Deglacial 未¹⁸O and hydrologic variability in the tropical Pacific and Indian Oceans

详细信息    查看全文

• 作者：Fern T. Gibbons ; Delia W. Oppo ; Mahyar Mohtadi ; Yair Rosenthal ; Jun Cheng ; Zhengyu Liu ; Braddock K. Linsley
• 关键词：Indo-Pacific ; Eastern Equatorial Pacific ; 未18O of seawater ; deglaciation ; heat transport
• 刊名：Earth and Planetary Science Letters
• 出版年：1 February, 2014
• 年：2014
• 卷：387
• 期：Complete
• 页码：240-251
• 全文大小：3350 K

文摘

Evidence from geologic archives suggests that there were large changes in the tropical hydrologic cycle associated with the two prominent northern hemisphere deglacial cooling events, Heinrich Stadial 1 (HS1; 鈭?9 to 15 kyr BP; kyr BP = 1000 yr before present) and the Younger Dryas (鈭?2.9 to 11.7 kyr BP). These hydrologic shifts have been alternatively attributed to high and low latitude origin. Here, we present a new record of hydrologic variability based on planktic foraminifera-derived 未¹⁸O of seawater (未¹⁸O_sw) estimates from a sediment core from the tropical Eastern Indian Ocean, and using 12 additional 未¹⁸O_sw records, construct a single record of the dominant mode of tropical Eastern Equatorial Pacific and Indo-Pacific Warm Pool (IPWP) hydrologic variability. We show that deglacial hydrologic shifts parallel variations in the reconstructed interhemispheric temperature gradient, suggesting a strong response to variations in the Atlantic Meridional Overturning Circulation and the attendant heat redistribution. A transient model simulation of the last deglaciation suggests that hydrologic changes, including a southward shift in the Intertropical Convergence Zone (ITCZ) which likely occurred during these northern hemisphere cold events, coupled with oceanic advection and mixing, resulted in increased salinity in the Indonesian region of the IPWP and the eastern tropical Pacific, which is recorded by the 未¹⁸O_sw proxy. Based on our observations and modeling results we suggest the interhemispheric temperature gradient directly controls the tropical hydrologic cycle on these time scales, which in turn mediates poleward atmospheric heat transport.