末次冰期以来“西太暖池—主流系区”温、盐梯度对全球快速气候变化事件的响应

The Western Pacific Warm Pool (WPWP)and the Western Boundary Current (WBC, the Kuroshio and its extension ), as one of the most dynamic region of heat and moisture, plays a crucial role in the Earth climate system. Here in this proposal, 6 gravity sediment cores, distributed in the large section from the WPWP to the WBC area, are selected. Based on detailed AMS14C dates and δ18O stratigraphy, by using Uk’37-derived and/or Mg/Ca-derived paleo-thermometer, the SST and SSS records since the last glacial of the WPWP and the WBC area will be established. Moreover, by high-resolution organic geochemistry records (such as the content and isotopic composition of carbon and nitrogen, the content of long-chain n-alkane, n-alkanol and unsaturated alkenone) the paleoproductivity history and the terrestrial input (paleo-rainfall) history of the WPWP and WBC area will be reconstructed. Correlations of these different records (such as the SST, SSS, paleoproductivity and paleo-rainfall) from the WPWP-WBC section, the comparable series of paleocenography and paleoclimate records from the “WPWP-Kuroshio Source area-Kuroshio main flow-extension flow area” will be obtained. Based on these records, we will investigate the thermal state of the WPWP and the intensity of Kuroshio during the LGM, in the deglaciation period and in the Holocene optimum. And we will explore the imprints of the rapid climate changes (RCC) (such as the Heinrich events, the Younger Dryas, the 8.2ka BP cold event, the Holocene Bond-cycles and the Little Ice Age) on different areas. Then, we will give clear frequency, magnitude and form records of the similarities and differences, in response for the RCC, from the WPWP to the WBC and its extension region. Furthermore, we will trace the teleconnection between the RCC and the low latitude ENSO, the intensity of the East Asian Monsoon (EAM) and the latitudinal migration of the Intertropical Convergence Zone (ITCZ), in base of the comparisons of our RCC records from WPWP-WBC with ENSO, EAM, ITCZ records.

西太暖池及主流系作为全球气候变化的热量-水汽交换最活跃区域，在全球气候变化中起着关键作用。通过跨“暖池-黑潮主流系-续流区”纬向大断面6个岩芯，建立高精度AMS14C年代及同位素地层，利用Mg/Ca及UK’37古温度重建方法结合δ18O同位素提取不同区域的古海水温度、盐度记录，利用同位素地球化学、有机地球化学指标重建古海洋生产力及陆源输入（降水）历史。重建“暖池区-黑潮源区-黑潮主流轴-续流区”末次冰期以来古海水温、盐梯度记录。探讨LGM期间、末次冰消期以及全新世大暖期时暖池水热状态以及黑潮流系的强弱。重点解剖“暖池-主流系”在YD以及8.2ka这类典型快速气候变化事件中温、盐特征（频率及变化幅度），给出温盐变化的边界条件。通过对比研究探寻其与低纬ENSO过程、东亚季风强弱变化以及ITCZ南北移动之间的联系。弥补现代仪器观测记录在时限上的不足，为研究长期气候变化及气候环境预测提供边界条件。

西太暖池及主流系统作为全球气候变化的热量-水汽交换最活跃区域，在全球气候变化中起着关键作用。本项目通过跨“暖池-主流系”大断面的6个岩芯，提取不同区域的古海水温度、盐度记录。探讨了LGM期间、末次冰消期以及全新世大暖期时暖池-流系的水热状态。重点探究了H事件、YD、8.2ka、全新世Bond旋回以及小冰期等快速气候变化事件中“暖池-主流系”不同区域的温盐特征（事件记录的频度、幅度和表现形式的异同）。我们的研究发现“暖池-主流系”不同区域对于快速气候变化事件的响应模式是完全不同的，具体体现在降雨（盐度变化）上，暖池区域显示盛冰期和全新世降雨差异不大，即这种冰期——间冰期时间尺度上主要受冰体积变化影响。而在“百年-千年”快速气候变化尺度上，暖池以及主流系特定区域主要表现在冷事件降雨增多而暖事件降雨减少，而南海及续流区的记录则显示冷事件降雨减少而暖事件降雨增多，体现出与东亚季风强弱变化谐变的特征。造成“暖池——主流系”不同区域记录的差异的机制很可能是水汽输送的模式不同。对于南海及主流及续流区域，由于主要受到东亚季风系统的影响，ITCZ 的移动，导致东亚季风的突变。在YD、H1冷事件期间，ITCZ 南移，夏季风减弱造成从赤道地区带来的高温热量和降水相对减少。而对于暖池影响区域而言，导致H1及YD冷事件期间降雨量显著增加的可能不是ITCZ的南向移动造成的雨带驻留，而很可能是此时的热带西太平洋的水热状态处于一种类ENSO的状态。我们的记录与北大西洋高纬度AMOC记录对比显示，AMOC的强弱变化很可能通过大洋温盐环流进而影响热带西太平洋在ENSO不同相态之间的转换，冷事件期间AMOC强度减弱，热带西太平洋暖池区处于一种类La Nina状态并进一步影响Walker环流和Hadley环流系统，从而造成区域降雨模式的改变。