Spatio-temporal changes of atmospheric rivers in the Middle East and North Africa region

Atmospheric rivers (ARs) are narrow pathways of atmospheric humidity which have a critical role in the global water cycle and can affect natural phenomena such as severe storms and floods. In this article, their temporal and spatial changes in the MENA (Middle East and North Africa) region have been investigated during a period of 30 years (1984-2013). After extracting the days with ARs, their frequency and sources were identified. In order to study the formation and moisture feeding mechanism of the ARs, the jet stream and atmospheric stream maps were produced, and their sources and movement paths were identified. The results showed that each year, about 13 ARs were observed and most of them occurred in the fall and winter seasons. The major reason for the formation of ARs is jet streams which, in all selected cases, were located about 100-150hPa above the ARs. Most ARs originated over the North Atlantic Ocean and entered Africa from Mauritania and Senegal and after passing Egypt, Saudi Arabia and Iran entered Afghanistan and Pakistan. The Red Sea is a major moisture source which feeds ARs on their path. The results showed that the ARs in the MENA region experience convergence over this region which causes these events to narrow. A large number of the countries that studied is desert, the findings can be utilized in understanding the ways ARs can be useful and shortage of water resources in the region can be compensated.