Spatiotemporal variations in precipitation extremes based on CMIP6 models and Shared Socioeconomic Pathway (SSP) scenarios over MENA.

Studying changes in precipitation extremes are important due to the possible increase in heavy rainfall, drought, and the occurrence of summer storms. Therefore, in this study, the trend of variations in precipitation extremes in the Middle East and North Africa (MENA) in the historical period (1985–2014) and the future period (2021–2050) was investigated. For this purpose, five precipitation extremes indices, including R10mm, R20mm, R95p, R99p, and PRCPTOT, and modified Man–Kendall trend test were used to examine the changes. To project changes in the future period, the multi-model mean of 12 GCMs from CMIP6 under three Shared Socioeconomic Pathway (SSP) scenarios including SSP1-2.6, SSP3-7.0, and SSP5-8.5 was utilized. The spatial distribution of the trend of changes in precipitation limits in the historical period showed that by moving from north to south and from west to east of the MENA region, all the studied indices have an increasing trend, so that the highest rate of decline is related to the countries of North Africa and also the PRCPTOT index and in Algeria, with a modified Man–Kendall coefficient of − 2.9. The highest increasing trend of the studied indices is related to the Middle East countries, especially countries such as Iran, Saudi Arabia, and Iraq with a modified Man–Kendall coefficient between 1.1 and 2.4, depending on the various indices. The distribution of variation trend in the future period also showed that the trends are similar to the historical period, with the difference that the downward trends in the studied indices are adjusted and the upward trends, especially based on the SSP5-8.5 scenario, would be intensified. Thus, the annual total precipitation on wet days (PRCPTOT) decreased and the annual count of days with 10- and 20-mm precipitation (R10mm and R20mm) as well as annual total PRCP with 95th and 99th percentiles (R95p and R99p) increased, with the largest increase in the Middle East and East of the MENA region; which indicates that despite the decrease in precipitation amount, the precipitation extremes and their intensities will increase. [ABSTRACT FROM AUTHOR]