A tree-ring-based drought reconstruction from 1466 to 2013 CE for the Aksu area, western China

摘要

The Aksu area is located in western Xinjiang, China, where an oasis is the main space for human production and life in this region. The stability of the oasis is crucial for societal and economic development and can be severely impacted by continued drought. The Palmer Drought Severity Index (PDSI), a widely applied index for dryness, has been reconstructed in many areas by tree rings. Here we develop a new regional long tree-ring-width chronology of Schrenk's spruce (Picea schrenkiana Fisch. et Mey.) from the Aksu area. Based on the regional PDSI from the previous September to current March (PDSIp9-c3), regional drought variability is reconstructed in the past 548 years (1466-2013 CE). The regional PDSI reconstruction captures distinct wet and dry periods and also some low-frequency climate signals. A decadal analysis reveals 12 wet and 12 dry periods in the past 548 years, of which 1514-1560 CE was the longest dry period. The prominent mega-drought during the mid-sixteenth century is particularly pronounced. The PDSI in the Aksu area records a notable sudden onset and long period of wet conditions from the 1980s until the present day. Mechanism analysis indicates that the regional drought has been mainly affected by the North Atlantic Oscillation (NAO) over the last centuries through an anti-phase relationship.