Search

In this study, the regional tree-ring chronology of Picea crassifolia was used to estimate annual (September to August) streamflow of the Shiyang River for the period from AD 1765 to 2010. The linear regression model was stable and could explain 41.5% of the variance for the calibration period of 1955-2005. According to the streamflow reconstruction, dry periods with below average streamflow occurred in AD 1775-1804, 1814-1823, 1831-1856, 1862-1867, 1877-1885, 1905-1910, 1926-1932, 1948-1951, 1960-1963 and 1989-2002. Periods of relatively wet years are identified for AD 1765-1774, 1805-1813, 1824-1830, 1857-1861, 1868-1876, 1886-1904, 1911-1925, 1933-1947, 1952-1959, 1964-1988 and 2003-2010. Comparisons with the precipitation reconstructions from surrounding areas supplied a high degree of confidence in our reconstruction. Our reconstructed streamflow is significantly correlated with sea surface temperature in the eastern equatorial Pacific Ocean and the North Atlantic Ocean. The Multitaper spectral and correlation analyses also suggested that the reconstructed streamflow variation in the Shiyang River could be associated with large-scale atmospheric-oceanic variability, such as El Niño-Southern Oscillation (ENSO). The linkages among the streamflow reconstruction, NAO and ENSO suggest the connection of regional streamflow variations to the Asian monsoon and westerlies circulations. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In Central Asia, tree rings provide one of the best sources of paleoclimatological information. However, dendroclimatology has not been widely applied in the coniferous forests of Central Asia. Tree cores of Picea Schrenkiana from four sites in the Hutubi River Basin were developed into a 606-year tree-ring width chronology. The analyses showed that the tree-ring width indices highly correlate with mean April–May PDSI in the Hutubi River Basin. Mean April–May PDSI of the Hutubi River was reconstructed using the tree-ring data with 41.5% of the variance explained. The reconstructed series contains both high- and low-frequency climate signals. Our new PDSI reconstruction agrees reasonably well with the dry and wet periods previously estimated from tree rings in western Tien Shan. The results reveal common climatic extremes over much of Central Asia. Spatial analysis shows that the PDSI reconstructions have strong common signals for the Tien Shan. The first principal component of PDSI reconstructions in Tien Shan is significantly correlated with sea surface temperature in the eastern equatorial Pacific Ocean and Atlantic Ocean. The linkages to the Atlantic and Pacific Oceans suggest the connection of regional moisture variations to the Asian monsoon and the Westerlies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]