Tao Wang , Qin Wen , Jian Liu , Liang Ning , Mi Yan , Weiyi Sun
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引用次数: 0
Abstract
The upwelling-induced productivity in the Arabian Sea is often used to infer changes in the Indian summer monsoon (ISM). However, the evolution of ISM based on these productivity records is inconsistent with other moisture records during the last deglaciation (20-11ka), leading to uncertainty about ISM variations. Here, we use an isotope-enabled transient climate experiment (iTraCE) to investigate the reasons for this discrepancy, suggesting that the discrepancy arises from different driving processes between the ISM rainfall and Arabian Sea upwelling. The ISM rainfall decreases during Heinrich Stadial 1 (HS1) and increases during Bølling-Allerød (BA), driven by moisture convergence. However, the Arabian Sea upwelling is more complex, with coastal and open sea upwelling responding differently to climatic changes. The coastal upwelling along the Oman coast intensifies from the Last Glacial Maximum (LGM) to BA primarily due to strengthening coastal winds driven by increased local land-sea thermal contrast. In contrast, open sea upwelling exhibits a more nuanced pattern. During HS1, it increases near the Oman coast but weakens offshore, while during BA warming, it weakens over a large part of the open sea region. These variations in open sea upwelling are attributed to changes in the meridional movement of monsoon low-level jet with a slight northward shift during HS1 and a significant shift during BA, affecting the extent of Ekman pumping contraction. Our research demonstrates that western Arabian Sea upwelling does not accurately reflect changes in ISM rainfall intensity during the last deglaciation due to these divergent driving processes. This study provides new insights into the upwelling-ISM rainfall relationship from a millennial-scale perspective, contributing to a more nuanced understanding of paleoclimatic changes in the region.
期刊介绍:
Quaternary Science Reviews caters for all aspects of Quaternary science, and includes, for example, geology, geomorphology, geography, archaeology, soil science, palaeobotany, palaeontology, palaeoclimatology and the full range of applicable dating methods. The dividing line between what constitutes the review paper and one which contains new original data is not easy to establish, so QSR also publishes papers with new data especially if these perform a review function. All the Quaternary sciences are changing rapidly and subject to re-evaluation as the pace of discovery quickens; thus the diverse but comprehensive role of Quaternary Science Reviews keeps readers abreast of the wider issues relating to new developments in the field.