Hydroclimate variation during the Mystery Interval in the East Asian Summer Monsoon area
Hydroclimate variation during the Mystery Interval in the East Asian Summer Monsoon area
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东亚夏季风区神秘区间水文气候变化
DOI：
10.1016/j.quascirev.2021.107075
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发表时间：
2021
影响因子：
4
通讯作者：
Peng Ping'an
中科院分区：
文献类型：
--
作者：
Zhao Bingyan;Huang Xianyu;Hu Jianfang;Shu Junwu;Wang Weiming;Peng Ping'an
17.5- 14.5kaBP神秘期（MI）中低纬和高纬古气候记录的不一致性尚未得到很好的解决。通过对定南湿地沉积岩样正构烷烃的分子分布和碳同位素组成以及有机质的元素和同位素组成的分析，重建了东亚夏季风（EASM）区南部的古水文学，并对MI期间亚洲夏季风（ASM）区的水文气候变化进行了空间对比。DN岩心的多项指标证实了在约100 ℃时发生了干-湿和湿-干转变。17.5 ka BP和16.0 ka BP。与DN记录的干湿转换同步，略低纬度的中南半岛半岛变得更加湿润。相比之下，长江中游地区在更北北方纬度变得稍微干燥，华北地区没有表现出水文变化。此外，在MI中期，中南半岛（10-20°N，约16.5kaBP）和东亚运动南部（23-27°N，约16.0kaBP）的干湿转换较强，而在中扬子区（28-32°N）和华北（35-40°N）几乎不存在。第一次水文转折可能与热带辐合带的同步南移和北方半球的冷却导致的西风急流有关。第二次水文转变的缺乏被解释为ITCZ和西风急流的解耦的结果所造成的ITCZ的延迟形成，由于南半球的变暖。这项研究揭示了MI期间水文气候变化的空间差异，并强调了西风急流和ITCZ之间的耦合对ASM地区降雨的潜在影响。
The inconsistency of paleoclimate records between the mid-low and high latitudes during the Mystery Interval (MI, 17.5–14.5 ka BP) is not well resolved. To provide a mechanism analysis, this study conducts spatial comparisons of hydroclimate changes in the Asian Summer Monsoon (ASM) region during the MI by reconstructing the paleohydrology of the south of East Asian Summer Monsoon (EASM) region using the molecular distributions and carbon isotope ratio ofn-alkanes, as well as elemental and isotopic composition of bulk organic matter, in a sedimentary core retrieved from Dingnan (DN) wetland. The multiple indices of the DN core confirmed the occurrence of dry-wet and wet-dry transitions at ca. 17.5 ka BP and 16.0 ka BP, respectively. Synchronous with the dry-wet transition in the DN records, the Indochina Peninsula at a slightly lower latitude became wetter. In contrast, the middle Yangtze region at a more northern latitude became slightly drier, and North China did not show a hydrological variation. Moreover, the wet-dry transition at the mid-MI was strong in the Indochina Peninsula (10–20°N, at about 16.5 ka BP) and the southern EASM region (23–27°N, at about 16.0 ka BP) but was nearly absent in the middle Yangtze region (28–32°N) and North China (35–40°N). The first hydrological transition possibly connects with the synchronous southward movement of the Intertropical Convergence Zone (ITCZ) and the westerly jet caused by the cooling of the Northern Hemisphere. The absence of the second hydrological transition is interpreted as a result of the decoupling of the ITCZ and the westerly jet caused by the delayed formation of the ITCZ due to the warming of the Southern Hemisphere. This study reveals spatial differences in the hydroclimate variations during the MI and highlights the potential influence of coupling between the westerly jet and the ITCZ on rainfall in the ASM region.