فهرست نشریات علمی دسترسی آزاد ایران

Mediterranean low-pressure systems are among the most important rain-producing systems for Middle east and Iran during the cold half of the year. In this study, nearly 2,400 weather-maps at a level of 1000 HPA were downloaded from the NOAA website. The identification of the stages of these low-pressure systems, including their formation, strengthening, and tracking, was carried out over two decades and in four representative months of the seasons, including November, February, May, and August, respectively. The aforementioned identification was divided into two categories: low-pressures were towards Iran (LTI) and low pressures were towards other lands (LTO). Initial results showed that 418 low-pressure systems formed and moved over the Mediterranean Sea between 2003 and 2022. Of the 418 recovered tracks, 88 ones were LTIs and 330 ones were LTOs. Meanwhile, the 21% share of LTIs has been decreasing at a gentle rate over the last two decades. Marking the tracks on the base maps at three scales of months, years, and decades showed that these systems have diverged towards the east on three pathways, from the western and central northern Mediterranean areas. Pathway No. (1) passed through the southeastern part of the Hijaz in the first decade, but in the second decade it turned northward and crossed the southern provinces of Iran. Pathway No. (2) passed through the central lands of Iran in the first decade, and in the second decade, it left Iran with a significant northward turn, crossing the middle of the Caspian Sea towards the plains of Turan (Central Asia). Pathway No. (3) passed over the Black Sea at the highest latitudes during the first decade, but in the second decade, it went out of the map frame north of this sea. Overall, the decadal patterns showed that most of the LTIs and LTOs tracks were extended to higher latitudes during the years 2013 to 2022 (second decade) compared to the years 2003 to 2012 (first decade). Therefore, given the persistent and mild nature of precipitation resulting from Mediterranean systems, it is believed that as more southern systems such as Sudanese low-pressure systems replace them, it will become more difficult for planners to store and manage Iran's water resources.