Statistical classification of South African seasonal divisions on the basis of daily temperature data

Walt, Adriaan J. van der; Fitchett, Jennifer M.

doi:10.17159/sajs.2020/7614

Cited by 33 publications

(16 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Across South Africa, seasonality influences a wide range of activities that contribute largely to the economy; however, there is little consensus on the timing of seasonal boundaries [38][39][40][41][42][43]. This is due to the inconsistencies in different ad hoc approaches to defining seasonal boundaries across South Africa [44]. The NICD [7] states that for the past thirteen years, the South African flu season has lasted for approximately 19 weeks.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Defining the South African Acute Respiratory Infectious Disease Season

Motlogeloa

Fitchett

Sweijd

2023

IJERPH

View full text Add to dashboard Cite

The acute respiratory infectious disease season, or colloquially the “flu season”, is defined as the annually recurring period characterized by the prevalence of an outbreak of acute respiratory infectious diseases. It has been widely agreed that this season spans the winter period globally, but the precise timing or intensity of the season onset in South Africa is not well defined. This limits the efficacy of the public health sector to vaccinate for influenza timeously and for health facilities to synchronize efficiently for an increase in cases. This study explores the statistical intensity thresholds in defining this season to determine the start and finish date of the acute respiratory infectious disease season in South Africa. Two sets of data were utilized: public-sector hospitalization data that included laboratory-tested RSV and influenza cases and private-sector medical insurance claims under ICD 10 codes J111, J118, J110, and J00. Using the intensity threshold methodology proposed by the US CDC in 2017, various thresholds were tested for alignment with the nineteen-week flu season as proposed by the South African NICD. This resulted in varying thresholds for each province. The respiratory disease season commences in May and ends in September. These findings were seen in hospitalization cases and medical insurance claim cases, particularly with influenza-positive cases in Baragwanath hospital for the year 2019. These statistically determined intensity thresholds and timing of the acute respiratory infectious disease season allow for improved surveillance and preparedness among the public and private healthcare.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Based on the above findings, it is clear that the acute respiratory disease season is most intense during the winter season. Each province had different thresholds; however, all of them increased in the fall and winter based on Van der Walt and Fitchett's [44] seasons classification. These thresholds vary significantly across provinces.…”

Section: Discussionmentioning

confidence: 99%

Defining the South African Acute Respiratory Infectious Disease Season

Motlogeloa

Fitchett

Sweijd

2023

IJERPH

View full text Add to dashboard Cite

show abstract

“…This study examines and compares trends in extreme cold temperature indices on an annual and seasonal timescale. The seasons are defined according to the astronomical divisions: summer encompassing December through January, autumn spanning March through May, winter from June to August and spring from September to November (Van der Walt and Fitchett, 2020).…”

Section: Methodsmentioning

confidence: 99%

Trend analysis of cold extremes in South Africa: 1960–2016

Walt

Fitchett

2020

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

Extreme cold events (“cold waves”) have disastrous impacts on ecosystem and human health. Evidence shows that these events will still occur under current increasing mean temperatures. Little research has been done on extreme cold events, especially in developing countries such as South Africa. These events pose a significant threat due to the low adaptive capacity, urgent development needs and relatively inadequate infrastructure in South Africa. This study presents annual and seasonal, spatial and temporal trend analyses of extreme cold temperature events for the period 1960–2016. We apply the World Meteorological Organisation Commission for Climatology and Indices Expert Team on Sector‐Specific Climate Indices (ET‐SCI) to South Africa for the first time, with comparison to the World Meteorological Organisation Expert Team on Climate Change Detection (ETCCDI) indices previously used in South Africa. The extreme cold indices are calculated using the RClimDex and ClimPACT, respectively. Trends were calculated using the non‐parametric Mann‐Kendall test, Spearman Rank Correlation Coefficient and Sen's slope estimates. A decreasing trend is found for annual cold spell duration and cold wave frequency, at rates of 0.10 days.day−1 and 0.02 events.day−1, respectively. Seasonally, coldest day temperatures increased in autumn, with increases of 0.02°C.day−1 for the period 1960–2016. Regionally, increasing trends in annual cold spell duration days were evident in stations located in the Western Cape, Eastern Cape, North‐West Province, at a rate of 0.03 days.day−1. Increasing trends in cold waves were observed for stations in Northern Cape, Gauteng, KwaZulu‐Natal and the Eastern Cape Province, at a rate of 0.01 events.day−1. These results contribute to the awareness and recognition of the incidence and duration of cold extreme events in South Africa, seeing that studies suggest that anomalously cold events may persist in a warming world.

show abstract

“…It was decided to use the two available sioutas to collect PM samples for OC and EC analysis, as well as the health tests during this campaign. These summer sampling periods can be considered representative of summer, since a recent study indicated that October to March can be classified as summer months in South Africa ( Van der Walt and Fitchett, 2020).…”

Section: Sample Collectionmentioning

confidence: 99%

Measurement report: Size-resolved chemical characterisation of aerosols in low-income urban settlements in South Africa

Segakweng

Zyl

Liousse

et al. 2022

Preprint

View full text Add to dashboard Cite

Abstract. Naturally and anthropogenically emitted aerosols, which are determined by their physical and chemical properties, have an impact on both air quality and the radiative properties of the earth. An important source of atmospheric particulate matter (PM) in South Africa is household combustion for space heating and cooking, which predominantly occurs in low-income urban settlements. The aim of this study was to conduct a detailed size-resolved assessment of chemical characteristics of aerosols associated with household combustion through the collection of particulates in low-income urban settlements in South Africa in order to quantify the extent of the impacts of atmospheric pollution within these settlements. Outdoor (ambient) and indoor aerosols in different size fractions were collected during summer and winter in four low-income urban settlements located in the north-eastern interior on the South African Highveld. The mass concentration and chemical composition was determined for three size fractions, namely, PM1, PM2.5 and PM2.5-10. The highest concentrations of particulates were measured indoors with the highest mass concentration determined in the indoor PM2.5-10 (coarse) size fraction. However, the highest mass concentrations were determined in PM1 in all outdoor aerosol samples collected during winter and summer, as well as in indoor samples collected during summer. Significantly higher concentrations were determined for SO4−2 in outdoor and indoor particulates compared to other ionic species, with NH4+ and NO3− being the second most abundant. SO4−2 and NH4+ almost exclusively occurred in the PM1 size fraction, while NO3− was the major constituent in the larger size fractions. The highest SO4−2 levels were recorded for the winter and summer outdoor campaigns conducted at Zamdela, while NO3− and NH4+ concentrations were higher during the winter outdoor campaign. The combined concentrations of trace elements were higher for indoor particulates compared to outdoor aerosols, while the total trace element concentrations in PM1 were substantially higher than levels thereof in the two larger size fractions of particulates collected during all sampling campaigns. No distinct seasonal trend was observed for the concentrations of trace elements. Na, Ca and Cr had the highest concentrations in particulates collected during outdoor and indoor sampling campaigns. Ni concentrations in outdoor and indoor aerosols exceeded the annual average European standard PM1 collected during all sampling campaigns in low-income urban settlements had the highest organic- and elemental carbon (OC and EC) concentrations. The highest OC and EC levels were determined in PM1 collected during the winter indoor campaign. OC and EC concentrations were highest during winter, which can be attributed to changes in meteorological patterns and increased household combustion during winter. Low OC / EC ratios determined for particulates collected in low-income urban settlements are indicative of OC and EC being mainly associated with local sources of these species. OC concentrations determined in this study were an order of magnitude lower than OC concentrations determined for ambient aerosols collected in the north-eastern interior of South Africa, while similar EC levels were measured. According to estimated dust concentrations, it was indicated that dust is the major constituent in all size ranges of particulates collected in this study, while trace elements were the second most abundant. However, trace elements made the highest contribution to indoor PM1 and PM1-2.5 mass. Mass concentrations and chemical concentrations determined for aerosols collected in low-income settlements reflects the regional impacts of anthropogenic sources in the north-eastern interior of South Africa, as well as the influence of local sources.

show abstract

Statistical classification of South African seasonal divisions on the basis of daily temperature data

Cited by 33 publications

References 45 publications

Defining the South African Acute Respiratory Infectious Disease Season

Defining the South African Acute Respiratory Infectious Disease Season

Trend analysis of cold extremes in South Africa: 1960–2016

Measurement report: Size-resolved chemical characterisation of aerosols in low-income urban settlements in South Africa

Contact Info

Product

Resources

About