Document Type : Research Article
Authors
1
Department of Physical Geography, Faculty of Geography and environmental planning, University of Sistan and Baluchestan, Zahedan, Iran
2
Associate Professor, Department of Physical Geography, Faculty of Geography and Environmental Planning, University of Sistan and Baluchestan, Zahedan, Iran
3
Assistant Professor, Department of Physical Geography, Faculty of Geography and Environmental Planning, University of Sistan and Baluchestan, Zahedan, Iran
10.22059/jhsci.2024.378547.829
Abstract
Extreme precipitation is one of the most important hazardous weather phenomena in southeastern Iran, leading to substantial economic and social impacts annually. This study aims to examine the temporal and spatial variations in extreme precipitation in the region and its correlation with Sudan low-pressure systems. To achieve this goal, data from the Aphrodite and CHIRPS for precipitation with spatial resolution (0.25° by 0.25°) and SLP (ER5) data with spatial resolution (0.75° by 0.75°) were used over a 40-year period (1979 to 2018). Extreme precipitation events were identified by examining the 90th and 95th percentiles. To locate low-pressure centers, criteria included having the lowest pressure relative to eight surrounding points, a pressure difference of 0.8 to 3.8 hPa between these points and the central pressure, which needed to be below 1008 hPa. Temporal and spatial variations were assessed using a modified Mann-Kendall nonparametric method along with Sen's slope estimator. The results of the first part showed that extreme precipitation had different spatial distributions across the region, with approximately 49% and 30% of network points showing significant positive trends according to the 90th and 95th percentiles, respectively. The remaining points exhibited no discernible trend, particularly in the central part where weather stations may be lacking. The findings from the synoptic analysis indicate that the alterations in precipitation boundaries in Sudan can be explained by the variations in the activity of low-pressure centers, so that in the second period, The Sudan low pressure had a relatively higher frequency. This means that the intensity of heavy rains is associated with the increase of extreme low pressure events in Sudan.
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