Projection of Iran’s precipitation during 2026-2075 by dynamical downscaling by RegCM4.7 under SSP scenarios

Articles in Press

Document Type : Original Article

Authors

1 Climate Research Institute

2 International Centre for Theoretical Physics

3 Senior researcher, Climate Research Institute, ASMERC/CRI, Mashahd

4 Senior researcher, Climate Research Institute, CRI/ASMERC, Mashahd

10.22125/agmj.2023.405388.1155

Abstract

Precipitation is the most important source of water supply for the agricultural sector, which is unevenly distributed across the country based on the long-term average. In this research, the MPI-ESM1.2-HR Earth System Model boundary condition data has been used for dynamically downscaling by RegCM4.7 regional climate model to project the country's average precipitation in the future period of 2026-2075 based on the SSP scenarios. Dynamical downscaling was performed according to SSP2-4.5 and SSP5-8.5 Shared Socio-economic Pathway scenarios from the primary horizontal resolution of 100×100 to 30×30 km. Precipitation projected by the regional climate model was bias corrected using the Linear Scaling (LS) method. In bias correctoion process, CRU gridded observation data and dynamically downscaled precipitation values in the historical period of 2000-2014 were used.

The results showed that the annual precipitation in the southern third of the country will be increased by 7 to 15% in all future periods and SSP scenarios, when comparing to the mean observation period. However, in the northern and central third of the country, both increasing and decreasing changes in precipitation (between -2% and +7%) were projected. In the spring and summer seasons, the precipitation is mainly increasing, with the largest increase in the spring in the southern regions and in the summer in the south and east of the country. On the other hand, in the western regions of the country, the precipitation is projected to decrease. In the autumn season, the country's precipitation is decreasing (increasing) based on SSP2-4.5 (SSP5-8.5). In the winter season, in all model-scenarios, the direction of precipitation change is increasing in the southwest of the country, decreasing in the west, and in other areas within the range of normal fluctuations.

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Journal of Agricultural Meteorology

Articles in Press, Accepted Manuscript
Available Online from 02 September 2023

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