Transforming our understanding of the Indonesian Throughflow variability and its climatological influence, long coral records from strategic sites

印度尼西亚洋流是世界上唯一位于热带的主要洋流。它将热量和含盐量的异常从地球最大的热力发动机-西太平洋暖池的大量温暖和相对低盐度的海洋表面沃茨-传播到印度洋和更远的地方。因此，ITF的变异性与调节东南亚、澳大利亚和非洲季节性的海平面、气候和天气异常密切相关，影响着生物多样性生态系统和数百万人的生活。然而，我们对ITF变化的理解仅限于可追溯到1984年的仪器观测记录，并且这些记录通常是不连续的。这些数据集使人们基本了解了最近国际热带气旋变化与厄尔尼诺-南方涛动和印度洋偶极子等极端气候事件之间的联系。然而，由于记录如此之短，这些分析很难从自然变异中分离出气候变化的强迫成分。这个问题严重限制了我们对ITF以及亚洲、澳大利亚和非洲季风对21世纪世纪人类引起的变暖的反应做出可靠预测的能力。我们迫切需要更长时间的ITF变异性记录。这个项目将改变我们对ITF变异性的理解。通过将ITF温度和盐度记录从1984年延长到1770年，它将追溯到过去的工业化前时代。我们的分析将基于巨型珊瑚（滨珊瑚属）的化学性质。骷髅这些珊瑚生活在ITF出口沃茨的“靶心”位置，位于澳大利亚西北部边缘，ITF温度和ITF盐度异常最大，ITF控制明确（CfS，图1）。珊瑚核心已经在2011年收集，并通过年度生长带计数（由项目合作伙伴Lough和Cantin）精确确定日期。我们的初步研究数据来自我们研究地点的珊瑚骨骼的最年轻层，表明这些珊瑚忠实地记录了ITF温度和盐度异常（CfS，图2）。我们新的240年ITF温度和盐度记录将与数值海洋模型输出（项目合作伙伴England和Feng的参与）和已发表的季风记录（例如，澳大利亚、东南亚和非洲的树木年轮数据集），以彻底改变对ITF变率及其气候影响的理解。我们的项目将为我们对印度洋东南部与澳大利亚近海气候（包括降雨、洪水、干旱和林火）之间关系的认识做出逐步变化的贡献。这对于使社会做好准备应对气候变暖和人类在澳亚非季风区不断增加的足迹至关重要。

The Indonesian Throughflow (ITF) current is the world's only major oceanic current situated in the tropics. It propagates heat and salt-content anomalies from the Earth's largest heat engine, the vast mass of warm and relatively low-salinity ocean surface waters of the Western Pacific Warm Pool, into the Indian Ocean and beyond. ITF variability is, therefore, deeply implicated in modulating sea-level-, climate- and weather-anomalies seasonally over southeast Asia, Australia and Africa, affecting biodiverse ecosystems and the lives of millions of people. However, our understanding of ITF variability is limited to instrumented observational records that date back to only 1984, and these records are often discontinuous. These data sets provide a basic understanding of the linkages between very recent ITF variability and extreme climate events such as the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). However, because the record is so short, these analyses struggle to isolate the anthropogenically-forced component of change from natural variability. This problem severely limits our ability to make confident predictions of the response of the ITF and the Asian, Australian and African monsoons to 21st century human-induced warming. Longer records of ITF-variability are desperately needed.This project will transform our understanding of ITF variability. It will reach back into the past to pre-industrial times by extending the records of ITF temperature and salinity from 1984 to 1770. Our analysis will be based on the chemistry of giant coral (Porites sp.) skeletons. These corals live in a "bulls-eye" location for ITF outlet waters, on the Northwest Australian margin where ITF-temperature and ITF-salinity anomalies are greatest and ITF-control is unequivocal (CfS, Fig. 1). The coral cores were already collected in 2011 and precisely dated by annual growth band counting (by Project Partners Lough and Cantin). Our pilot study data from the youngest layers of the coral skeletons from our study site demonstrate that these corals faithfully record ITF-temperature and -salinity anomalies (CfS, Fig. 2). Our new 240 year-long record of ITF temperature and salinity will be combined with numerical ocean model outputs (involvement of Project Partners England and Feng) and published monsoon records (e.g., tree-ring data sets from Australia, South East Asia and Africa) to revolutionise understanding of ITF-variability and its climatological influence.Our project will make a step-change contribution to our knowledge of the relationship between south-eastern Indian Ocean and onshore-offshore Austral-Asian climate, including rainfall, floods, drought and bushfires. This is vital for preparing societies for a warming climate and an ever-increasing human footprint in the Austral-Asian-African monsoon regions.