Potential changes in the number of wet days and its effect on future intense and annual precipitation in northern Oman

The changes in the number of wet days (NWD) in Oman projected by climate models was analyzed, focusing mostly on variation of precipitation intensity and its effect on total annual precipitation (PTOT) in the future. The daily precipitation records of 49 gage stations were divided into five regions. Of the five general circulation models studied, two of them were selected based on their performance to simulate local-scale precipitation characteristics. All regions studied, except the interior desert region of the country, could experience fewer wet days in the future, with the most significant decreases estimated in southern Oman. The contribution from the cold frontal troughs to the PTOT in the northeast coastal region would decrease from 85% in the 1985-2004 period to 79% during the 2040-2059 period and further decrease to 77% during the 2080-2099 period. In contrast, results depict enhanced tropical cyclone activities in the northeast coastal region during the post-monsoon period. Despite the decreases in the NWD, PTOT in all regions would increase by 6-29% and 35-67% during the 2040-2059 and 2080-2099 periods, respectively. These results, therefore, show that increases in precipitation intensity dominate the changes in PTOT.