Yong Zijuan, Feng Zhaodong
College of Geography and Environmental Science, Henan University, Jinming Street, Kaifeng 475004, China; Provincial Key Laboratory of Earth System Observation and Modeling, Henan University, Jinming Street, Kaifeng 475004, China.
Sci Total Environ. 2024 Nov 25;953:176249. doi: 10.1016/j.scitotenv.2024.176249. Epub 2024 Sep 12.
The northwestern half of the Chinese Loess Plateau (i.e., the examined area) is reported to have been sensitive to the East Asian Summer Monsoon (EASM) and might have also been exposed to the influence of the Indian Summer Monsoon (ISM) during the Holocene. This study utilizes the already reported pollen data from four high-resolution fossil pollen sequences to quantitatively reconstruct the Holocene mean annual precipitation (Pann) in the examined area. It also incorporates those quantitative precipitation reconstructions from the same area reported by others to delineate the regional Pann patterns. It finally brings the regional Pann patterns into the perceived forcing contexts to explore the underlying mechanisms. Our delineation shows that the Holocene Pann exhibits different temporal trends between the western part and the northern part of the Chinese Loess Plateau. That is, the "higher-than-average" Pann occurred in the early mid-Holocene from ~10.0 to ~5.5 cal. kyr BP in the western part and the "higher-than-average" Pann occurred in the late mid-Holocene from ~8.0 to ~2.5 cal. kyr BP in the northern part. We propose that the Pann differences between the western part and the northern part might have been associated with two mechanisms: (1) differences in the thermal sensitivity to the solar insolation between the Indian Ocean and the Pacific Ocean, and (2) differences in terms of the relative importance of precipitable water vapor transports either from the ISM or from the EASM between the western part and the northern part.
据报道，中国黄土高原的西北半部（即研究区域）在全新世期间对东亚夏季风（EASM）敏感，并且可能也受到了印度夏季风（ISM）的影响。本研究利用已报道的来自四个高分辨率化石花粉序列的花粉数据，定量重建研究区域的全新世年均降水量（Pann）。它还纳入了其他研究人员报道的同一区域的定量降水重建结果，以描绘区域Pann模式。最后，将区域Pann模式置于已知的强迫背景下，以探索潜在机制。我们的描绘结果表明，全新世Pann在中国黄土高原西部和北部呈现出不同的时间趋势。也就是说，“高于平均水平”的Pann在西部出现在全新世中早期，约为公元前10.0至5.5 cal. kyr，而在北部出现在全新世中晚期，约为公元前8.0至2.5 cal. kyr。我们认为，西部和北部之间的Pann差异可能与两种机制有关：（1）印度洋和太平洋对太阳辐射的热敏感性差异，以及（2）西部和北部之间来自ISM或EASM的可降水水汽输送的相对重要性差异。
