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A regional tree‐ring width chronology of Schrenk spruce (Picea schrenkiana) was used to determine the annual (previous July to current June) streamflow of the Kuqa River in Xinjiang, China, for the period of 1414–2015. A linear transformation of the tree‐ring data accounted for 63.9% of the total variance when regressed against instrumental streamflow during 1957–2006. The model was validated by comparing the regression estimates against independent data. High streamflow periods with a streamflow above the 602‐year mean occurred from 1430–1442, 1466–1492, 1557–1586, 1603–1615, 1687–1717, 1748–1767, 1795–1819, 1834–1856, 1888–1910 and 1989–2015. Low streamflow periods (streamflow below the mean) occurred from 1419–1429, 1443–1465, 1493–1556, 1587–1602, 1616–1686, 1720–1747, 1768–1794, 1820–1833, 1857–1887 and 1911–1988. The reconstruction compares well with the tree‐ring‐based streamflow series of the Tizinafu River from the Kunlun Mountains; both show well‐known severe drought events. The streamflow reconstruction also shows highly synchronous upward trends since the 1980s, suggesting that streamflow is related to Central Asian warming and humidification. Thus, the influences of the extremes and the persistence of low streamflows on local society may be considerable. Climatic changes in the watershed may be responsible for the change in the hydrologic regime of the Tarim Basin observed during the late twentieth century. [ABSTRACT FROM AUTHOR]

Central Asia is the world's largest non-zonal arid area, with rare and uneven precipitation. As a sensitive area of global change and with a vulnerable ecological environment, Central Asia is largely affected by global change. Various long-lived conifer species widely distributed in the mountains of Central Asia have become an important proxy for studying historical climatic, hydrological, and vegetation changes in this region. This paper reviews research progress on tree rings in Central Asia; specifically, the current state of research is addressed, highlights and bottleneck problems associated with the research are analyzed and discussed, and suggestions and prospects for further study of dendrochronology in this area are proposed. [ABSTRACT FROM AUTHOR]

ABSTRACT The temperature of snow at 10 discrete vertical levels in the snow pack was measured using automatic temperature recorders at 10 min intervals following 5 snowfalls between January and March 2009 at the Tianshan Station for Snow Cover and Avalanche Research. The amplitude of the diurnal fluctuation in the temperature during the measurement run of 10 March 2009, when the snow was melting, was 1.85 times greater than during the measurement run of 15 February, when snow was accumulating. Analysis of the vertical temperature gradient for all five measurement runs shows that the temperature gradient of the snow was at a maximum value at the snow surface. The maximum snow temperature gradient was measured during the run of 21 January and was 4.46 times greater than during the run of 15 February. The temperature gradient was approximately zero 30 cm below the snow surface. Analysis of the characteristics of the snow temperature and the daily mean volumetric moisture content of the snow leads to the conclusion that the snow cover in the western Tianshan Mountains can be divided into stable, interim, and melting stages. A critical snow volumetric moisture content of 0.1% separates the stable and interim stages, while a volumetric moisture content of 0.3% separates the interim and melting stages. [ABSTRACT FROM AUTHOR]

An annual ( July to June) precipitation reconstruction for the period AD 1760-2010 was developed from a Picea crassifolia regional tree-ring chronology from two sites in the northern mountainous region of the Hexi Corridor, NW China. This reconstruction explains 52.1% of the actual precipitation variance during the period 1951 to 2010. Spatial correlations with gridded land-surface data reveal that our reconstruction contains a strong regional precipitation signal for the Hexi Corridor and for the southern margin of the Badain Jaran Desert. Significant spectral peaks were identified at 31.9, 11.1, 8.0, 7.0, 3.2, 2.6 and 2.2 years. A large-scale comparison indicates that our reconstruction is more consistent with climate records of a Westerly-dominated Central Asia, and that the Westerlies have a greater impact on the precipitation in this region than the Asian summer monsoon. Our reconstructed precipitation series is significantly correlated with sea-surface temperature ( SST) in the tropical Atlantic Ocean (positive), the tropical Indian Ocean (positive), the western tropical Pacific Ocean (positive), and the western North Pacific Ocean (negative). The spatial correlation patterns between our precipitation reconstruction and SSTs of the Atlantic and Pacific Oceans suggest a connection between regional precipitation variations and the high-mid-latitude northern atmospheric circulations ( Westerlies and Asian summer monsoon). [ABSTRACT FROM AUTHOR]

In this paper, ring-width chronologies of pine trees ( Pinus sylvestris var. mongolica) from one sampling site in the northern Greater Higgnan Mountains, China, were constructed. The results of growth-climate responses show that mean temperature is the limiting factor affecting radial growth of pine trees in the study area. Consequently, mean temperature from May to October from 1717 to 2008 has been reconstructed using the standard chronology. For the calibrated period (1957-2008), the explained variance of the reconstruction is 57%. The characteristics of the reconstruction expose that mean temperature has increased since the 1970s, and the decade 2000s and 1990s are also ranked as the warm decades on record. However, this period from 1970s to now is not exceptional within the past 300 years. By applying an 11-year moving average to the reconstruction, three warm periods and three cold periods are evident. The warm and cold periods of the reconstructed mean temperature correspond well with other reconstructions. Power spectral and wavelet analysis demonstrated the existence of significant ∼70- and ∼100-year cycles of variability. Furthermore, the reconstruction and North Atlantic Oscillation Index showed a significant positive correlation ( r = 0.34, n = 136, p < 0.0001). Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Wood from Siberian larch ( Larix sibirica Ledeb.) was collected in Hoboksar County, Xinjiang. Mean latewood densities (LWD) were measured by X-ray densitometry; individual series were first cross-dated and then combined to form a standard chronology. We developed a warm-season (June-August) temperature reconstruction of Zajsan Lake area in East Kazakhstan that spans 1600-2002 based on the standard chronology (LWD). The climate/tree-growth model accounts for 39.1% of the temperature variance from 1901 to 2002 and shows cold phase during the late 1600s early 1700s followed by a warmer period, with cooling again in the late 1700s early 1800s. Several severely cold warm seasons coincide with major volcanic eruptions. Some of the temperature variations also correspond to variations in solar activity. The similarities in trends of the Zajsan chronology (LWD) and the Qinghe chronology (LWD) in Altai Mountain show that there are common large-scale climatic forcings in Central Asian. The low-frequency change of temperature reconstruction is correlated positively with Northern Hemisphere temperatures. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Chemical surveys of snow were carried out in the upper reaches of the Kunnes River, a tributary of the Yili River in East Tienshan Mountains, China. Some surprisingly high values of sodium and potassium (K[sup +] + Na[sup +] ) ranging from 4.44 to 8.99 mg/1 compared with other data from neighboring areas are detected. Moreover, some relative high values of SO[sup 2-, sub 4] with mean concentration 15.8mg/1 for new snow and 14.40mg/l for deposited snow, ranging from 10.43 to 23.71 mg/1 are also found. Therefore, it is inferred that the sodium and potassium (K[sup +] + Na[sup +]) are in the forms of sulfate and that the sources of the sulfate are deserts and some dried lakes in Central Asia. It is also found that there is obviously spatial variation of ions such as K[sup +] + Na[sup +], Ca[sup 2+] +, SO[sup 2-, sub 4] and HCO[sup -, sub 3]. The concentrations of K [sup +] + Na[sup +] and SO[sup 2, sub 4], and that of Ca[sup 2+] and HCO[sup -, sub 3] have similar spatial pattern. The temporal pattern of ion concentration of new snow is considered to be mainly controlled by the depth and area of snow cover in the study area and in the areas to the west. [ABSTRACT FROM AUTHOR]

Seven different tree-ring parameters were obtained from Chinese pine (Pinus tabulaeformis) in the Changling Mountains, China. The chronologies were analyzed individually and then compared with each other. The climate response analysis shows that total precipitation (September-July) is the main factor limiting the radial growth of Chinese pine in the Changling Mountains. Thus, the residual earlywood width chronology was used to estimate precipitation (September-July) for the period AD 1691-2006, and explained 46.9% of the precipitation variance. Drought events in our reconstruction are compared to historical archives for Gansu and north-central China. The results reveal the climatic extremes over much of Gansu. Some events have had profound impacts on the Gansu people over the past several centuries. Spatial analysis shows that the precipitation reconstruction has strong common signals for North-central China. The reconstructed series is correlated significantly with Helan Mountains Palmer drought severity index (PDSI), as well as with previous results from Jiuquan, Shandan, Huashan, Luya Mountains, and even the state of Mongolia. Our results suggest that some dry periods are coincident with solar minima over the past several hundred years. Multitaper spectral analysis reveals the existence of significant 24.4-year, 12.2-year, and 2.4- to 3.4-year periods of variability.