气候变化领域集成服务门户

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.