Document Type : Complete scientific research article
Authors
1
Water and Hydraulic Structures department, Faculty of Civil Engineering, Art and Architecture, Islamic Azad University Science and Research Branch, Tehran, Iran
2
Corresponding Author, Associate Prof., Dept. of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
3
Department of Soil Science, Faculty of Agriculture, University of Kurdistan
10.22069/ejsms.2025.22485.2153
Abstract
Background and Objectives: Climate change is a critical issue that experts in various fields have focused on. Given that climate change is a worldwide phenomenon, it affects more or less all countries, including Iran. Given the increasing challenges posed by climate change and the documented impacts in the Karaj and Qazvin regions from previous studies, this research aims to investigate climate change forecasting and its effects on minimum temperature, maximum temperature, precipitation, and sunshine hours. The study utilizes data from the CMIP6 report to analyze these parameters over two distinct time periods: the near future and the far future.
Materials and Methods: This research used daily data on minimum and maximum temperature, rainfall, and sunshine hours from the synoptic stations of Karaj, Taleghan (Karaj province), Qazvin, and Bagh Kausar (Qazvin province) from 1980 to 2015 as the base period data, obtained from the National Meteorological Organization's database. To investigate the impact of climate change on the selected parameters, the three best models (HadGEM3, AccESSESM1, and MRI-ESM) from the CMIP6 report were utilized. The LARS-WG statistical downscaling model was employed to assess the scenarios under the optimistic SSP1-2.6, moderate SSP2-4.5, and pessimistic SSP5-8.5 conditions for the future time periods (2030-2050) and (2050-2070), comparing the results to the base period (1980-2015). The evaluation of the LARS-WG model involved examining the error rate between observational and simulation data using NRMSE, MAE, RMSE, MSE, and R2 criteria.
Results: The results showed that minimum and maximum temperatures are expected to increase in most of the studied months and stations in the future periods. It is anticipated that there will be more warming, with the minimum temperature showing an increase of 2.25°C compared to the base period. The average maximum temperature is projected to increase by 2.25°C to 3.5°C under the SSP5-8.5 scenario and up to 2.3°C under the SSP2-4.5 scenario compared to the base period. The data also indicate an average increase of 2.2°C in the maximum temperature during the spring and autumn seasons, along with an average decrease of 66.66% in precipitation during the months of March, April, and May compared to the base period. Furthermore, the sunshine hours parameter is expected to increase in all months during the next two investigated periods.
Conclusion: The results obtained from the investigated parameters (minimum temperature, maximum temperature, precipitation, and sunshine hours) for the future periods showed an increasing trend in minimum temperature (Tmin) and sunshine hours (snhn) across all three models under the scenarios. However, the precipitation parameter (Rain) displayed a decreasing trend in most months, with a partial increase/decrease trend in some stations. Overall, the average total monthly rainfall in the (2030-2050) and (2050-2070) periods is projected to have a decreasing trend under all three scenarios. The findings of this research are in line with the expected changes in temperature, precipitation, and sunshine hours, reflecting the climate's anticipated transformations in the study region.
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