تكرار ومدة بقاء الحاجز الضغطي فوق العراق للمدة 1970_2024

Abstract

This research provides a detailed analysis of the frequency and duration of the pressure barrier over Iraq during the period (1970–2024), aiming to clarify its role in influencing the paths of weather systems, particularly Mediterranean depressions, which are the primary source of rainfall in the country. The study relied on daily data. Atmospheric pressure and analytical maps were used to identify all instances where the pressure barrier was clearly present, then its annual and seasonal frequency was calculated, along with its average duration and temporal distribution across decades. The results showed a marked fluctuation in the frequency of the pressure barrier between time periods. The study also showed that most pressure barriers have a gradual increase in frequency over recent decades, which has directly impacted the effectiveness of Mediterranean low-pressure systems when they enter Iraqi airspace. Furthermore, the study indicated that most pressure barriers are characterized by a short to medium duration. However, its impact is significant in altering the paths of low-pressure systems or delaying their arrival, leading to a decrease in rainfall amounts and irregularity in rainfall seasons, especially during the autumn and winter months upon which the agricultural cycle in Iraq depends. The results confirm that the increased frequency of the pressure barrier and the length of its duration are closely related. With increasingly arid conditions and more frequent periods of low rainfall, understanding the dynamics of this weather system within the context of accelerating climate change is crucial. These findings underscore Iraq's need for continuous monitoring of weather patterns and an assessment of their future impacts on water resources.