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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]

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]

Seven different tree-ring parameters (tree-ring width, earlywood width, latewood width, maximum density, minimum density, mean earlywood density, and mean latewood density) were obtained from Qinghai spruce ( Picea crassifolia) at one chronology site in the Hexi Corridor, China. The chronologies were analyzed individually and then compared with each other. Growth-climate response analyses showed that the tree-ring width and maximum latewood density (MXD) are mainly influenced by warm season temperature variability. Based on the relationships derived from the climate response analysis, the MXD chronology was used to reconstruct the May-August maximum temperature for the period 1775-2008 A.D., and it explained the 38.1% of the total temperature variance. It shows cooling in the late 1700s to early 1800s and warming in the twentieth century. Spatial climate correlation analyses with gridded land surface data revealed that our warm season temperature reconstruction contains a strong large-scale temperature signal for north China. Comparison with regional and Northern Hemisphere reconstructions revealed similar low-frequency change to longer-term variability. Several cold years coincide with major volcanic eruptions. [ABSTRACT FROM AUTHOR]

June–July mean temperature was reconstructed back to 1698 for the southern Altai Mountains in eastern Central Asia using four temperature series based on tree-ring widths. The reconstruction explains 48% of the variation in the observed temperature from 1962 to 2003. Warm periods occurred during 1714–1732, 1753–1776, 1800–1840, 1866–1886, 1893–1911, and 1943–1969, while the periods of 1708–1713, 1733–1752, 1777–1799, 1841–1865, 1887–1892, 1912–1942, and 1970–1993 were relatively cold. Power spectral and wavelet analyses demonstrated the existence of significant 50-, 14-, 2.8-, and 2.5-year cycles of variability. The results of a spatial correlation analysis suggested that this temperature reconstruction contains climatic signals for a large area of Central Asia. After employing a 21-year low-pass filter, the coherence of the newly reconstructed series with a regional temperature reconstruction for Central Asia and also with a local temperature reconstruction for the Zajsan Lake area of East Kazakhstan indicates that our temperature reconstruction captures broad-scale regional climatic variations in the low-frequency domain. [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]

A tree-ring width chronology developed from a site of Larix sibirica at the eastern end of Tien Shan was employed to study the drought variability of east Xinjiang. The drought reconstruction spanning 1785–2009 was developed by calibrating tree-ring data with standardized precipitation-evapotranspiration index (SPEI), an index indicating regional moisture conditions. The SPEI reconstruction accounted for 45.8% of actual October–August SPEI variance during their common period (1957–2009). Wet periods with SPEI above the 225–year mean occurred around 1785–1799, 1821–1833, 1842–1858, 1864–1873, 1887–1898, 1905–1925, 1937–1948, 1954–1962, 1969–1983 and 1991–1993, while dry periods (SPEI below the mean) occurred in 1800–1820, 1834–1841, 1859–1863, 1874–1886, 1899–1904, 1926–1936, 1949–1953, 1963–1968, 1984–1990 and 1994–2009. There was an aridity aggravation trend since the mid-1980s in east Xinjiang. Our results also suggest that east Xinjiang was influenced by the interactions between the Asian monsoon and the Westerlies circulations. [ABSTRACT FROM AUTHOR]

Abstract: July–June precipitation has been reconstructed back to A.D. 1464 for the Baluntai region on the southern slope of the central Tien Shan Mountains, China, using the Picea schrenkiana tree-ring width. The reconstruction explains the variance of 51% in the observed precipitation from 1959 to 2005. By employing a 21-year moving average to the reconstruction, nine periods with above average reconstructed precipitation comprised ∼1474–1503, 1550–1577, 1588–1619, 1658–1713, 1790–1812, 1833–1867, 1890–1907, 1923–1944, and 1988–1995∼; eight periods with below average reconstruction consisted of 1504–1549, 1578–1587, 1620–1657, 1714–1789, 1813–1832, 1868–1889, 1908–1922 and 1945–1987. The wet/dry periods of the reconstructed precipitation correspond well with other reconstructions. Some droughts in the historical documents are also precisely captured in the reconstruction. Precipitation variations for the southern slope of the central Tien Shan Mountains are roughly synchronous with that of the northern slope in the recent ∼300 year. Power spectral and wavelet analysis demonstrated the existence of significant ∼100-y, ∼60-y, ∼50-y, ∼16-y, ∼10-y and ∼2-y cycles of variability. [Copyright &y& Elsevier]