Tree-ring based drought reconstruction for the central Tien Shan area in northwest China

A robust ring-width chronology developed from two sites of Picea schrenkiana in the central Tien Shan area of northwest China was employed to study regional drought variability. Our analyses demonstrate both temperature and precipitation have significant effects on tree growth, thus both should be considered for climate reconstruction. Regional drought history (1675-2002 A. D.) was therefore reconstructed by calibrating with the Palmer Drought Severity Index (PDSI). Our reconstruction not only captured well those extreme drought events recorded in local historical archives, but also revealed the long-term pattern of drought variability, especially the trend of increasing moisture during the 20th century. Multi-taper method spectral analysis indicates the existence of some low- and high-frequency cycles (146-171, 11.5, 10.6, 9.7, 6.1, 3.9, 3.4, 3.2, 2.4 and 2.1 yr). Overall, our study indicates the feasibility of combining tree-rings and the PDSI to reconstruct large-scale drought patterns over this area.