Hierarchical Bayesian Modeling of Total Column Ozone: Unraveling Equatorial Variability over Ethiopia Using Satellite Data and Multisource Covariates

TL;DR

This study employs a hierarchical Bayesian model with satellite data and environmental covariates to analyze and predict total column ozone variability over Ethiopia, revealing regional patterns and key influencing factors.

Contribution

It introduces a novel Bayesian hierarchical modeling approach using INLA and SPDE for spatiotemporal ozone analysis in an equatorial region, integrating multisource covariates.

Findings

High predictive accuracy with correlation coefficients above 0.9.

Identified key environmental factors affecting TCO, such as solar radiation and stratospheric temperature.

Revealed regional clusters and seasonal peaks in ozone levels.

Abstract

Understanding the spatiotemporal dynamics of total column ozone (TCO) is critical for monitoring ultraviolet (UV) exposure and ozone trends, particularly in equatorial regions where variability remains underexplored. This study investigates monthly TCO over Ethiopia (2012-2022) using a Bayesian hierarchical model implemented via Integrated Nested Laplace Approximation (INLA). The model incorporates nine environmental covariates, capturing meteorological, stratospheric, and topographic influences alongside spatiotemporal random effects. Spatial dependence is modeled using the Stochastic Partial Differential Equation (SPDE) approach, while temporal autocorrelation is handled through an autoregressive structure. The model shows strong predictive accuracy, with correlation coefficients of 0.94 (training) and 0.91 (validation), and RMSE values of 3.91 DU and 4.45 DU, respectively. Solar radiation, stratospheric temperature, and the Quasi-Biennial Oscillation are positively associated with TCO, whereas surface temperature, precipitation, humidity, water vapor, and altitude exhibit negative associations. Random effects highlight persistent regional clusters and seasonal peaks during summer. These findings provide new insights into regional ozone behavior over complex equatorial terrains, contributing to the understanding of the equatorial ozone paradox. The approach demonstrates the utility of combining satellite observations with environmental data in data-scarce regions, supporting improved UV risk monitoring and climate-informed policy planning.