Ogasawara winter Sr/Ca and U/Ca data of coral core OGA-02-1 and PDO reconstruction (coral-geoduck index)

The Pacific Decadal Oscillation (PDO), the leading mode of sea surface temperature (SST) anomalies in the extratropical North Pacific Ocean, has widespread impacts on precipitation in the Americas and marine fisheries in the North Pacific. However, marine proxy records with a temporal resolution that resolves interannual to interdecadal SST variability in the extratropical North Pacific are extremely rare. Here we demonstrate that the winter Sr/Ca and U/Ca records of an annually-banded reef coral from the Ogasawara Islands in the western subtropical North Pacific are significantly correlated with the instrumental winter PDO index over the last century. The reconstruction of the PDO is further improved by combining the coral data with an existing eastern mid-latitude North Pacific growth ring record of geoduck clams. The spatial correlations of this combined index with global climate fields suggest that SST proxy records from these locations provide potential for PDO reconstructions further back in time.

太平洋年代际振荡（Pacific Decadal Oscillation, PDO）是北太平洋温带海域海表温度（SST）异常的主导模态，其对美洲地区降水以及北太平洋海洋渔业均具有广泛影响。然而，当前具备可解析年际至年代际海表温度变率时间分辨率的北太平洋温带海域海洋代用记录却极为匮乏。本研究表明，采自北太平洋西部亚热带海域小笠原群岛的一株具有年纹层的礁珊瑚，其冬季Sr/Ca与U/Ca记录与近一个世纪以来的器测冬季PDO指数显著相关。通过将珊瑚数据与北太平洋中东部已有的象拔蚌（geoduck clams）生长纹记录相结合，PDO的重建结果得到进一步优化。该综合指数与全球气候场的空间相关性表明，来自上述海域的海表温度代用记录，可为回溯至更久远年代的PDO重建提供潜在可能。