IODP Exp 346: Onset and evolution of millennial-scale variability of the Asian monsoon (sailing participation)

亚洲季风是地球上对流最活跃的大气环流系统，其季节性降雨影响了世界上大约一半的人口。现代季风降雨的时间和分布是相对有据可查的，但亚洲季风过去的时空变化模式缺乏约束。最近的证据表明，东亚和印度的夏季风有显着的变化与Dansgaard-Oescgher（D-O）周期一致。这些周期具有全球性的共振，因为它们似乎通过大气、海洋、冰冻圈和生物圈之间的复杂相互作用在北方和南半球之间耦合。在一个典型的D-O循环中，北大西洋的缓慢冷却被以千年尺度重复的快速变暖突然终止。在D-O循环期间，收集地球气候响应的全面图片对于了解突然变暖事件如何通过气候系统放大和传播至关重要。最终，这一点很重要，因为北方高纬度地区D-O循环期间的温度上升率与未来几十年的预计变暖率相当。喜马拉雅和青藏高原（HTP）是地球上最具地形影响力的特征之一，在决定亚洲季风强度方面发挥着关键作用。此外，HTP的大小形成了阻挡低空西风急流环流（WJC）的障碍。地质记录暗示了青藏高原的隆升，始于公元前200年。5000万年前，在增强的大陆干旱，晚新生代冷却，亚洲夏季和冬季季风的加强，甚至可能导致增加风化和大气CO2的下降。此外，它已被提出，重新隆起和扩展的HTP在c。3.6 Ma是D-O型气候变率爆发的触发器。因此，季风变化和D-O周期之间的一致性被认为是在上新世更新世期间重新HTP隆起的结果，产生了两种离散的WSC模式。这两种大气环流模式的出现也为北大西洋记录的D-O事件提供了潜在的遥相关。综合大洋钻探计划（IODP）第346次考察计划在从日本海到中国东海北方的宽纬度范围内采集7个地点的岩心并进行测井，以检验上新世-更新世HTP的抬升以及随后出现的两种离散的WJC模式导致东亚夏季风和冬季风千年尺度变化放大的假设。IODP 346旨在回收将提供地质证据的岩心，以（1）监测WJC，EASM，EAWM和对马暖流的过去行为;（2）重建次极地锋和冰筏碎片的行为，以及（3）了解日本海的通风历史及其与通过对马海峡流入的淡水和冬季冷却的联系。

The Asian monsoon is the most convectively active atmospheric circulation system on Earth, and its seasonal rains impact about half the world's people. The timing and distribution of modern monsoon rainfall is relatively well documented, but past spatio-temporal patterns of changes in the Asian monsoon are poorly constrained. Recent evidence suggests the East Asian and Indian summer monsoons have varied significantly in concert with Dansgaard-Oescgher (D-O) cycles. These cycles have global resonance as they appear to be coupled between northern and southern hemispheres via complex interactions between the atmosphere, ocean, cyrosphere and biosphere. During a typical D-O cycle, slow cooling in the North Atlantic is terminated abruptly by rapid warming that recurs at a millennial-scale pacing. Assembling a comprehensive picture of Earth's climate response during D-O cycles is essential to understanding how abrupt warming events are amplified and propagated through the climate system. Ultimately this is important because the rate of temperature increase during a D-O cycle in northern high latitudes is comparable to rates of warming projected for the coming decades. The Himalaya and Tibetan Plateau (HTP), one of the most topographically imposing features on Earth, plays a key role in determining the strength of the Asian monsoon. In addition, the size of the HTP forms an obstacle that blocks low-level Westerly Jet circulation (WJC). Geological records have implicated the uplift of the Tibetan Plateau, starting c. 50 Myr ago, in enhanced continental aridity, late Cenozoic cooling, intensification of the Asian summer and winter monsoon, and even perhaps causing increased weathering and drawdown of atmospheric CO2. Furthermore, it has been proposed that the renewed uplift and extension of the HTP at c. 3.6 Ma acted as a trigger for the onset of D-O-type climatic variability. The coherence between monsoon variability and D-O cycles is therefore thought to be a consequence of renewed HTP uplift during the Plio-Pleistocene, creating two discrete modes of WSC. The emergence of these two modes of atmospheric circulation also provides a potential teleconnection to D-O events documented in the North Atlantic. Integrated Ocean Drilling Program (IODP) expedition 346 proposes to core and log seven sites covering a wide latitudinal range from the Japan Sea to the northern East China Sea to test the hypothesis that Plio-Pleistocene uplift of the HTP, and the consequent emergence of two discrete modes of WJC, caused the amplification of millennial-scale variability in the East Asian summer (EASM) and winter (EAWM) monsoons. IODP 346 aims to recover cores that will provide the geological evidence that (1) monitors past behaviours in the WJC, EASM, EAWM and the Tsushima Warm Current; (2) reconstructs the behaviour of the sub-Polar Front and ice-rafted debris, and (3) understands the ventilation history of the Japan Sea and its link to the influx of freshwater through the Tsushima Strait and winter cooling.