1 531-year non-growth season precipitation reconstruction in the 1 southeastern Tibetan Plateau

Trees record climatic conditions during their growth, and tree-rings serve as a proxy to reveal the features of the 13 historical climate of a region. In this study, we collected tree-ring cores of forest hemlock (Tsuga forrestii) from the 14 northwestern Yunnan area of the southeastern Tibetan Plateau (SETP), and created a residual tree-ring width (TRW) 15 chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growth 16 season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor 17 on the radial tree growth of forest hemlock in this region. In addition, the influence of NGS precipitation on radial tree growth 18 was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning 19 from A.D. 1475–2005. The reconstruction accounted for 28.5% of the actual variance during the common period 1956–2005, 20 and the leave-one-out verification parameters indicated the reliability of the reconstruction. Based on the reconstruction, NGS 21 was extremely dry during the years A.D. 1475, 1656, 1670, 1694, 1703, 1736, 1897, 1907, 1943, 1969, 1982, and 1999. In 22 contrast, the NGS was extremely wet during the years A.D. 1491, 1536, 1558, 1627, 1638, 1654, 1832, 1834–1835, and 1992. 23 Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions 24 from surrounding regions indicated the reliability of the reconstruction. A comparison of the reconstruction with Climate 25 Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of 26 a large region in the SETP. 27