Abstract
The Tianshan Mountain is the largest mountain range in Central Asia, and the source area of many river systems. Changes in precipitation result in significant alterations to regional hydrological processes. Lake sediment from the Tian Shan representative of the last 90 years was chosen as the object of this research study. The grain-size data were used in conjunction with instrumental data to provide a method for determining changes in paleoprecipitation. The results showed the three-point moving average curve of the silty fraction content with a size of 16 to 32 μm to be significantly consistent with the curve of total precipitation from April to September since 1950. The total content of clay and fine-silty fraction (0–16 μm) was clearly consistent with the monthly precipitation in July. The total precipitation from April to September showed a significant downward trend from 1930 to 1975, and then an overall increasing trend beginning in 1975, which may have been influenced by the North Atlantic Oscillation. The change in precipitation reconstructed by the grain size of lake sediments was significantly different from the high-resolution gridded datasets (Climatic Research Unit Time-Series version 4.04) because of the lack of data from meteorological stations in China before 1950. The conclusions of this study are significant for evaluating the validity of climatic research unit (CRU) data in arid areas of Western China. In addition, the results of this study serve as a bridge between modern instrumental records and long time-scale paleoclimate research and provide important reference values for future reconstructions of long time-scale paleoclimate.
Highlights
Located in the hinterland of Eurasia, the arid region of Central Asia has a typical continental arid climate and one of the most vulnerable terrestrial ecosystems [1]
Based on the distribution of 137 Cs in lake sediments within the northern hemisphere, it is believed that the occurrence of 137 Cs residual layers corresponds to the start of global nuclear testing in 1954 [43], and the main peak at 20 cm may correspond to the Chernobyl nuclear leak in the former Soviet Union in 1986 [44,45]
The results suggested that the grain size of Lake Ta-Lung-Chi in the Tianshan Mountains sensitively recorded the information of precipitation changes
Summary
Located in the hinterland of Eurasia, the arid region of Central Asia has a typical continental arid climate and one of the most vulnerable terrestrial ecosystems [1]. A comprehensive understanding of the environmental issues resulting from climate change and human activities in Central Asia is of great significance for the ecological protection and improvement of the region, national security, and sustainable development of the social economy [2,3,4]. Over the past 100 years, air temperature in the arid region of Central Asia, which is mainly controlled by westerly winds, has clearly shown an increasing trend [5,6]. Annual precipitation in this region shows an overall increasing trend, but with spatial differences [7,8].
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