Reconstructed droughts for the northeastern Tibetan Plateau since AD 1411 and its linkages to the Pacific, Indian and Atlantic Oceans

Based on the tree rings of Qilian juniper (Juniperus przewalskii), this paper presents a Palmer Drought Severity Index (PDSI) reconstruction (r = 0.578, p < 0.01) since AD 1411 for the northeastern Tibetan Plateau (TP). Regional extreme dry years (<2SD) were found in 1451, 1455, 1480, 1488, 1490, 1591, 1649, 1770, 1776, 1824, 1831, 1879, 1922, 1927 and 1992, while extreme wet years (≥2SD) were not observed. Persistent decadal dry intervals were observed in the 1450s, 1480s, 1510s, 1580s–90s, 1680s–1720s, 1820s–40s, 1920s–30s and after 1990s, and decadal wet intervals in the 1410s, 1500s, 1540s–50s, 1610s–70s, 1750s–60s, 1790s–1800s, 1880s–1910s, 1960s–80s. Regional droughts evident in the reconstruction appear to be relatively consistent with the drought history of the entire arid northeastern TP to the north indicated by previous studies. Spectral peaks of 2.1–5.9 years may be indicative of ENSO and IOD activity, as also suggested by negative correlations with SSTs in the eastern equatorial and southeastern Pacific Ocean and the northern Indian Ocean. Significant multi-decadal spectral peaks of 31.1–36.6 years and 41–53.8 years were identified and indicated that the decadal-scale variability may be linked to SST variations in the northern Pacific and Atlantic Oceans.