The Impact of Climate Change on the Duration of the 5700-Meter thickness line Level over Iraq and Its Relationship to Changes in the Duration of Surface Pressure Systems During the Rainy Season (1948/1949–2016/2017) A Study in Synoptic Climate Change

Abstract

This research aims to analyze the impact of climate change on the duration of the 5700 m thickness line، a type of thickness line between the 1000-500 hectopascal levels، which represents the boundary of tropical air masses over Iraq for the period 1948/1949-2016/2017، spanning 69 rainy seasons. The results of the analysis of the change in the duration of the tropical thickness line showed a general trend towards an increase in the number of days it remained over Iraq، specifically over the northern region، where the percentage change in the studied climatic cycles reached 17.35%، over the central region 10.48%، and over the southern region 8.45% This variation is attributed to the geographical location factor. This variation shows that the northern region was greatly affected by the increased duration of the tropical high-pressure system، indicating the strength of these influences and their reach to the southern edges of the northern temperate latitudes as a result of climate change. It also showed that the changes in surface pressure systems associated with the 5700 m high-pressure system have varying trends for the same duration، as the duration of the Sudanese and Mediterranean low-pressure systems tended to decrease during the rainy season months Negative change rates are accompanied by increased durations of the Indian monsoon low، merged lows، and subtropical high، which have contributed to increased durations of tropical storms over Iraq. This is due to the increased thickness of the atmospheric layers associated with these systems، also resulting from higher temperatures due to climate change، particularly the Indian monsoon low، whose duration has increased significantly at the beginning and end of the rainy season The results of the specialist analysis showed significant inverse correlations between the weakening of Sudanese and Mediterranean low-pressure systems and the increase in the tropical high-pressure system.