Emissions of toxic gases and aerosols in southern Africa observed during the 2019 JJASO period
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Emissions of toxic gases and aerosols in southern Africa observed during the 2019 JJASO period Lerato Shikwambana 1,2 Received: 15 May 2020 / Accepted: 5 October 2020 # Springer Nature B.V. 2020
Abstract There are several different types of sources responsible for the emissions of carbon monoxide (CO), sulphur dioxide (SO2), nitrogen dioxide (NO2) and aerosols in Africa. These emissions make the African continent vulnerable to the impacts on climate change, human health and the environment. It has been shown that the southern African emissions are dominant in the winter season (JJA). However, few studies have been done to study the winter and spring season in unison to understand these emissions. Therefore, in this study, both satellite data, such as Sentinel-5P and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), and reanalysis data from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), were used to study emissions in the 2019 JJASO period. Furthermore, the sequential Mann-Kendall (SQMK) test was used to study the trends of SO2, CO, Angstrom exponent and UV aerosol index data during the 2019 JJASO period. The results from sentinel-5P showed the dominance of CO and NO2 in the Democratic Republic of the Congo (DRC) and dominance of SO2 and NO2 in the Republic of South Africa (RSA). These emissions were largely from wildfires and coal-fired power stations, respectively. However, an SO2 hot spot was also observed over the DRC region which was found to be from an active volcano. CALIPSO data agreed with these observations and further showed the maximum vertical distribution of these aerosols and gases to be at ~ 2 km. The SQMK test of Angstrom exponent and UV aerosol index showed that aerosol dominance from emissions change during the JJASO period. Therefore, studying the JJASO period does give a better understanding of emissions in southern Africa. Keywords Biomass burning . Black carbon . Sulphur dioxide . Sequential Mann-Kendall . Sentinel-5p . Emissions
Introduction Africa, like many developed nations, contributes to the emissions of harmful gases and aerosols into the atmosphere. Many studies have shown the dominance of biomass burning emissions (Haywood et al. 2008; Liousse et al. 2010; Shikwambana 2019; Kganyago and Shikwambana 2019) and anthropogenic emissions (Tongwane and Moeletsi 2018; Palmer et al. 2019) in Africa. These studies showed that the main source of biomass burning emissions is from seasonal wildfires, whereas anthropogenic emissions originate mostly from power generation, traffic and industrial processing
* Lerato Shikwambana [email protected] 1
Space Science Directorate, South African National Space Agency, Hermanus 7200, South Africa
2
Schools of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg 2050, South Africa
activities (Lelieveld et al. 2015; Brauer et al. 2016). Furthermore, most of the anthropogenic emissions correlate with high population density such as urban a
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