أنماط التوافق والتباين في تصنيف المواسم المطرية في العراق :دراسة مقارنة بين محطات الموصل وبغداد والبصرة للمدة 2024-1981

Abstract

The study aimed to investigate the regional variability of wet, normal, and dry rainfall seasons across northern, central, and southern Iraq by comparing the same rainfall season at the Mosul, Baghdad, and Basra stations over 43 consecutive seasons from 1981/1982 to 2023/2024. The study was based on seasonal rainfall totals for the period extending from October to May. Basic statistical indicators were calculated, and the standardized Z-score was then used to determine the relative position of each season with respect to the mean of each station and to classify it as wet, normal, or dry. The results showed that Mosul recorded the highest mean rainfall, reaching 349.3 mm, whereas Baghdad exhibited the greatest relative variability, with a coefficient of variation of 53.0%. The number of dry seasons reached 11 in Mosul, 15 in Baghdad, and 14 in Basra, compared with 10 wet seasons in Mosul and 12 wet seasons in each of Baghdad and Basra. Full concordance among the three stations occurred in 11 seasons (25.6%), while partial concordance was the dominant pattern, occurring in 29 seasons (67.4%). Complete divergence was limited to only three seasons (7.0%). Full concordance under dry conditions was also more frequent than full concordance under wet conditions, and the highest concordance rate was recorded between Mosul and Baghdad at 55.8%. The results demonstrate that the north–south rainfall gradient does not necessarily imply that the same rainfall season has an identical classification across the three regions. Rather, wetness and dryness in this study represent the relative position of each season within the climatic conditions of each station, highlighting the importance of direct regional comparison rather than relying solely on absolute rainfall amounts.