Wavelet-based Insights Into Ozone Dynamics in Southeastern Nigeria (2002–2023): Periodicities, Long-term Trends, and Regional Differences

Comprehending the temporal dynamics of surface ozone is essential for managing air quality, evaluating climate change, and safeguarding public health, especially in the constantly changing Global South. Using the Continuous Wavelet Transform (CWT) to address periodicities, long-term trends, and regional variations in surface ozone behavior, this study examines the spatiotemporal variability of surface ozone concentrations in southeast Nigeria from 2002 to 2023. To capture the region's inland and near-coastal air conditions, ten typical stations—Onicha, Ihiala, Ebonyi, Owerri, Arochukwu, Awgu, Aba, Okigwe, Nsukka, and Anyametum—were examined. The West African monsoon system, wet-dry seasonal transitions, and related meteorological processes like rainfall, humidity, and regional wind circulation all have a significant impact on ozone variability, according to the CWT analysis, which shows that seasonal periodicities (6 months to 1 year) predominate across most stations. Stronger and more noticeable seasonal power is seen at inland and northwestern locations, especially Onicha, Owerri, and Awgu, suggesting increased susceptibility to monsoon-driven climate forcing. On the other hand, southern and near-coastal regions like Aba and Nsukka exhibit comparatively stable seasonal oscillations with less inter-annual variability; this is probably due to marine effects and more stable atmospheric conditions. A number of stations, such as Ihiala, Arochukwu, and Okigwe, exhibit multi-annual periodicities (1–5 years) in addition to seasonal cycles, indicating the impact of longer-term environmental variables such changing land use, changing human emissions, and regional climate variability. These prolonged oscillations suggest that ozone reactions are more complicated than short-term weather changes. Spatial heterogeneity is further revealed by long-term trend analysis: Ihiala and Ebonyi show gradual changes in ozone levels, Owerri and Awgu show modest downward trends, and Onicha and Aba show relatively stable ozone behavior over the study period, possibly reflecting changes in local emission sources or air-quality conditions. Overall, the findings show clear regional differences in ozone dynamics throughout southeast Nigeria, highlighting the fact that seasonal climate forcing, long-term environmental changes, and location-specific factors interact to control ozone variability. The use of wavelet analysis highlights the significance of taking into account both seasonal and inter-annual variability in ozone monitoring and modeling efforts and offers a solid foundation for separating these multi-scale phenomena. These results add to the expanding canon of research on ozone dynamics in tropical and sub-Saharan environments and provide insightful information for region-specific air quality management methods.