Hydrological variability in the western tropical Pacific over the past 700 kyr and its linkage to Northern Hemisphere climatic change
Hydrological variability in the western tropical Pacific over the past 700 kyr and its linkage to Northern Hemisphere climatic change
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过去700 kyr西热带太平洋水文变化及其与北半球气候变化的联系
DOI：
10.1016/j.palaeo.2017.12.039
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Qin Bingbin
中科院分区：
文献类型：
--
作者：
Jia Qi;Li Tiegang;Xiong Zhifang;Steinke Stephan;Jiang Fuqing;Chang Fengming;Qin Bingbin
El Niño/南方涛动（ENSO）事件和热带辐合带（ITCZ）的纬向移动引起了热带西太平洋（WTP）大尺度的水文变化。然而，关于ENSO和ITCZ变化对WTP水文气候的作用及其与北半球气候变化在冰期-间冰期时间尺度上的联系仍存在争议。因此，我们利用从WTP北部恢复的IMAGES Core MD06-3047B中经冰体积校正的海水δ18O （δ18Osw-ice，盐度的代表）和海温（SST）记录，研究了近700 kyr WTP北部的水文气候。浮游有孔虫aglobigerinoides橡胶基Mg/Ca-SST和δ 18ows -冰记录显示了明显的冰期-间冰期变化。δ 18ows - icerrecord表明，研究区冰期条件较新鲜，降水较间冰期多。我们的结果与数值模式的模拟结果很好地吻合，这也表明了WTP北部的冰川更新。WTP的冰川更新很可能与大西洋经向翻转环流（AMOC）的大幅减弱和/或海平面变化导致的海洋大陆暴露有关，这导致太平洋沃克环流增强和/或ITCZ向南移动。此外，来自WTP和热带东太平洋（ETP）的海温记录表明，热带太平洋纬向海温梯度增强，从而导致La Niña-like条件，这可能是冰川时期WTP较新鲜的条件。此外，我们的降水记录与中国洞穴δ18O记录处于反相，支持WTP与东亚在轨道时间尺度上的降水变化趋势相反的观点。
El Niño/Southern Oscillation (ENSO) events and latitudinal shifts of the Intertropical Convergence Zone (ITCZ) cause large scale hydrologic changes in the western tropical Pacific (WTP). However, there is still a debate on the role of ENSO and ITCZ shifts on the hydroclimate in the WTP and their linkage to Northern Hemisphere climate change on glacial-interglacial timescales. For that reason, we present ice volume-corrected seawater δ18O (δ18Osw-ice, a proxy for salinity) and sea surface temperature (SST) records from IMAGES Core MD06-3047B recovered from the northern WTP to investigate the hydroclimate in the WTP during the last 700 kyr. Planktic foraminiferaGlobigerinoides ruberbased Mg/Ca-SST and δ18Osw-icerecords reveal distinct glacial-interglacial variations. The δ18Osw-icerecord shows that our study site is characterized by fresher conditions and thus higher precipitation during glacials than during interglacials. Our results are in good agreement with numerical model simulations, which also suggest a glacial freshening in the northern WTP. A glacial freshening of the WTP is most likely related to a substantial weakening of the Atlantic Meridional Overturning Circulation (AMOC) and/or exposure of the Maritime Continent due to sea level changes which resulted in an enhanced Pacific Walker circulation and/or southward shift of the ITCZ. In addition, SST records from the WTP and the eastern tropical Pacific (ETP) suggest an enhanced tropical Pacific zonal SST gradient and thus La Niña-like conditions, which may have contributed to fresher conditions in the WTP during glacial periods. Besides, our rainfall record is in antiphase to the Chinese speleothem δ18O records, supporting the idea of an opposing trend in precipitation changes between the WTP and East Asia on orbital timescales.