Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation

Nitrogen oxides, particularly NO<sub>2</sub>, are emitted through a variety of industrial and transport processes globally. The world’s continuous economic development, including in developing countries, results in an increasing concentration of those gases in the atmosphere. Yet, there...

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Main Authors: Refilwe F. Kai-Sikhakhane, Mary C. Scholes, Stuart J. Piketh, Jos van Geffen, Rebecca M. Garland, Henno Havenga, Robert J. Scholes
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/15/10/1187
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author Refilwe F. Kai-Sikhakhane
Mary C. Scholes
Stuart J. Piketh
Jos van Geffen
Rebecca M. Garland
Henno Havenga
Robert J. Scholes
author_facet Refilwe F. Kai-Sikhakhane
Mary C. Scholes
Stuart J. Piketh
Jos van Geffen
Rebecca M. Garland
Henno Havenga
Robert J. Scholes
author_sort Refilwe F. Kai-Sikhakhane
collection DOAJ
description Nitrogen oxides, particularly NO<sub>2</sub>, are emitted through a variety of industrial and transport processes globally. The world’s continuous economic development, including in developing countries, results in an increasing concentration of those gases in the atmosphere. Yet, there is scant information on the current state and recent evolution of these atmospheric pollutants over a range of spatial and temporal scales, especially in Africa. This, in turn, hinders the assessment of the emissions and the evaluation of potential risks or impacts on societies and their economies, as well as on the environment. This study attempts to fill the gap by leveraging data from a Pandora-2S ground-based, column-integrating instrument located in Wakkerstroom in the Mpumalanga Province of South Africa and space-based remote sensing data obtained from the TROPOMI instrument onboard the ESA Sentinel-5P satellite. We compare these two spatially (horizontal) representative data sets using statistical tools to investigate the concentrations of emitted and transported NO<sub>2</sub> at this particular location, expecting that a significant positive correlation between the NO<sub>2</sub> tropospheric vertical column (TVC) data might justify using the TROPOMI data, available globally, as a proxy for tropospheric and boundary layer NO<sub>2</sub> concentrations over the Highveld of South Africa more generally. The data from the two instruments showed no significant difference between the interannual mean TVC-NO<sub>2</sub> in 2020 and 2021. The seasonal patterns for both instruments were different in 2020, but in 2021, both measured peak TVC-NO<sub>2</sub> concentrations in late winter (week 34). The instruments both detected higher TVC-NO<sub>2</sub> concentrations during transitions between seasons, particularly from winter to spring. The TVC-NO<sub>2</sub> concentrations measured in Wakkerstroom Mpumalanga are mostly contributed to by the emission sources in the low troposphere, such as biomass burning and emissions from local power stations.
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spelling doaj-art-d8ef2fbd5b1f480297440970e63256532025-08-20T02:11:08ZengMDPI AGAtmosphere2073-44332024-10-011510118710.3390/atmos15101187Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P EvaluationRefilwe F. Kai-Sikhakhane0Mary C. Scholes1Stuart J. Piketh2Jos van Geffen3Rebecca M. Garland4Henno Havenga5Robert J. Scholes6School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg 2001, South AfricaSchool of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg 2001, South AfricaUnit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South AfricaRoyal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730 AE De Bilt, The NetherlandsDepartment of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria 0028, South AfricaUnit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South AfricaGlobal Change Institute, University of the Witwatersrand, Johannesburg 2001, South AfricaNitrogen oxides, particularly NO<sub>2</sub>, are emitted through a variety of industrial and transport processes globally. The world’s continuous economic development, including in developing countries, results in an increasing concentration of those gases in the atmosphere. Yet, there is scant information on the current state and recent evolution of these atmospheric pollutants over a range of spatial and temporal scales, especially in Africa. This, in turn, hinders the assessment of the emissions and the evaluation of potential risks or impacts on societies and their economies, as well as on the environment. This study attempts to fill the gap by leveraging data from a Pandora-2S ground-based, column-integrating instrument located in Wakkerstroom in the Mpumalanga Province of South Africa and space-based remote sensing data obtained from the TROPOMI instrument onboard the ESA Sentinel-5P satellite. We compare these two spatially (horizontal) representative data sets using statistical tools to investigate the concentrations of emitted and transported NO<sub>2</sub> at this particular location, expecting that a significant positive correlation between the NO<sub>2</sub> tropospheric vertical column (TVC) data might justify using the TROPOMI data, available globally, as a proxy for tropospheric and boundary layer NO<sub>2</sub> concentrations over the Highveld of South Africa more generally. The data from the two instruments showed no significant difference between the interannual mean TVC-NO<sub>2</sub> in 2020 and 2021. The seasonal patterns for both instruments were different in 2020, but in 2021, both measured peak TVC-NO<sub>2</sub> concentrations in late winter (week 34). The instruments both detected higher TVC-NO<sub>2</sub> concentrations during transitions between seasons, particularly from winter to spring. The TVC-NO<sub>2</sub> concentrations measured in Wakkerstroom Mpumalanga are mostly contributed to by the emission sources in the low troposphere, such as biomass burning and emissions from local power stations.https://www.mdpi.com/2073-4433/15/10/1187Pandora-2snitrogen dioxideTROPOMISentinel-5Pair qualityvalidation
spellingShingle Refilwe F. Kai-Sikhakhane
Mary C. Scholes
Stuart J. Piketh
Jos van Geffen
Rebecca M. Garland
Henno Havenga
Robert J. Scholes
Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
Atmosphere
Pandora-2s
nitrogen dioxide
TROPOMI
Sentinel-5P
air quality
validation
title Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
title_full Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
title_fullStr Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
title_full_unstemmed Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
title_short Assessing Nitrogen Dioxide in the Highveld Troposphere: Pandora Insights and TROPOMI Sentinel-5P Evaluation
title_sort assessing nitrogen dioxide in the highveld troposphere pandora insights and tropomi sentinel 5p evaluation
topic Pandora-2s
nitrogen dioxide
TROPOMI
Sentinel-5P
air quality
validation
url https://www.mdpi.com/2073-4433/15/10/1187
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