Drought Reconstruction in the Qilian Mountains over the Last Two Centuries and Its Implications for Large-Scale Moisture Patterns

We present a composite tree-ring chronology from two sites of Qilian Juniper (Sabina przewalskii) in the northwestern Qilian Mountains (QM), Northwestern China. Precipitation in June was found to be the main limiting factor for tree-growth. The tree rings are also significantly and positively correlated with June precipitation over large areas of the northern Tibetan Plateau (TP). The authors thus consider that the tree-ring based drought reconstruction from 1803--2006 is representative of a large area drought history. During the reconstruction period, persistent and severe dry epochs occurred in the 1820s--1830s, 1870s--1880s, 1920s, and 1950s--1960s, and persistent wet periods were found from 1803--1810s, 1890s--1920s, and 1970s--1980s. The severe dry and wet periods are similar to those found over the northeastern TP, indicating the potential linkages of the drought regimes between them. Comparison with global SST indicates that the drought variability is closely related to the tropical Pacific and Arctic Ocean SSTs, suggesting the connection of regional moisture variations to the Asian monsoon and westerly belt circulations, respectively.