The pressure systems responsible for seasonal and intermittent rainfall in Iraq

Abstract

The investigation aimed to explore the pressure systems accountable for the seasonal and sporadic precipitation in Iraq, as well as to pinpoint the specific periods of occurrence spanning from 2011 to 2022. This was achieved through the utilization of daily data obtained from eight climatic stations, coupled with the examination of meteorological and surface charts pertaining to pressure levels set at 1000, 850, and 500 millibars. The findings of the study unveiled the precise commencement of seasonal rainfall, predominantly concentrated between October and November across the majority of stations within the research area. On the other hand, the initiation of intermittent rainfall exhibited variability, encompassing the months of October, November, and December, with the most extended duration recorded at 59 days for the Rutbah station during the 2017-2018 season, and the shortest period of one day observed at stations such as Kirkuk, Rutbah, Nasiriyah, Diwaniyah, and Basra. Moreover, the maximum number of consecutive days experiencing seasonal rainfall at the Kirkuk station amounted to 9 days during the 2014-2015 season, while Mosul and Rutbah stations recorded the highest number of continuous days with intermittent rainfall, reaching 6 days in the 2013-2014 season. Conversely, the minimum duration of continuous seasonal and intermittent rainfall was found to be one day, emerging as the most prevalent timeframe throughout the duration of the research. In terms of cumulative seasonal precipitation, Mosul station registered the highest amount at 126.9 mm, whereas the lowest was documented at Al-Hay station with 17.7 mm. Conversely, for intermittent rainfall, Nasiriyah station showcased the highest total at 152.1 mm, while Kirkuk station displayed the lowest at 58.5 mm. Ultimately, the study deduced that the Sudanese depression played a substantial role in generating seasonal rainfall, attributing to 76% of the precipitation during the observation time at 00 GMT, and 79% during the observation time at 12 GMT, while accounting for 71% of intermittent rainfall during both observation periods at 00 and 12 GMT.