Probability of Recurrence of Heat and Cold Waves in the Climate of Iraq

The study aims to determine the likelihood of heat and cold waves recurring in the climate of Iraq due to their extreme importance. This was done by defining heat and cold waves, which are defined as relatively short periods of time characterized by a severe rise or fall in temperatures compared to normal climatic averages, lasting for several days, and resulting from changes in weather systems, air masses, and factors affecting their occurrence, such as fixed factors represented by the geographical and astronomical location, location in relation to water bodies, and topography, and moving (dynamic) factors represented by high and low pressure systems, air masses, and jet streams. The study methodology employed a descriptive-analytical approach to describe the phenomenon of heat and cold waves in Iraq and analyze their temporal and spatial distribution. The study aimed to determine the general trend and variation in heat and cold waves and calculate their frequencies for the period 1991-2023, divided into three minor climatic cycles: the first cycle (1991-2001), the second cycle (2002-2012), and the third cycle (2013-2023). This was achieved by studying nine meteorological stations across Iraq: Mosul, Khanaqin, Rutba, Baghdad, Najaf, Al-Hayy, Amarah, Nasiriyah, and Basra. The Mann-Kendall test was used to calculate the frequency of heat and cold waves. The study also aimed to determine the probability of recurrence of heat and cold waves using Poisson's equation. The study revealed both spatial and temporal variations in the recorded frequency of heat and cold waves throughout the study period. The total number of heat waves recorded during the study period was 876, while cold waves totaled 522. The second climate cycle (2002-2012) recorded the highest annual average frequency of heat waves at 361, representing the highest percentage of heat wave frequency in Iraq among the three climate cycles, at 41.2% of the total heat wave frequency during the study period. Conversely, the third climate cycle (2013-2023) recorded the highest annual average frequency of cold waves at 205, representing the highest percentage of cold wave frequency in Iraq among the three climate cycles, at 39.3% during the study period. The third climatic cycle (2013-2023) recorded the lowest frequency of heat waves, with 219 waves, representing 25% of the total frequency of heat waves in Iraq during the study period. Conversely, the first climatic cycle (1991-2001) recorded the lowest frequency of cold waves, with 145 waves, representing 27.8% of the total frequency of cold waves in Iraq during the study period. The study also confirmed that the main reason for the increased frequency of heat waves, characterized by high maximum temperatures at most stations in the study area (excluding Mosul and Rutba), is local environmental factors such as urban expansion, increased industrial activity, desertification, reduced vegetation cover, and decreased rainfall. Furthermore, the frequency of heat and cold waves varied across meteorological stations in Iraq. The Basra station recorded the highest annual frequency of heat waves, with 172 waves, constituting 19.63% of the total number of heat waves in Iraq. While the Amarah station recorded the lowest annual frequency of heat waves in Iraq, with 54 waves (6.2% of the total), the Mosul station recorded the highest annual frequency of cold waves, with 81 waves (15.5% of the total). The Basra station, on the other hand, recorded the lowest annual frequency of cold waves, with 42 waves (8.05% of the total). The study revealed that the observed changes in the frequency of heat and cold waves in Iraq across different climatic cycles are consistent with the increasing frequency of climatic phenomena recorded globally. This clearly indicates the impact of these changes on Iraq's climate, both in its fundamental climatic elements and in the associated weather phenomena. The most significant finding of the study is the clear temporal and spatial variation in the frequency of heat waves and the relatively low frequency of cold waves.