Impacts of the uplift of the Pamirs and northern Tibetan Plateau on the aridification of the Taklimakan and Thar deserts since the Miocene

Abstract

The impacts of topographic uplift in different areas of the Tibetan Plateau (TP) on the arid climate and dust cycle in the sandy areas on the north and south sides of the plateau are studied using a regional climate model (RCM) by comparing numerical experiments on the uplift of the Pamirs and the northern TP. Simulation results based on tectonic geological records can be used to explain the differences in drought evolution in different areas around the TP. The results show that: (1) The mechanical blocking effect caused by the uplift of the Pamirs has mainly intensified the aridification and desertification of the Taklimakan Desert since the Pliocene, and its uplift has blocked the water vapor channel in the west side of Tarim Basin, causing a 50% reduction in the annual precipitation (mainly winter precipitation) and a 10-30% increase in the atmospheric dust loading in the Taklimakan Deserts. (2) The uplift of the northern Tibetan Plateau mainly intensifies the aridification of the Thar Desert. The uplift of the northern TP controls the position and intensity of the subtropical high center at 700 hPa in the Thar Desert, causing a 50% reduction in summer and annual precipitation and increase in the atmospheric dust loading in the Thar Desert. (3) The aridification of the Gobi Desert and Loess Plateau since the Miocene is also related to the uplift of the northern TP. The uplifting suppresses the East Asian summer monsoon (EASM), causing a 30-50% reduction in summer precipitation in the Gobi Desert and Loess Plateau. Drought further causes a 10-20% increase in the dust loading in the above areas. (4) In view of the limited geological evidence of remarkable tectonic uplift in the northern TP and the Pamirs since the Miocene and Pliocene respectively and based on the current numerical simulation results, it is speculated that the formation of the Thar Desert should be earlier than the Taklimakan Desert.