Projected Changes in Precipitation Extremes of Mashhad During the Twenty First Century

In assessing the potential impacts of climate change on different sections including water, agriculture, and urban drainage management, projection of changes in climate extremes as the results of climate change and global warming are essential. To have an outlook on future projections of climate extremes particularly precipitation, the outputs derived from three coupled general circulation models (HadCM3, NCCCSM, and CGCM3T47) contributing to the Fourth Assessment Report of the IPCCAR4, have been downscaled for Mashhad station under A1B emission scenarios by LARS- WG during three period 2011-2030, 2046-2065 and 2080-2099. The extremes are described by seven indices based on precipitation including CDD, R10mm, R20mm, RX5day, SDII, R95T, and R99T. The results showed that heavy precipitation events for pentads increase the maximum five-day precipitation and their intensity in three sequential periods. In addition, a larger fraction of the total annual precipitation is projected to occur during heavy precipitation events, i.e. events that exceed the 95th and 99th percentile. Increases are found for these indices indicated the more frequent future occurrence of floods in the twenty first century.