Document Type : Research Paper
Authors
1
Professor of Climatology, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran.
2
Ph.D. of Climatology, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
10.22034/gp.2025.66933.3393
Abstract
Objective: This study was conducted to forecast precipitation at 5 synoptic meteorological stations located in the Caspian region of Iran in the next three decades.
Research Method: Data from three AOGCM models (INM-CM5-0, CMCC-CM2-SR5, BCC-CSM2-MR) from the CMIP6 series of models were used under two scenarios SSP2-4.5 (moderate) and SSP5-8.5 (pessimistic). The observation period was 1985-2014 and the future period was 2030-2059. The raw precipitation output was downscaled by CMHyd software. To reduce uncertainty with the weighted averaging method (based on rank), the ensemble model was calculated.
Resultss: The results showed that the generated ensemble model has better performance than the best single model of each station. In January, March, May, June, July and August, the average amount of precipitation changes in the average and pessimistic scenarios will be decreasing compared to the base period. In February, the average amount of precipitation changes in the moderate and pessimistic scenarios will be increasing compared to the observation period. In April, the average amount of precipitation changes in the two scenarios will be increasing compared to the base period in the moderate scenario and unchanged in the pessimistic scenario. Based on the uncertainty diagram drawn for the Rasht synoptic station under the two scenarios SSP245 and SSP585, in both scenarios, the amount of uncertainty has increased with distance from the observation period, and the increase in the uncertainty range has intensified from the 2040s onwards.
Conclusion: The results showed that the maximum change in monthly precipitation decrease in the future period compared to the previous period will occur in June with a value of 35%. Except for February, in all months, the amount of precipitation changes in the future period compared to the past is greater in the average scenario than in the pessimistic scenario.
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