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

印尼贯流(ITF)流是世界上唯一位于热带的主要洋流。它将地球上最大的热机--西太平洋暖池中大量温暖且盐度相对较低的海洋表面水域--的热量和含盐量异常传播到印度洋和更远的地方。因此，在调节东南亚、澳大利亚和非洲的海平面、气候和天气的季节性异常，影响到生物多样性生态系统和数百万人的生活方面，国际热带气旋的可变性有很大影响。然而，我们对ITF变异性的理解仅限于1984年的仪器观测记录，而且这些记录往往是不连续的。这些数据集使人们对最近的国际交易日基金的可变性与极端气候事件之间的联系有了基本的了解，如厄尔尼诺-南方涛动和印度洋偶极子。然而，由于记录如此之短，这些分析很难将人类强迫变化的部分与自然变异性分开。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世纪人类导致的气候变暖的反应做出自信预测的能力。迫切需要更长的ITF变异性记录。这个项目将改变我们对ITF变异性的理解。它将把ITF的温度和盐度记录从1984年延长到1770年，从而追溯到过去的工业化前时代。我们的分析将基于巨型珊瑚(Porites sp.)骷髅。这些珊瑚生活在ITF出口水域的“靶心”位置，位于澳大利亚西北部边缘，ITF温度和盐度异常最大，ITF控制明确(图1)。珊瑚岩芯已于2011年采集，并通过年度增长带计数(由项目合作伙伴Lough和Cantin计算)精确确定日期。我们的初步研究数据来自我们研究地点最年轻的珊瑚骨骼层，表明这些珊瑚忠实地记录了ITF温度和盐度异常(CFS，图2)。我们长达240年的ITF温度和盐度新记录将与数值海洋模式输出(项目伙伴英格兰和FANG参与)和公布的季风记录(例如来自澳大利亚、东南亚和非洲的树轮数据集)相结合，以彻底改变对ITF变异性及其气候学影响的理解。我们的项目将为我们了解东南印度洋与南亚-亚洲陆上气候之间的关系做出重大贡献，包括降雨、洪水、干旱和丛林大火。这对于让社会为气候变暖和南亚非洲季风区不断增加的人类足迹做好准备至关重要。

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.