Hierarchical Bayesian Extreme Value Modeling of Heatwave Intensities: Application to ERA5-Land in a Semi-Arid Region

Section: Articles
Issue
Vol. 20 No. 1 (2026): Vol. 20 No. 1 (2026): Volume 20 Issue 1
Pages
75-85

Keywords:

Extreme Temperature, Non-stationary GEV, Hierarchical Bayesian Modeling, ; Spatial Extremes, Climate Risk Assessment

Abstract

     In arid and semi-arid areas, especially in Iraq, extreme heat has become one of the most significant impacts of climate change, as the long duration of summer heat is becoming a serious threat to human health, water supply and infrastructure. This paper explores the issue of summer extreme temperatures in Iraq based on ERA5-Land daily maximum temperature data of 1980-2024. Descriptive heatwave indicators were then computed after which annual summer maxima were modeled in a Bayesian non-stationary generalized extreme value (GEV) framework in three climatic regions: North, Central, and South Iraq. A linear time effect in the location parameter was used to introduce non-stationarity, whilst the scale and shape parameters were fixed to maintain inferential stability because of the small number of annual maxima to use in each region. The results reveal a clear north–south gradient in baseline extreme heat intensity and a statistically credible warming trend of approximately  per decade. Return-level analysis further indicates that 20-year and 50-year extreme temperature levels increased by about  between the early period (1980–1999) and the recent period (2000–2024), with the most severe extremes concentrated in southern Iraq. These findings provide probabilistic evidence that extreme heat risk in Iraq is intensifying under a non-stationary climate and demonstrate the value of Bayesian non-stationary extreme-value modeling for regional climate-risk assessment.

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Author

Saifuldeen Alrefaee

Department of Operations Research and Intelligent Technologies, College of Computer Science and Mathematics, University of Mosul, Mosul, Iraq

Identifiers

DOI: 10.33899/rjcsm.v20i1.60668

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Hierarchical Bayesian Extreme Value Modeling of Heatwave Intensities: Application to ERA5-Land in a Semi-Arid Region. (2026). AL-Rafidain Journal of Computer Sciences and Mathematics, 20(1), 75-85. https://doi.org/10.33899/rjcsm.v20i1.60668
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How to Cite

Hierarchical Bayesian Extreme Value Modeling of Heatwave Intensities: Application to ERA5-Land in a Semi-Arid Region. (2026). AL-Rafidain Journal of Computer Sciences and Mathematics, 20(1), 75-85. https://doi.org/10.33899/rjcsm.v20i1.60668