfect forecasts might not be sufficient for a meaningful societal response without the development of considerable infrastructure to allow a society to respond properly and in time to mitigate the hazard. Geophysical hazards of extreme magnitude are rare events, a fact that tends to make funding support for appropriate preparations difficult to obtain. Focusing on tornadoes as a prototypical hazard from severe convective storms, the infrastructure for dealing with them in the USA is reviewed. Worldwide implications of the experience with severe convective storms in the USA are discussed, with an emphasis on its relevance to the situation in Europe.

scholarly journals Q fever seroprevalence in Australia suggests one in twenty people have been exposed

2020 ◽  
Vol 148 ◽  
Author(s):  
H. F. Gidding ◽  
C. Q. Peng ◽  
S. Graves ◽  
P. D. Massey ◽  
C. Nguyen ◽  
...  
Keyword(s):  
Preventive Measures ◽  
Population Distribution ◽  
Q Fever ◽  
Wide Distribution ◽  
Igg Antibody ◽  
Serum Dilution ◽  
Metropolitan Regions ◽  
Exposure Data ◽  
And Gender ◽  
Country Specific

Abstract Q fever (caused by Coxiella burnetii) is thought to have an almost world-wide distribution, but few countries have conducted national serosurveys. We measured Q fever seroprevalence using residual sera from diagnostic laboratories across Australia. Individuals aged 1–79 years in 2012–2013 were sampled to be proportional to the population distribution by region, distance from metropolitan areas and gender. A 1/50 serum dilution was tested for the Phase II IgG antibody against C. burnetii by indirect immunofluorescence. We calculated crude seroprevalence estimates by age group and gender, as well as age standardised national and metropolitan/non-metropolitan seroprevalence estimates. Of 2785 sera, 99 tested positive. Age standardised seroprevalence was 5.6% (95% confidence interval (CI 4.5%–6.8%), and similar in metropolitan (5.5%; 95% CI 4.1%–6.9%) and non-metropolitan regions (6.0%; 95%CI 4.0%–8.0%). More males were seropositive (6.9%; 95% CI 5.2%–8.6%) than females (4.2%; 95% CI 2.9%–5.5%) with peak seroprevalence at 50–59 years (9.2%; 95% CI 5.2%–13.3%). Q fever seroprevalence for Australia was higher than expected (especially in metropolitan regions) and higher than estimates from the Netherlands (2.4%; pre-outbreak) and US (3.1%), but lower than for Northern Ireland (12.8%). Robust country-specific seroprevalence estimates, with detailed exposure data, are required to better understand who is at risk and the need for preventive measures.

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