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Venkataraman Sivakumar
School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4041, South Africa

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Journal article
Published: 19 July 2021 in International Journal of Environmental Research and Public Health
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There are two methods of harvesting sugarcane—manual or mechanical. Manual harvesting requires the burning of the standing sugarcane crop. Burning of the crop results in the emission of aerosols and harmful trace gases into the atmosphere. This work makes use of a long-term dataset (1980–2019) to study (1) the atmospheric spatial and vertical distribution of pollutants; (2) the spatial distribution and temporal change of biomass emissions; and (3) the impact/influence of climatic factors on temporal change in atmospheric pollutant loading and biomass emissions over the Mpumalanga and KwaZulu Natal provinces in South Africa, where sugarcane farming is rife. Black carbon (BC) and sulfur dioxide (SO2) are two dominant pollutants in the JJA and SON seasons due to sugarcane burning. Overall, there was an increasing trend in the emissions of BC, SO2, and carbon dioxide (CO2) from 1980 to 2019. Climatic conditions, such as warm temperature, high wind speed, dry conditions in the JJA, and SON season, favor the intensity and spread of the fire, which is controlled. The emitted pollutants are transported to neighboring countries and can travel over the Atlantic Ocean, as far as ~6600 km from the source site.

ACS Style

Lerato Shikwambana; Xolile Ncipha; Sivakumar Sangeetha; Venkataraman Sivakumar; Paidamwoyo Mhangara. Qualitative Study on the Observations of Emissions, Transport, and the Influence of Climatic Factors from Sugarcane Burning: A South African Perspective. International Journal of Environmental Research and Public Health 2021, 18, 7672 .

AMA Style

Lerato Shikwambana, Xolile Ncipha, Sivakumar Sangeetha, Venkataraman Sivakumar, Paidamwoyo Mhangara. Qualitative Study on the Observations of Emissions, Transport, and the Influence of Climatic Factors from Sugarcane Burning: A South African Perspective. International Journal of Environmental Research and Public Health. 2021; 18 (14):7672.

Chicago/Turabian Style

Lerato Shikwambana; Xolile Ncipha; Sivakumar Sangeetha; Venkataraman Sivakumar; Paidamwoyo Mhangara. 2021. "Qualitative Study on the Observations of Emissions, Transport, and the Influence of Climatic Factors from Sugarcane Burning: A South African Perspective." International Journal of Environmental Research and Public Health 18, no. 14: 7672.

Journal article
Published: 10 May 2021 in Sustainability
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Heat stress-related illness attributed to the changing climate, particularly the more frequent extreme high temperatures, is becoming a theme of public concern, especially in the most vulnerable regions, such as the African continent. Knowledge of the existing research directions and gaps on heat stress and human health is vital for informing future strategic research foci capable of influencing policy development, planning, adaptation, and mitigation efforts. In this regard, a bibliometric analysis was conducted, with an emphasis on Africa, to assess regional research contributions to heat stress impacts on human health. The goals of the study were to review publication growth and patterns of the scientific publications and to identify key players (especially collaborating institutions and countries) and the evolution of research themes on the African continent, while paying attention to global trends and emergent hot topics and methodology of heat stress research. Using the Web of Science (WoS) and Scopus core collection databases, a structured keyword search was undertaken, which yielded 463 and 58 research publications from around the world and Africa, respectively. The retrieved scientific documents, published between 1968 and 2020, were analyzed and visualized using a bibliometric analysis technique and the VOSviewer software tool. The results indicate low statistics and slow scientific growth in publication output, with the highest peak having been reached in 2018, resulting in 13 scientific publications. While global research collaborations are successfully reflected in the literature, there is a considerable gap in understanding heat stress and related collaborations between African countries and international institutions. The review study has identified key opportunities that can benefit Africa through the expansion of the scope of heat stress and human health research on the continent. These opportunities can be achieved by closing the following research gaps: (1) vulnerability assessments within demographic classes, such as the elderly, (2) personal exposure and associated risks, (3) Urban Heat Island (UHI) evaluation for urban environments, and (4) heat adaptation research, which will enable informed and targeted preventive actions that will limit future heat health impacts. The authors opine that the pursuit of such studies will be most impactful if the current knowledge gaps are bridged through transdisciplinary research supported by local, regional, and international collaborators.

ACS Style

Katlego Ncongwane; Joel Botai; Venkataraman Sivakumar; Christina Botai. A Literature Review of the Impacts of Heat Stress on Human Health across Africa. Sustainability 2021, 13, 5312 .

AMA Style

Katlego Ncongwane, Joel Botai, Venkataraman Sivakumar, Christina Botai. A Literature Review of the Impacts of Heat Stress on Human Health across Africa. Sustainability. 2021; 13 (9):5312.

Chicago/Turabian Style

Katlego Ncongwane; Joel Botai; Venkataraman Sivakumar; Christina Botai. 2021. "A Literature Review of the Impacts of Heat Stress on Human Health across Africa." Sustainability 13, no. 9: 5312.

Journal article
Published: 23 November 2020 in Remote Sensing
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Despite a number of studies on biomass burning (BB) emissions in the atmosphere, observation of the associated aerosols and pollutants requires continuous efforts. Brazil, and more broadly Latin America, is one of the most important seasonal sources of BB, particularly in the Amazon region. Uncertainty about aerosol loading in the source regions is a limiting factor in terms of understanding the role of aerosols in climate modelling. In the present work, we investigated the Amazon BB episode that occurred during August 2019 and made the international headlines, especially when the smoke plumes plunged distant cities such as São Paulo into darkness. Here, we used satellite and ground-based observations at different locations to investigate the long-range transport of aerosol plumes generated by the Amazon fires during the study period. The monitoring of BB activity was carried out using fire related pixel count from the moderate resolution imaging spectroradiometer (MODIS) onboard the Aqua and Terra platforms, while the distribution of carbon monoxide (CO) concentrations and total columns were obtained from the infrared atmospheric sounding interferometer (IASI) onboard the METOP-A and METOP-B satellites. In addition, AERONET sun-photometers as well as the MODIS instrument made aerosol optical depth (AOD) measurements over the study region. Our datasets are consistent with each other and highlight AOD and CO variations and long-range transport of the fire plume from the source regions in the Amazon basin. We used the Lagrangian transport model FLEXPART (FLEXible PARTicle) to simulate backward dispersion, which showed good agreement with satellite and ground measurements observed over the study area. The increase in Rossby wave activity during the 2019 austral winter the Southern Hemisphere may have contributed to increasing the efficiency of large-scale transport of aerosol plumes generated by the Amazon fires during the study period.

ACS Style

Hassan Bencherif; Nelson Bègue; Damaris Kirsch Pinheiro; David Du Preez; Jean-Maurice Cadet; Fábio Da Silva Lopes; Lerato Shikwambana; Eduardo Landulfo; Thomas Vescovini; Casper Labuschagne; Jonatan Silva; Vagner Anabor; Pierre-François Coheur; Nkanyiso Mbatha; Juliette Hadji-Lazaro; Venkataraman Sivakumar; Cathy Clerbaux. Investigating the Long-Range Transport of Aerosol Plumes Following the Amazon Fires (August 2019): A Multi-Instrumental Approach from Ground-Based and Satellite Observations. Remote Sensing 2020, 12, 3846 .

AMA Style

Hassan Bencherif, Nelson Bègue, Damaris Kirsch Pinheiro, David Du Preez, Jean-Maurice Cadet, Fábio Da Silva Lopes, Lerato Shikwambana, Eduardo Landulfo, Thomas Vescovini, Casper Labuschagne, Jonatan Silva, Vagner Anabor, Pierre-François Coheur, Nkanyiso Mbatha, Juliette Hadji-Lazaro, Venkataraman Sivakumar, Cathy Clerbaux. Investigating the Long-Range Transport of Aerosol Plumes Following the Amazon Fires (August 2019): A Multi-Instrumental Approach from Ground-Based and Satellite Observations. Remote Sensing. 2020; 12 (22):3846.

Chicago/Turabian Style

Hassan Bencherif; Nelson Bègue; Damaris Kirsch Pinheiro; David Du Preez; Jean-Maurice Cadet; Fábio Da Silva Lopes; Lerato Shikwambana; Eduardo Landulfo; Thomas Vescovini; Casper Labuschagne; Jonatan Silva; Vagner Anabor; Pierre-François Coheur; Nkanyiso Mbatha; Juliette Hadji-Lazaro; Venkataraman Sivakumar; Cathy Clerbaux. 2020. "Investigating the Long-Range Transport of Aerosol Plumes Following the Amazon Fires (August 2019): A Multi-Instrumental Approach from Ground-Based and Satellite Observations." Remote Sensing 12, no. 22: 3846.

Journal article
Published: 11 November 2020 in Atmosphere
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While the stratospheric ozone protects the biosphere against ultraviolet (UV) radiation, tropospheric ozone acts like a greenhouse gas and an indicator of anthropogenic pollution. In this paper, we combined ground-based and satellite ozone observations over Irene site (25.90° S, 28.22° E), one of the most ancient ozone-observing stations in the southern tropics. The dataset is made of daily total columns and weekly profiles of ozone collected over 20 years, from 1998 to 2017. In order to fill in some missing data and split the total column of ozone into a tropospheric and a stratospheric column, we used satellite observations from TOMS (Total Ozone Mapping Spectrometer), OMI (Ozone Monitoring Instrument), and MLS (Microwave Limb Sounder) experiments. The tropospheric column is derived by integrating ozone profiles from an ozonesonde experiment, while the stratospheric column is obtained by subtracting the tropospheric column from the total column (recorded by the Dobson spectrometer), and by assuming that the mesospheric contribution is negligible. Each of the obtained ozone time series was then analyzed by applying the method of wavelet transform, which permitted the determination of the main forcings that contribute to each ozone time series. We then applied the multivariate Trend-Run model and the Mann–Kendall test for trend analysis. Despite the different analytical approaches, the obtained results are broadly similar and consistent. They showed a decrease in the stratospheric column (−0.56% and −1.7% per decade, respectively, for Trend-Run and Mann–Kendall) and an increase in the tropospheric column (+2.37% and +3.6%, per decade, respectively, for Trend-Run and Mann–Kendall). Moreover, the results presented here indicated that the slowing down of the total ozone decline is somewhat due to the contribution of the tropospheric ozone concentration.

ACS Style

Hassan Bencherif; Abdoulwahab Toihir; Nkanyiso Mbatha; Venkataraman Sivakumar; David Du Preez; Nelson Bègue; Gerrie Coetzee. Ozone Variability and Trend Estimates from 20-Years of Ground-Based and Satellite Observations at Irene Station, South Africa. Atmosphere 2020, 11, 1216 .

AMA Style

Hassan Bencherif, Abdoulwahab Toihir, Nkanyiso Mbatha, Venkataraman Sivakumar, David Du Preez, Nelson Bègue, Gerrie Coetzee. Ozone Variability and Trend Estimates from 20-Years of Ground-Based and Satellite Observations at Irene Station, South Africa. Atmosphere. 2020; 11 (11):1216.

Chicago/Turabian Style

Hassan Bencherif; Abdoulwahab Toihir; Nkanyiso Mbatha; Venkataraman Sivakumar; David Du Preez; Nelson Bègue; Gerrie Coetzee. 2020. "Ozone Variability and Trend Estimates from 20-Years of Ground-Based and Satellite Observations at Irene Station, South Africa." Atmosphere 11, no. 11: 1216.

Journal article
Published: 03 June 2020 in Atmosphere
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This study aims to investigate the Stratosphere-Troposphere Exchange (STE) events and ozone changes over Irene (25.5° S, 28.1° E). Twelve years of ozonesondes data (2000–2007, 2012–2015) from Irene station operating in the framework of the Southern Hemisphere Additional Ozonesodes (SHADOZ) was used to study the troposphere (0–16 km) and stratosphere (17–28 km) ozone (O3) vertical profiles. Ozone profiles were grouped into three categories (2000–2003, 2004–2007 and 2012–2015) and average composites were calculated for each category. Fifteen O3 enhancement events were identified over the study period. These events were observed in all seasons (one event in summer, four events in autumn, five events in winter and five events in spring); however, they predominantly occur in winter and spring. The STE events presented here are observed to be influenced by the Southern Hemisphere polar vortex. To strengthen the investigation into STE events, advected potential vorticity maps were used, which were assimilated using Modélisation Isentrope du transport Méso–échelle de l’Ozone Stratosphérique par Advection (MIMOSA) model for the 350 K (~12–13 km) isentropic level. These maps indicated transport of high latitude air masses responsible for the reduction of the O3 mole fractions at the lower stratosphere over Irene which coincides with the enhancement of ozone in the upper troposphere. In general, the stratosphere is dominated by higher Modern Retrospective Analysis for Research Application (MERRA-2) potential vorticity (PV) values compared to the troposphere. However, during the STE events, higher PV values from the stratosphere were observed to intrude the troposphere. Ozone decline was observed from 12 km to 24 km with the highest decline occurring from 14 km to 18 km. An average decrease of 6.0% and 9.1% was calculated from 12 to 24 km in 2004–2007 and 2012–2015 respectively, when compared with 2000–2003 average composite. The observed decline occurred in the upper troposphere and lower stratosphere with winter and spring showing more decline compared with summer and autumn.

ACS Style

Thumeka Mkololo; Nkanyiso Mbatha; Venkataraman Sivakumar; Nelson Bègue; Gerrie Coetzee; Casper Labuschagne. Stratosphere–Troposphere Exchange and O3 Variability in the Lower Stratosphere and Upper Troposphere over the Irene SHADOZ Site, South Africa. Atmosphere 2020, 11, 586 .

AMA Style

Thumeka Mkololo, Nkanyiso Mbatha, Venkataraman Sivakumar, Nelson Bègue, Gerrie Coetzee, Casper Labuschagne. Stratosphere–Troposphere Exchange and O3 Variability in the Lower Stratosphere and Upper Troposphere over the Irene SHADOZ Site, South Africa. Atmosphere. 2020; 11 (6):586.

Chicago/Turabian Style

Thumeka Mkololo; Nkanyiso Mbatha; Venkataraman Sivakumar; Nelson Bègue; Gerrie Coetzee; Casper Labuschagne. 2020. "Stratosphere–Troposphere Exchange and O3 Variability in the Lower Stratosphere and Upper Troposphere over the Irene SHADOZ Site, South Africa." Atmosphere 11, no. 6: 586.

Journal article
Published: 31 May 2020 in Climate
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Trend-Run model was performed to estimate the trend in surface temperatures recorded at 12 sites in Guinea from 1960 to 2016 and to examine the contribution of each climate forcing. The coefficient of determination (R2) calculated varies between 0.60 and 0.90, it provides total information about the simulation capability of the model. The decadal trend values also calculated show an upward trend (between 0.04 °C ± 0.06 °C decade−1 and 0.21 °C ± 0.06 °C decade−1). In addition, forcings’ contributions were quantified, and the annual oscillation (AO) contribution is higher for most of the stations, followed by semiannual oscillation (SAO). Among the forcings, the tropical Northern Atlantic (TNA) contribution is greater than that of the sunspot number (SSN), Niño3.4 and Atlantic Niño (AN). Moreover, the Mann-Kendall test revealed a positive significant trend for all stations except at the Macenta site. Additionally, with sequential Mann-Kendall test, trend turning points were found only for the stations of Mamou, Koundara and Macenta at different dates. The temperature anomalies depict warming episodes (1970s, 1980s, 1984 and 1990s). Since then, the temperature is consistently increasing over the country. A significant warming has been shown, which might be further investigated using these models with additional contributing factors.

ACS Style

René Tato Loua; Hassan Bencherif; Nelson Bègue; Nkanyiso Mbatha; Thierry Portafaix; Alain Hauchecorne; Venkataraman Sivakumar; Zoumana Bamba. Surface Temperature Trend Estimation over 12 Sites in Guinea Using 57 Years of Ground-Based Data. Climate 2020, 8, 68 .

AMA Style

René Tato Loua, Hassan Bencherif, Nelson Bègue, Nkanyiso Mbatha, Thierry Portafaix, Alain Hauchecorne, Venkataraman Sivakumar, Zoumana Bamba. Surface Temperature Trend Estimation over 12 Sites in Guinea Using 57 Years of Ground-Based Data. Climate. 2020; 8 (6):68.

Chicago/Turabian Style

René Tato Loua; Hassan Bencherif; Nelson Bègue; Nkanyiso Mbatha; Thierry Portafaix; Alain Hauchecorne; Venkataraman Sivakumar; Zoumana Bamba. 2020. "Surface Temperature Trend Estimation over 12 Sites in Guinea Using 57 Years of Ground-Based Data." Climate 8, no. 6: 68.

Journal article
Published: 16 March 2020 in Atmosphere
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This paper demonstrates the role of meteorology and air transport in influencing the South African atmospheric CO2 distribution. CO2 data from December 2004 to December 2009 acquired by the Tropospheric Emission Spectrometer (TES) instrument onboard the Aura satellite were used to establish the CO2 vertical distribution at selected regions in South Africa. The Hybrid Single-Particle Lagrangian Integrated Trajectories (HYSPLIT) atmospheric model backward trajectories were used to determine the long-range air transport impacting on South African CO2 atmospheric distribution and to detect the source areas of air masses impacting on South Africa’s atmosphere. The study found that long-range air transport can result in the accumulation or dilution of atmospheric CO2 at various sites in South Africa, depending on the source region and type of air flow. The long-range air transport from different source regions at the upper air level between the 700 and 500 hPa stable layers and the layer above 500 hPa strengthens the inhomogeneity in the vertical distribution of CO2, which is caused by the decoupling effect of the upper air stable layers. This long-range air transport also involves intercontinental air transport.

ACS Style

Xolile G. Ncipha; Venkataraman Sivakumar; Oupa E. Malahlela. The Influence of Meteorology and Air Transport on CO2 Atmospheric Distribution over South Africa. Atmosphere 2020, 11, 287 .

AMA Style

Xolile G. Ncipha, Venkataraman Sivakumar, Oupa E. Malahlela. The Influence of Meteorology and Air Transport on CO2 Atmospheric Distribution over South Africa. Atmosphere. 2020; 11 (3):287.

Chicago/Turabian Style

Xolile G. Ncipha; Venkataraman Sivakumar; Oupa E. Malahlela. 2020. "The Influence of Meteorology and Air Transport on CO2 Atmospheric Distribution over South Africa." Atmosphere 11, no. 3: 287.

Journal article
Published: 05 December 2019 in Journal of Energy in Southern Africa
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This study reports on the performance results of the Baseline Surface Radiation Network (BSRN) quality control procedures applied to the solar radiation data, from September 2013 to December 2017, within the South African Weather Service radiometric network. The overall percentage performance of the SAWS solar radiation network based on BSRN quality control methodology was 97.79%, 93.64%, 91.60% and 92.23% for long wave downward irradiance (LWD), global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI) and direct normal irradiance (DNI), respectively, with operational problems largely dominating the percentage of bad data. The overall average performance of the surface solar radiation dataset – Heliosat data records for the GHI estimation for all stations showed a mean bias deviation of 8.28 Wm-2, a mean absolute deviation of 9.06 Wm-2 and the root mean square deviation of 11.02 Wm-2. The correlation, quantified by the square of correlation coefficient (R2), between ground-based and Heliosat-derived GHI time series was ~0.98. The established network has the potential to provide high quality minute solar radiation data sets (GHI, DHI, DNI and LWD) and auxiliary hourly meteorological parameters vital for scientific and practical applications in renewable energy technologies.

ACS Style

Lucky Ntsangwane; Brighton Mabasa; Venkataraman Sivakumar; Nosipho Zwane; Katlego Ncongwane; Joel Botai. Quality control of solar radiation data within the South African Weather Service solar radiometric network. Journal of Energy in Southern Africa 2019, 30, 51 -63.

AMA Style

Lucky Ntsangwane, Brighton Mabasa, Venkataraman Sivakumar, Nosipho Zwane, Katlego Ncongwane, Joel Botai. Quality control of solar radiation data within the South African Weather Service solar radiometric network. Journal of Energy in Southern Africa. 2019; 30 (4):51-63.

Chicago/Turabian Style

Lucky Ntsangwane; Brighton Mabasa; Venkataraman Sivakumar; Nosipho Zwane; Katlego Ncongwane; Joel Botai. 2019. "Quality control of solar radiation data within the South African Weather Service solar radiometric network." Journal of Energy in Southern Africa 30, no. 4: 51-63.

Journal article
Published: 29 November 2019 in Clean Air Journal
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Atmospheric pollutants that affect human health most significantly are particulate matter (PM2.5) and surface ozone (O3). This paper analysed the long-term temporal trends for PM2.5 and ground level O3 for six air quality monitoring stations in the Vaal Triangle Area of South Africa from 2007 to 2017. Research has been conducted on the short-term temporal trends for PM2.5 concentration and surface O3 concentrations. There are no studies that have focussed on the long-term temporal trends for PM2.5 and O3 in the Vaal Triangle Area of South Africa, because these air quality monitoring stations have only existed for a period of approximately 11 years. The data used in this study is derived from ground-based instruments from the South African Weather Service. Temporal patterns for time of day, days of the week, and seasons were observed for all air quality stations. PM2.5 concentration increased during early mornings and late afternoons, with higher concentration during weekdays than weekends and an increase from late winter through to spring and summer. Surface O3 concentrations peaked during the spring and summer months and during midday when there was maximum sunlight acting as a catalyst for photochemical reactions. The long term trends illustrated that there has been no significant decrease in annual average concentration for PM2.5 in four of the six stations and surface O3 for the six stations in the past 10 years in the Vaal Triangle Area of South Africa.

ACS Style

Kogieluxmie Govender; Venkataraman Sivakumar. A decadal analysis of particulate matter (PM2.5) and surface ozone (O3) over Vaal Priority Area, South Africa. Clean Air Journal 2019, 29, 1 .

AMA Style

Kogieluxmie Govender, Venkataraman Sivakumar. A decadal analysis of particulate matter (PM2.5) and surface ozone (O3) over Vaal Priority Area, South Africa. Clean Air Journal. 2019; 29 (2):1.

Chicago/Turabian Style

Kogieluxmie Govender; Venkataraman Sivakumar. 2019. "A decadal analysis of particulate matter (PM2.5) and surface ozone (O3) over Vaal Priority Area, South Africa." Clean Air Journal 29, no. 2: 1.

Journal article
Published: 18 September 2019 in Journal of Energy in Southern Africa
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Diffuse irradiance is important for the operation of solar-powered devices such as photovoltaics, so it is important to analyse its behaviour under different sky conditions. The primary cause of short-term irradiance variability is clouds. One approach to analyse the diffuse irradiance variation is to use cluster analysis to group together days experiencing similar cloud patterns. A study was carried out to examine the application of k-means clustering to daily cloud data in Durban, South Africa (29.87 °S; 30.98 °E), which revealed four distinct day-time cloud cover (CC) patterns classified as Class I, II, III and IV, corresponding to cloudy, sunny, or a combination of the two. Diffuse irradiance was then correlated with each of the classes to establish corresponding diurnal irradiance patterns and the associated temporal variation. Class I had highest diffuse irradiance variation, followed by Classes III, IV and II. To further investigate the local cloud dynamics, cloud types were also analysed for Classes I−IV. It was found that stratocumulus (low cloud category); altocumulus translucidus, castellanus and altocumulus (middle cloud category); and cirrus fibrates and spissatus (high cloud category), were the most frequently occurring cloud types within the different classes. This study contributes to the understanding of the diurnal diffuse irradiance patterns under the four most frequently occurring CC conditions in Durban. Overall, knowledge of these CC and associated diffuse irradiance patterns is useful for solar plant operators to manage plant output where, depending on the CC condition, the use of back-up devices may be increased or reduced accordingly.

ACS Style

Paulene Govender; Venkataraman Sivakumar. Investigating diffuse irradiance variation under different cloud conditions in Durban, using k-means clustering. Journal of Energy in Southern Africa 2019, 30, 22 -32.

AMA Style

Paulene Govender, Venkataraman Sivakumar. Investigating diffuse irradiance variation under different cloud conditions in Durban, using k-means clustering. Journal of Energy in Southern Africa. 2019; 30 (3):22-32.

Chicago/Turabian Style

Paulene Govender; Venkataraman Sivakumar. 2019. "Investigating diffuse irradiance variation under different cloud conditions in Durban, using k-means clustering." Journal of Energy in Southern Africa 30, no. 3: 22-32.

Journal article
Published: 18 July 2019 in Climate
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The monthly averaged data time series of temperatures and rainfall without interruption of Conakry Airport (9.34° N 13.37° W, Guinea) from 1960 to 2016 were used. Inter-annual and annual changes in temperature and rainfall were investigated. Then, different models: Mann-Kendall Test, Multi-Linear-Regression analysis, Theil-Sen’s slope estimates and wavelet analysis where used for trend analysis and the dependency with these climate forcings. Results showed an increase in temperature with semi-annual and annual cycles. A sharp and abrupt rise in the temperature in 1998 was found. The results of study have shown increasing trends for temperature (about 0.21°/year). A decrease in rainfall (about −8.14 mm/year) is found since the end of 1960s and annual cycle with a maximum value of about 1118.3 mm recorded in August in average. The coherence between the two parameters and climate indices: El Niño 3.4, Atlantic Meridional Mode, Tropical Northern Atlantic and Atlantic Niño, were investigated. Thus, there is a clear need for increased and integrated research efforts in climate parameters variations to improve knowledge in climate change.

ACS Style

René Tato Loua; Hassan Bencherif; Nkanyiso Mbatha; Nelson Bègue; Alain Hauchecorne; Zoumana Bamba; Venkataraman Sivakumar. Study on Temporal Variations of Surface Temperature and Rainfall at Conakry Airport, Guinea: 1960–2016. Climate 2019, 7, 93 .

AMA Style

René Tato Loua, Hassan Bencherif, Nkanyiso Mbatha, Nelson Bègue, Alain Hauchecorne, Zoumana Bamba, Venkataraman Sivakumar. Study on Temporal Variations of Surface Temperature and Rainfall at Conakry Airport, Guinea: 1960–2016. Climate. 2019; 7 (7):93.

Chicago/Turabian Style

René Tato Loua; Hassan Bencherif; Nkanyiso Mbatha; Nelson Bègue; Alain Hauchecorne; Zoumana Bamba; Venkataraman Sivakumar. 2019. "Study on Temporal Variations of Surface Temperature and Rainfall at Conakry Airport, Guinea: 1960–2016." Climate 7, no. 7: 93.

Journal article
Published: 03 January 2019 in Data Science Journal
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ACS Style

Willard Zvarevashe; Symala Krishnannair; Venkataraman Sivakumar. Analysis of Rainfall and Temperature Data Using Ensemble Empirical Mode Decomposition. Data Science Journal 2019, 18, 1 .

AMA Style

Willard Zvarevashe, Symala Krishnannair, Venkataraman Sivakumar. Analysis of Rainfall and Temperature Data Using Ensemble Empirical Mode Decomposition. Data Science Journal. 2019; 18 (1):1.

Chicago/Turabian Style

Willard Zvarevashe; Symala Krishnannair; Venkataraman Sivakumar. 2019. "Analysis of Rainfall and Temperature Data Using Ensemble Empirical Mode Decomposition." Data Science Journal 18, no. 1: 1.

Preprint
Published: 21 August 2018
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Quality control (QC) may be a lengthy and tedious process. As a result, most data users use data from meteorological services without performing data quality checks. The South African Weather Service (SAWS) re-established the national solar radiometric network comprising of 13 new stations within the six climatic zones of the country. This study reports on the performance results of the Baseline Surface Radiation Network (BSRN) QC procedures applied to the solar radiation data within the SAWS radiometric network. The overall percentage performance of the SAWS solar radiation network based on BSRN QC methodology is 97.79%, 93.64%, 91.6% and 92.23% for Long Wave Downward Irradiance (LWD), Global Horizontal Irradiance (GHI), Diffuse Horizontal Irradiance (DHI) and Direct Normal Irradiance (DNI) respectively with operational problems largely dominating the percentage of bad data. The overall average performance of the Surface Solar Radiation Dataset – Heliosat (SARAH) data records for the GHI estimation for all the stations showed a Mean Bias Deviation (MBD) of -8.28 Wm-2, a Mean Absolute Deviation (MAD) of 9.06 Wm-2 and the Root Mean Square Deviation (RMSD) of 11.02 Wm-2. The correlation (quantified by R2) between ground-based and SARAH-derived GHI time series was ~ 0.98. The established network has the potential of providing high quality minute solar radiation data sets (GHI, DHI, DNI and LWD) and auxiliary hourly meteorological parameters vital for scientific and practical applications in renewable energy technologies in South Africa.

ACS Style

Lucky Ntsangwane; Venkataraman Sivakumar; Brighton Mabasa; Nosipho Zwane; Katlego Ncongwane; Joel Botai. Quality Control of Solar Radiation Data within the South African Weather Service Solar Radiometric Network. 2018, 1 .

AMA Style

Lucky Ntsangwane, Venkataraman Sivakumar, Brighton Mabasa, Nosipho Zwane, Katlego Ncongwane, Joel Botai. Quality Control of Solar Radiation Data within the South African Weather Service Solar Radiometric Network. . 2018; ():1.

Chicago/Turabian Style

Lucky Ntsangwane; Venkataraman Sivakumar; Brighton Mabasa; Nosipho Zwane; Katlego Ncongwane; Joel Botai. 2018. "Quality Control of Solar Radiation Data within the South African Weather Service Solar Radiometric Network." , no. : 1.

Journal article
Published: 02 August 2018 in Journal of Atmospheric and Solar-Terrestrial Physics
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The forests of the Southwest Indian Ocean (SWIO) islands States are large carbon sinks. Rapid population growth in these islands is responsible for deforestation, which in turn is the main source of carbon dioxide (CO2) emissions. This study is divided into two parts: The present study (Part 1) describes the seasonal vertical and surface spatial distribution of CO2 over the SWIO islands and the temporal variation of surface CO2 concentrations using data measured by the Tropospheric Emission Spectrometer (TES) on board the Aura Satellite. The CO2 hotspots over these islands were identified and assessed to determine if they were associated with deforestation and forest degradation anthropogenic activities. Areas of minimum or low CO2 atmospheric loading were also identified, and investigated to determine if they coincided with strong sink areas. Atmospheric CO2 concentration was building-up from summer to spring. The spatial extent of CO2 hotspots was found to increase from summer to spring. Over the study region, semi-permanent stable layers at 700 hPa and 500 hPa were shown to separate the troposphere into three layers of CO2. Furthermore, surface CO2 levels over all the study areas were found to be increasing during the period of the investigation. Part 2 of this study demonstrates the influence of meteorology and associated air transport on atmospheric CO2 distribution over the study region.

ACS Style

Xolile Ncipha; V. Sivakumar; S. Rakotondraompiana; H. Bencherif. Study on carbon dioxide atmospheric distribution over the Southwest Indian Ocean islands using satellite data: Part 1 – Climatology and seasonal results. Journal of Atmospheric and Solar-Terrestrial Physics 2018, 179, 569 -579.

AMA Style

Xolile Ncipha, V. Sivakumar, S. Rakotondraompiana, H. Bencherif. Study on carbon dioxide atmospheric distribution over the Southwest Indian Ocean islands using satellite data: Part 1 – Climatology and seasonal results. Journal of Atmospheric and Solar-Terrestrial Physics. 2018; 179 ():569-579.

Chicago/Turabian Style

Xolile Ncipha; V. Sivakumar; S. Rakotondraompiana; H. Bencherif. 2018. "Study on carbon dioxide atmospheric distribution over the Southwest Indian Ocean islands using satellite data: Part 1 – Climatology and seasonal results." Journal of Atmospheric and Solar-Terrestrial Physics 179, no. : 569-579.

Journal article
Published: 01 August 2018 in Journal of Atmospheric and Solar-Terrestrial Physics
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We used Level 3 CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations) averaged monthly data to (1) study the climatology of mean aerosol optical depth (AOD) from 2010 to 2015, (2) to compare the mean AOD for different satellites for the period of 2015 and (3) to study the monthly and seasonal variations of mean AOD and extinction coefficient for the period of 2015. The climatology of mean AOD from 2010 to 2015 showed similar patterns of global mean AOD distribution but showed variation in magnitude. The dominance of mean AOD was observed in the latitudes of 0oN to 40oN. Monthly global mean AOD source regions showed dominance in West Africa, India and East Asia. The highest mean AOD (dust + smoke) for these regions was observed in April while the lowest AOD (dust + smoke) was observed in November. The highest extinction coefficients were observed in the MAM season at latitudes of 50oN and 58oS at altitudes of 0.16 and 0.22 km respectively. The highest aerosols in altitude (6 km) were observed during this season.

ACS Style

Lerato Shikwambana; Venkataraman Sivakumar. Global distribution of aerosol optical depth in 2015 using CALIPSO level 3 data. Journal of Atmospheric and Solar-Terrestrial Physics 2018, 173, 150 -159.

AMA Style

Lerato Shikwambana, Venkataraman Sivakumar. Global distribution of aerosol optical depth in 2015 using CALIPSO level 3 data. Journal of Atmospheric and Solar-Terrestrial Physics. 2018; 173 ():150-159.

Chicago/Turabian Style

Lerato Shikwambana; Venkataraman Sivakumar. 2018. "Global distribution of aerosol optical depth in 2015 using CALIPSO level 3 data." Journal of Atmospheric and Solar-Terrestrial Physics 173, no. : 150-159.

Conference paper
Published: 13 April 2018 in EPJ Web of Conferences
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The fixed LIDAR system at University of KwaZulu-Natal (UKZN) in Durban was installed in 1999 and operated until 2004. In 2004, the system was relocated and operation closed due to various technical and instrument problems. The restructuring of the LIDAR system was initiated in 2013 and it is now used to measure vertical aerosol profiles in the height range 03-25 km. Here, we describe the present system in detail, including technical specifications and results obtained from a recent LIDAR calibration campaign.

ACS Style

Venkataraman Sivakumar. Refurbishment of durban fixed ukzn lidar for atmospheric studies – current status. EPJ Web of Conferences 2018, 176, 05056 .

AMA Style

Venkataraman Sivakumar. Refurbishment of durban fixed ukzn lidar for atmospheric studies – current status. EPJ Web of Conferences. 2018; 176 ():05056.

Chicago/Turabian Style

Venkataraman Sivakumar. 2018. "Refurbishment of durban fixed ukzn lidar for atmospheric studies – current status." EPJ Web of Conferences 176, no. : 05056.

Journal article
Published: 01 January 2018 in IFAC-PapersOnLine
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Rainfall exhibits nonlinear and non-stationary characteristic such that analysis done using linear methods are inconclusive. It is, therefore, necessary to understand the multi-scale variations of the rainfall. In this study, a comparison is done of two different regions which receive two distinct rainfall types. Northeastern to southwestern South Africa receives austral winter rainfall whilst the rest of the country receives austral summer rainfall. The multi-scale rainfall variability is done using data adaptive method, ensemble empirical mode decomposition. Changes of rainfall in both regions exhibited inter-annual and quasi-decadal oscillation. We found that there were distinctive spatial differences in the patterns.

ACS Style

Willard Zvarevashe; Syamala Krishnannair; Venkataraman Sivakumar. Analysis of Austral Summer and Winter Rainfall Variability in South Africa Using Ensemble Empirical Mode Decomposition. IFAC-PapersOnLine 2018, 51, 132 -137.

AMA Style

Willard Zvarevashe, Syamala Krishnannair, Venkataraman Sivakumar. Analysis of Austral Summer and Winter Rainfall Variability in South Africa Using Ensemble Empirical Mode Decomposition. IFAC-PapersOnLine. 2018; 51 (5):132-137.

Chicago/Turabian Style

Willard Zvarevashe; Syamala Krishnannair; Venkataraman Sivakumar. 2018. "Analysis of Austral Summer and Winter Rainfall Variability in South Africa Using Ensemble Empirical Mode Decomposition." IFAC-PapersOnLine 51, no. 5: 132-137.

Journal article
Published: 01 October 2017 in Atmósfera
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ACS Style

Venkataraman Sivakumar; Jeremiah Ayodele Ogunniyi. Ozone climatology and variability over Irene, South Africa determined by ground based and satellite observations. Part 1: Vertical variations in the troposphere and stratosphere. Atmósfera 2017, 30, 337 -353.

AMA Style

Venkataraman Sivakumar, Jeremiah Ayodele Ogunniyi. Ozone climatology and variability over Irene, South Africa determined by ground based and satellite observations. Part 1: Vertical variations in the troposphere and stratosphere. Atmósfera. 2017; 30 (4):337-353.

Chicago/Turabian Style

Venkataraman Sivakumar; Jeremiah Ayodele Ogunniyi. 2017. "Ozone climatology and variability over Irene, South Africa determined by ground based and satellite observations. Part 1: Vertical variations in the troposphere and stratosphere." Atmósfera 30, no. 4: 337-353.

Journal article
Published: 01 January 2006 in Advances in Space Research
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ACS Style

Som Sharma; V. Sivakumar; H. Bencherif; H. Chandra; Y.B. Acharya; A. Jayaraman; P.B. Rao; D. Narayana Rao. A comprehensive study on middle atmospheric thermal structure over a tropic and sub-tropic stations. Advances in Space Research 2006, 37, 2278 -2283.

AMA Style

Som Sharma, V. Sivakumar, H. Bencherif, H. Chandra, Y.B. Acharya, A. Jayaraman, P.B. Rao, D. Narayana Rao. A comprehensive study on middle atmospheric thermal structure over a tropic and sub-tropic stations. Advances in Space Research. 2006; 37 (12):2278-2283.

Chicago/Turabian Style

Som Sharma; V. Sivakumar; H. Bencherif; H. Chandra; Y.B. Acharya; A. Jayaraman; P.B. Rao; D. Narayana Rao. 2006. "A comprehensive study on middle atmospheric thermal structure over a tropic and sub-tropic stations." Advances in Space Research 37, no. 12: 2278-2283.