Sensitivity Of Water Balance In The Qaidam Basin To The Mid-Pliocene Climate

The Qaidam Basin (QB) in the northeastern Tibetan Plateau held a megalake system during the Pliocene. Today, the lower elevations in the basin are hyperarid. To understand to what extent the climate plays a role in the maintenance of the megalake system during the Pliocene, we applied the Weather Research and Forecasting model for dynamical downscaling of ECHAM5 global climate simulations for the present day and the mid-Pliocene. When imposing the mid-Pliocene climate on the QB with its modern land surface settings, the annual water balance (Delta S), that is, the change in terrestrial water storage within the QB, increases. This positive imbalance of Delta S induced solely by the changes in the large-scale climate state would lead to a readjustment of lake extent, until a new equilibrium state is reached, where loss due to evaporation over lake areas compensates for the input by runoff and precipitation. Atmospheric water transport (AWT) analysis at each border of the QB reveals that this imbalance of Delta S is caused by stronger moisture influx across the western border in winter, spring, and autumn and weaker moisture out-flux across the eastern border in summer. These changes in AWT are associated with the strengthening of the midlatitude westerlies in all seasons, except for summer, and the intensification of the East Asian Summer Monsoon. Given that the mid-Pliocene climate is an analog to the projected warm climate of the near future, our study contributes to a better understanding of climate change impacts in central Asia.