The Impact of Climate Change on the Duration of Periods of Southwest Asian Sea Depressions (Caspian and Black Seas) Over Iraq

Abstract

This study aims to analyze the impact of climate change on the number of days during which the Southwest Asian maritime depressions originating over the Black Sea and the Caspian Sea persist over Iraq. The analysis covers the temporal and spatial variability across three climatic cycles (1960–1971, 1990–2001, and 2010–2021). The research is based on 1000 hPa pressure-level data obtained from the National Oceanic and Atmospheric Administration (NOAA) for the 12 UTC daily observations (z12), along with synoptic weather charts available at http://www.esrl.noaa.gov/psd/data/composites. These tools were used to identify the presence and pathways of the depressions over the study stations (Mosul, Baghdad, and Basra). Linear trend analysis was then applied to determine the directional change in the duration of these systems throughout the study period.

       The results reveal a clear and consistent decline in the monthly and seasonal persistence of the Southwest Asian maritime depressions (Caspian–Black Sea systems) over Iraq during all their cool and mild activity months, extending from October to May. All stations exhibited negative trends, with the most pronounced decreases occurring in December, February, and March, particularly in Mosul, where the trend values reached –1.45, –1.35, and –1.75 days, respectively. Baghdad and Basra recorded similar negative patterns, though with lower magnitudes. The findings also show a complete absence of these depressions during the summer months (June, July, August), as well as a gradual decline during the spring season, especially in May, where the trend reached –0.4 days in Mosul, –0.25 days in Baghdad, and –0.2 days in Basra. At the seasonal level, the overall trend confirmed a substantial reduction, amounting to –8.95 days in Mosul, –5.5 days in Baghdad, and –4.7 days in Basra.

       These results indicate that Iraq is increasingly influenced by long-term climatic changes that have weakened the western depressions extending from the Caspian and Black Seas and shifted their tracks further north and east. This shift, combined with the growing dominance of warmer and drier air masses, has led to reduced wet periods, heightened aridity, and altered atmospheric circulation patterns over Iraq.