Wavelet-derived periodic variability and regional differences of surface ozone in southeastern Nigeria from 2002 to 2023

This study investigates the spatiotemporal variability of surface ozone across Southeastern Nigeria (2002–2023) using Continuous Wavelet Transform (CWT), a time–frequency method that detects localized oscillations and long-term cycles. Ten representative stations were selected to capture inland, northwestern, and near-coastal conditions. Results show ozone variability is dominated by seasonal periodicities (6–12 months), strongly influenced by the West African monsoon, rainfall, humidity, and wind circulation. Inland and northwestern sites (Onicha, Owerri, Awgu) exhibit stronger seasonal power, reflecting heightened monsoon sensitivity, while southern and coastal stations display more stable oscillations moderated by marine influences. Multi-annual cycles (1–5 years) at Ihiala, Arochukwu, and Okigwe suggest additional control from anthropogenic emissions, biomass burning, land-use change, and climate variability. Trend analysis highlights spatial heterogeneity: gradual increases at Ihiala and Ebonyi, slight declines at Owerri and Awgu, and stability at Onicha and Aba. These findings underscore the multi-scale nature of ozone variability shaped by seasonal, interannual, and local drivers, and emphasize the need for location-specific monitoring frameworks that integrats short-term monsoon forcing with longer-term climatic influences to support air quality regulation, public health, and agricultural productivity. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give... [797 chars]