树轮稳定同位素记录的天山区域（新疆-中亚）干湿变化历史及影响机制研究

Global warming has been confirmed, but regional climate change continues to be associated with great uncertainty. Global warming has altered precipitation and the hydrologic cycle in various regions. Because of their effects on large-scale synoptic patterns, mountain systems in central Asia modulate global-scale climate variability but are also highly sensitive to such variations. Tianshan Mountains, which is one of the most important water source areas, is dominated by westerly and plays an important role in global change research. It is vital to understand the fact of past changes of droughts and pluvials and explore its possible influence mechanism to the sustainable utilization of regional water resources. The length of instrumental meteorological observation data is limited, and thus, long-term climate change research has been restricted. We must find proxy data to understand past climate change. Fortunately, many Schrenk spruce (Picea schrenkiana Fisch. et Mey) forests are located in the Tianshan Mountains. The tree-ring growth of Schrenk spruce growing in arid and semi-arid mountainous environments is climate sensitive and is very suitable for the reconstruction of past climate change. . Dendroclimatology is an important method for examining pre-instrumental climate variations. With their precise dating, annual resolution, and comparability with meteorological instrument data, tree-ring data have become increasingly valuable for elucidating long-term climate dynamics in different regions of the world. However, previous studies in this area focus on the local change by using single and small range tree ring data, and there are few regional moisture/precipitation field reconstructions. . In this study, samples from fifty sites will be collected in representative Basin of Tianshan Mountains and fifty tree ring widths and ten isotope chronologies will be established using standard dendrochronological methods. We will establish the dendrochronology field using new built and existing chronologies, and the instrument observation climatic data, grid data of Climatic Research Unit (CRU), Palmer Drought Severity Index (PDSI) and Standardised Precipitation-Evapotransporation Index (SPEI) were combined together to analyze the response of tree ring width and isotope to moisture (precipitation, PDSI, SPEI and relative humidity) and its cause, and evaluate the potential of climate reconstruction by using stable isotope. We will reconstruct the field of historic moisture (precipitation, PDSI, SPEI and relative humidity) in the Tianshan Mountains using Rotated Empirical Orthogonal Function (REOF) and Point-by-Point Regression (PPR) methods and analyze the characteristics of moisture spatiotemporal change, reveal the typical feature of moisture changes in the last three hundred years in the westerly area. Meanwhile, we will extract historical drought events and produce a historical Atlas of drought. Furthermore, we will reveal the relationship between the moisture field and main factors of atmospheric circulation and air-sea interaction, and try to understand the mechanism of historic moisture variability. . This study may deepen understand for climate change law of decadal to centennial scale, its complexity and mechanism in central Asia. And it is further clarity the role of the arid central Asia in the global climate system. It will provide reference for the understanding of climate change of westerly area of Xinjiang and Central Asia.

天山是新疆和中亚最为重要的水源地，位于内陆干旱区和“西风模态”核心区，气候敏感，环境脆弱。理解该区域气候时空变化规律及影响机制对全球变化研究和区域水资源可持续利用至关重要。本研究拟在新疆-中亚的天山山区典型流域进行大范围树轮采样，建立至少50条宽度序列和10条树轮稳定碳氧同位素序列，分析天山山区树轮宽度和稳定碳氧同位素对气候的响应规律；基于大量的树轮宽度序列和稳定碳氧同位素参数，综合利用旋转经验正交分解（REOF）和点对点回归（PPR）方法重建天山面域历史干湿变化场（降水、PDSI、SPEI和相对湿度等），探讨过去300年天山干湿时空变化特征，提取主要极端干旱事件，构建天山区域历史干旱图集，进一步结合主要大气环流、海气作用和其它外强迫因子，探讨天山历史干湿时空变化主要的强迫因子，揭示主要的干湿时空变化影响机制。本研究为干旱区未来气候变化预估、水资源评价和管理及社会经济发展战略提供基础依据。

天山位于中亚内陆干旱区，气候敏感、环境脆弱，理解该区域干湿时空变化规律及影响机制对区域水资源可持续利用至关重要。本研究利用树木年轮气候学方法，在新疆、吉尔吉斯斯坦和哈萨克斯坦天山山区主要流域共采集了50个样点的1211棵树的2421根样芯，并建立了50条树轮宽度年表、8条树轮稳定碳同位素序列以及4条树轮稳定氧同位素序列；分析了不同海拔、不同树种、南北坡以及不同去趋势方法的树轮宽度和树轮稳定碳同位素对气候的响应规律及其主要的限制性气候因子；基于树轮宽度和稳定碳同位素综合重建了天山TS.Tuyuksuyskiy冰川物质平衡变化，分别重建了吉尔吉斯斯坦楚河流域、哈萨克斯坦准格尔阿拉套、伊犁地区、玛纳斯河流域、赛里木湖流域以及东天山过去200-400年的干湿变化；新重建并整合了天山山区典型区域15条气候序列，重建了覆盖中亚三国整个天山区域干湿变化场，明晰了天山区域历史干湿变化规律，提取了极端干旱年份，明确了天山区域历史干湿变化主要的影响因子。结果表明：天山山区过去500年降水趋势具有较好的一致性，但是降水绝对值局地性较强，天山山区存在两个强降水中心，分别为哈萨克斯坦东南部和中国伊犁河流域的巩乃斯，两地的年总降水量超过800mm；而天山南坡降水最少，年降水量不足220mm。1917是过去169年最为干旱的一年，1945和1926也为极端干旱年，1910年代是过去169年最为干旱的年代，发生了前所未有的持续性干旱事件，天山中心区域降水量增加趋势明显。整体而言，天山区域历史干湿变化受西风环流影响，天山水汽主要来自源于北大西洋、黑海等地。但是，天山降水变化及其影响因子仍存在一定的区域差异，西天山干湿变化主要受西风影响，而东天山与ENSO有一定关联。依托本项目，共发表研究论文13篇，其中SCI收录8篇；参编专著1部，软件著作权1项，完成硕士博士学位论文各1篇。本研究可为干旱区气象防灾减灾、水资源管理及未来气候变化预估提供基础依据。