Statistical analysis of factors driving surface ozone variability over continental South Africa

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Laban , T L , Van Zyl , P G , Beukes , J P , Mikkonen , S , Santana , L , Josipovic , M , Vakkari , V , Thompson , A M , Kulmala , M & Laakso , L 2020 , ' Statistical analysis of factors driving surface ozone variability over continental South Africa ' , Journal of Integrative Environmental Sciences , vol. 17 , no. 3 , pp. 1-28 . https://doi.org/10.1080/1943815X.2020.1768550

Title: Statistical analysis of factors driving surface ozone variability over continental South Africa
Author: Laban, Tracey Leah; Van Zyl, Pieter Gideon; Beukes, Johan Paul; Mikkonen, Santtu; Santana, Leonard; Josipovic, Miroslav; Vakkari, Ville; Thompson, Anne M.; Kulmala, Markku; Laakso, Lauri
Other contributor: University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)

Date: 2020-12-29
Language: eng
Number of pages: 28
Belongs to series: Journal of Integrative Environmental Sciences
ISSN: 1943-815X
DOI: https://doi.org/10.1080/1943815X.2020.1768550
URI: http://hdl.handle.net/10138/322611
Abstract: Statistical relationships between surface ozone (O-3) concentration, precursor species and meteorological conditions in continental South Africa were examined from data obtained from measurement stations in north-eastern South Africa. Three multivariate statistical methods were applied in the investigation, i.e. multiple linear regression (MLR), principal component analysis (PCA) and -regression (PCR), and generalised additive model (GAM) analysis. The daily maximum 8-h moving average O-3 concentrations were considered in these statistical models (dependent variable). MLR models indicated that meteorology and precursor species concentrations are able to explain similar to 50% of the variability in daily maximum O-3 levels. MLR analysis revealed that atmospheric carbon monoxide (CO), temperature and relative humidity were the strongest factors affecting the daily O-3 variability. In summer, daily O-3 variances were mostly associated with relative humidity, while winter O-3 levels were mostly linked to temperature and CO. PCA indicated that CO, temperature and relative humidity were not strongly collinear. GAM also identified CO, temperature and relative humidity as the strongest factors affecting the daily variation of O-3. Partial residual plots found that temperature, radiation and nitrogen oxides most likely have a non-linear relationship with O-3,while the relationship with relative humidity and CO is probably linear. An inter-comparison between O-3 levels modelled with the three statistical models compared to measured O-3 concentrations showed that the GAM model offered a slight improvement over the MLR model. These findings emphasise the critical role of regional-scale O-3 precursors coupled with meteorological conditions in daily variances of O-3 levels in continental South Africa.
Subject: Tropospheric ozone (O-3)
multiple linear regression
principal component analysis
generalized additive models
Welgegund
GROUND-LEVEL OZONE
UNITED-STATES
METEOROLOGICAL CONDITIONS
URBAN AREAS
REGRESSION
MODELS
PARAMETERIZATION
TEMPERATURE
PARTICLES
PATTERNS
114 Physical sciences
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