Projection changes of extreme precipitation with different return periods in Iran based on the ensemble approach of 10 CMIP6 models in the near future

Document Type : Research Article


1 Atmospheric Science and Meteorological Research Center, Tehran, Iran

2 bResearch Institute of Meteorology and Atmospheric Science, Tehran, Iran

3 Ferdowsi university



In the current study, the changes in the amount of extreme precipitation with different return periods in the period of 2026-2050 were studied with the weighted combination of 10 CMIP6 models in different scenarios. According to the spatial and temporal ranking of historical simulation performance of 10 CMIP6 models in Iran, the weights for each model were obtained. Subsequently, a rank-based weighting method was employed to project the levels of extreme precipitation in the study area. In the continuation of the extreme precipitations in the best statistical distribution according to the data for each of the stations, in 84% of the stations Log-Pearson Type 3 distribution was selected with chi-square test, in the historical period (1990- 2014) and the future was calculated in all three scenarios and different return periods. Upon comparing the results of extreme precipitation between the future and historical periods, it became evident that the percentage of change in projected extreme precipitation was notably higher in the SSP2-4.5 scenario compared to the other two scenarios. Also, towards the longer return period, the percentage increase in the amount of projected extreme precipitation increases and the area of its occurrence also expands. The greatest increase in the amount of projected extreme precipitation (more than 25%) in SSP1-2.6 scenario is in Gorgan, Babolsar, Bojnord, Arak, Isfahan and Zahedan stations, in SSP2-4.5 scenario in Gorgan, Sanandaj, Hamedan, Arak, Kashan, Isfahan, Shiraz, Fasa, Minab, Bushehr, Bandar Abbas, Bandar Lange, Abu Musi stations, and in SSP5-8.5 scenario, it was observed in Bojnord, Birjand, Arak, Kashan and Semnan stations. An increase in the amount of extreme precipitation was observed in Arak station in all three scenarios (about 70% in SSP1-2.6 and SSP2-4.5 scenarios, about 50% in SSP5-8.5 scenario in the 200-year return period) in Arak station.


Main Subjects


Articles in Press, Accepted Manuscript
Available Online from 11 May 2024
  • Receive Date: 20 January 2024
  • Revise Date: 06 April 2024
  • Accept Date: 11 May 2024