A 426-year drought history for Western Tian Shan, Central Asia, inferred from tree rings and linkages to the North Atlantic and Indo-West Pacific Oceans

We have reconstructed the Palmer Drought Severity Index (PDSI) from 1580 to 2005 for Western Tian Shan, Central Asia, using tree rings of Picea schrenkiana. The reconstruction explains 35% of the actual January-May PDSI variance during the common period 1925-2005. Split-sample validation supports our use of the reconstruction model based on the full period of reliable observational data (1925-2005). Spatial climate correlation analyses with gridded PDSI data revealed that our PDSI reconstruction represents a strong regional drought signal for Western Tian Shan. Dry periods occurred during ad 1614-1628, 1700-1722, 1758-1790, 1806-1833, 1873-1898, 1908-1936, 1943-1951, 1960-1966 and 1973-1988; while the periods of ad 1580-1613, 1629-1699, 1723-1757, 1791-1805, 1834-1872, 1899-1907, 1937-1942, 1952-1959, 1967-1972 and 1989-present were relatively wet. Our reconstruction agrees reasonably well with the dry and wet periods previously estimated from tree rings in Tian Shan. Significant spectral peaks are identified at 2-5, 60.2 and 213 years. Our reconstructed drought is significantly correlated with sea surface temperature in the North Atlantic and Indo-West Pacific Oceans. The linkages to the North Atlantic and Indo-West Pacific Oceans suggest the connection of moisture variations of Central Asia to the westerly circulation and tropical ocean-atmosphere systems.