College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
Int J Biometeorol. 2023 Jan;67(1):181-194. doi: 10.1007/s00484-022-02397-w. Epub 2022 Oct 28.
The overlap region between the eastern fringe of the Asian westerly region and the temperate continental-monsoon climate transition zone is sensitive to climate changes and is characterized by fragile ecosystems. Uncovering the long-term historical climate variability patterns in this region is necessary. A standardized tree-ring width chronology was constructed based on the tree-ring samples collected from four representative tree species in four typical areas in the overlap region, and the 203- to 343-year annual mean minimum temperature series in the overlap region were reconstructed. The reconstructed series overlapped well with extreme climate events and low-temperature periods recorded in historical data. Therefore, the reconstructed model is stable and reliable. As suggested by the reconstructed series, the annual average minimum temperature in the overlap region changes sharply from east to west, and the periodicity change in the overlap region shows a trend of gradually weakening from the east and west ends to the middle. In the nineteenth century, the high-latitude area was in the high-temperature period, and the entire overlap region experienced significant low-temperature periods lasting 20-45 years until the 1950s. The western part had an earlier low-temperature period start time, a longer cooling duration, and a slower cooling rate than the central part. The overlap region experienced a significant warming period in approximately the last half-century, with temperatures increasing faster in the western and eastern parts than in the central part. The temperature variability in the overlap region was more intense in the last two centuries, with shorter periodicities and a larger proportion of cold periods. The central and western parts of the Asian westerly region, the mid- to high-latitude regions of the transition zone, and the overlap region experienced significant low-temperature periods or drastic cooling trends (the Little Ice Age) in the first half of the nineteenth century and significant warming trends afterwards due to global warming. The influences of these changes may have been exacerbated by the westerly circulation. The results of this study provide new insights into the use of dendroclimatology to extract temperature series in the Asian westerly region and the transition zone and a reference for research on global climate change.
该重叠区域位于亚洲西风带的东部边缘和温带大陆性季风气候过渡带之间，对气候变化敏感，生态系统脆弱。揭示该区域的长期历史气候变化模式是必要的。本研究基于在该重叠区域四个典型地区的四个代表性树种的树木样本，建立了一个标准化的树木年轮宽度年表，并重建了该重叠区域的 203-343 年的年均最低温度序列。重建序列与历史数据中记录的极端气候事件和低温期很好地吻合，因此重建模型是稳定可靠的。根据重建序列，重叠区域的年均最低温度从东向西急剧变化，重叠区域的周期性变化呈现出从东、西端到中部逐渐减弱的趋势。在 19 世纪，高纬地区处于高温期，整个重叠区域经历了长达 20-45 年的显著低温期，直到 20 世纪 50 年代。西部低温期开始时间更早，冷却持续时间更长，冷却速度更慢。在过去的半个世纪里，重叠区域经历了一个显著的变暖期，西部和东部的升温速度比中部更快。在过去的两个世纪里，重叠区域的温度变化更加剧烈，周期性更短，冷期比例更大。亚洲西风带的中部和西部、过渡带的中高纬度地区以及重叠区域在 19 世纪上半叶经历了显著的低温期或剧烈的冷却趋势（小冰期），之后由于全球变暖，又经历了显著的变暖趋势。这些变化的影响可能因西风环流而加剧。本研究结果为利用树木年代学提取亚洲西风带和过渡带的温度序列提供了新的见解，为研究全球气候变化提供了参考。
