Simulated precipitation changes in Central Asia since the Last Glacial Maximum

摘要

The availability of freshwater has been and remains a crucial concern in westerlies-dominated arid Central Asia. Understanding precipitation changes in this area and the underlying mechanisms, therefore, is of great importance. This study explores precipitation changes in Central Asia (35 degrees-50 degrees N and 50 degrees-70 degrees E) since the Last Glacial Maximum (LGM) and their control factors using results from the "Simulation of Transient Climate Evolution over the last 21,000 years". Transient simulations reveal that a wet climate occurred during the LGM, the Belling-Allered warm period, and the middle Holocene, and a dry climate occurred during Heinrich event 1, the Younger Dryas, and the early Holocene in this area. Model results are in good agreement with proxy records since the last deglaciation. These changes were mainly controlled by Earth's orbital parameters, meltwater discharges into the oceans and continental ice sheets. The contribution of GHG concentrations to precipitation changes was minor. External forcing factors influenced the precipitation mainly through affecting the water vapor input from the North Atlantic and Mediterranean Sea, and vertical motions of the atmosphere over Central Asia. The North Atlantic Oscillation was an important atmospheric bridge connecting the external forcings to precipitation changes in Central Asia. There were complex relationships between precipitation changes in Central Asia and East Asia since the LGM due to the differences of the dominating factors.