Al‐Nassar et al. (2026) On the Temporal Variability of Precipitation in Iraq: Arid‐Wet Years and Extreme Events

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: International Journal of Climatology
• Year: 2026
• Date: 2026-04-06
• Authors: Ali Raheem Al‐Nassar, Josep Lluís Pelegrí, P. Masciangioli
• DOI: 10.1002/joc.70350

Research Groups

Not explicitly stated in the abstract.

Short Summary

This study analyzes long-term precipitation variability in Iraq, distinguishing between arid and wet years and characterizing extreme events, revealing that the Indian Ocean Dipole (IOD) significantly influences interannual variability by modulating autumn-winter moisture arrival.

Objective

• To examine the variability of precipitation in Iraq, focusing on the differences between arid and wet years and characterizing the intensity and synoptic drivers of extreme precipitation events.

Study Configuration

• Spatial Scale: Iraq (country-wide weighted mean, specific stations: Mosul, Rutba, Baghdad, Basrah).
• Temporal Scale:
  • Monthly precipitation records: 84 years (1938–2023, excluding 2003 and 2004).
  • Daily precipitation records (Baghdad): 19 years (2005–2023).
  • Extreme value analysis for return periods up to 100 years.

Methodology and Data

• Models used:
  • Extreme value analysis (Peak Over Threshold (POT), Block Maxima (BM))
  • Probability Density Function (PDF) analysis
  • Correlation analysis
• Data sources:
  • Long-term station precipitation records (monthly from four stations, daily from Baghdad).
  • Reanalysis weather data.
  • Indian Ocean Dipole (IOD) index.

Main Results

• Annual precipitation (mean ± standard deviation) values were: Mosul (367 ± 140 mm), Rutba (107 ± 59 mm), Baghdad (138 ± 65 mm), and Basrah (136 ± 60 mm), with a weighted mean for Iraq of 182 ± 57 mm.
• Precipitation time series exhibit strong seasonality (maximum in winter, negligible in summer) and interannual variations spanning an order of magnitude.
• Arid and wet years, defined by annual precipitation below the 25th and above the 75th percentiles respectively, show substantial differences in their seasonal cycles.
• Monthly precipitation is significantly correlated with the Indian Ocean Dipole (IOD) index, indicating that IOD enhances autumn-winter precipitation by influencing moisture transport from the Red Sea, Arabian Sea, and Persian Gulf.
• 36 extreme precipitation events were identified in Baghdad (2005–2023), contributing 1452 mm (56%) of the total precipitation for that period, and were classified as jet streak, cut-off low, upper-air trough, or Rex block events.
• The frequency of extreme events does not increase during wet years, suggesting that seasonal IOD conditioning is the primary driver of arid-wet year variability.
• Extreme value analysis for daily data showed POT provided narrower high-confidence bands compared to BM, while for monthly data, both methods yielded similar mean and high-confidence values for return periods up to 100 years.

Contributions

• Provides a comprehensive, long-term analysis of precipitation variability across Iraq, including quantitative characterization of arid/wet years and extreme events.
• Establishes a significant correlation between monthly precipitation in Iraq and the Indian Ocean Dipole (IOD), identifying a key climatic driver for interannual variability.
• Classifies and quantifies the contribution of specific synoptic weather patterns (e.g., jet streak, cut-off low) to extreme precipitation events in the region.
• Offers robust extreme value analysis for both daily and monthly precipitation, providing critical return values for hydrological planning and risk assessment.

Funding

Not explicitly stated in the abstract.

Citation

@article{AlNassar2026Temporal,
  author = {Al‐Nassar, Ali Raheem and Pelegrí, Josep Lluís and Masciangioli, P.},
  title = {On the Temporal Variability of Precipitation in Iraq: Arid‐Wet Years and Extreme Events},
  journal = {International Journal of Climatology},
  year = {2026},
  doi = {10.1002/joc.70350},
  url = {https://doi.org/10.1002/joc.70350}
}