NOAA/WDS Paleoclimatology - Southwest Madagascar Coral Oxygen Isotope Data and SST Reconstruction from 1660-1994

The Agulhas Current (AC) is the strongest western boundary current in the Southern Hemisphere and is key for weather and climate patterns, both regionally and globally. Its heat transfer into both the midlatitude South Indian Ocean and South Atlantic is of global significance. A new composite coral record (Ifaty and Tulear massive Porites corals), is linked to historical AC sea surface temperature (SST) instrumental data, showing robust correlations. The composite coral SST data start in 1660 and comprise 200 years more than the AC instrumental record. Numerical modelling exhibits that this new coral derived SST record is representative for the wider core region of the AC. AC SSTs variabilities show distinct cooling through the Little Ice Age and warming during the late 18th, 19th and 20th century, with significant decadal variability superimposed. Furthermore, the AC SSTs are teleconnected with the broad southern Indian and Atlantic Oceans, showing that the AC system ! is pivotal for inter-ocean heat exchange south of Africa.

阿古拉斯海流（Agulhas Current, AC）是南半球最强的西边界流，对区域及全球尺度的天气与气候格局均具有关键影响。其向南印度洋中纬度海域与南大西洋的热量输送，具有全球重要意义。本研究构建的全新复合珊瑚记录（采自伊法蒂与图莱亚尔的块状滨珊瑚（Porites）），与历史阿古拉斯海流海表温度（Sea Surface Temperature, SST）仪器观测数据具有显著相关性。该复合珊瑚海表温度记录起始于1660年，较阿古拉斯海流的仪器观测记录多出200年的序列时长。数值模拟结果表明，这套基于珊瑚重建的海表温度记录可代表阿古拉斯海流更广范围的核心海域。阿古拉斯海流海表温度变率呈现出清晰的小冰期降温特征，以及18世纪末、19世纪与20世纪的升温趋势，同时叠加了显著的年代际变率信号。此外，阿古拉斯海流海表温度与南印度洋、南大西洋的大范围海域存在遥相关关系，表明阿古拉斯海流系统是非洲以南跨洋热量交换的关键枢纽。