Abstract
In this study, we have analyzed the spatial and temporal correlation between the North Atlantic Oscillation (NAO) and the climate in Iraq, with a focus on precipitation, temperature, and number of Mediterranean cyclones. It was found that the influence of the NAO varies per climate indicator. For example, the influence is greater on precipitation than on temperature. One conclusion of the study is that the mean annual precipitation in Iraq increases during a negative phase of the NAO and decreases during a positive phase. In addition, the correlation between NAO and precipitation is more pronounced in the south of the country than in the middle and northern regions.
Regarding the temporal correlation between NAO and precipitation, the influence of the NAO on Iraqi precipitation was found to be weak during the fall season, but to become more pronounced in the winter, culminating during the spring, and then vanishing in the summer.
It was also concluded that when the NAO is in a positive phase, the area featuring a desert climate (Bwha) expands in Iraq, while the area featuring other climates decreases. During these years, both the Mediterranean climate (Csa) and the steppe climate (Bsha) cover a smaller part of the country due to the limited amount of precipitation. The opposite occurs during a negative phase of the NAO.
Analysis of the number of Mediterranean cyclones that reach Iraq shows that there is no significant difference in the number of cyclones occurring during negative and positive phases of the NAO. However, there are differences in the strength of the cyclones.
This study represents a first step in analyzing the relation between the NAO and the Iraqi climate and hopes to lead to further research.
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Notes
Only three seasons are presented since summer season in Iraq is dry and no rain was recorded at the weather stations from June until end of September.
The precipitation season in Iraq starts in October and ends in May.
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Khidher, S.A., Pilesjö, P. The effect of the North Atlantic Oscillation on the Iraqi climate 1982–2000. Theor Appl Climatol 122, 771–782 (2015). https://doi.org/10.1007/s00704-014-1327-4
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DOI: https://doi.org/10.1007/s00704-014-1327-4