Subtropical coral reveals abrupt early-twentieth-century freshening in the western North Pacific Ocean
Subtropical coral reveals abrupt early-twentieth-century freshening in the western North Pacific Ocean
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DOI：
10.1130/g25581a.1
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发表时间：
2009-06-01
期刊：
影响因子：
5.8
通讯作者：
Kawahata, Hodaka
中科院分区：
文献类型：
--
作者：
Felis, Thomas;Suzuki, Atsushi;Kawahata, Hodaka
仪器气候观测提供了二十世纪全球陆地和海洋温度的可靠记录。与温度不同，1970 年之前对表层海洋盐度的连续观测很少，而且 20 世纪盐度变化的幅度在很大程度上是未知的。表层海洋盐度是气候动态的主要组成部分，因为它影响海洋环流和水团形成。在这里，我们根据小笠原群岛珊瑚中的 Delta O-18、Sr/Ca 和 U/Ca 的双月记录，展示了自 1873 年以来西亚热带北太平洋表层水域盐度变化的年度重建。重建结果表明，1905 年至 1910 年间，海洋表面条件发生了突然的转变。大气观测数据表明，这种突然的清新与驱动黑潮系统和相关副热带环流的风的减弱有关。我们注意到，二十世纪初北太平洋西副热带地区突然出现的气候变化早于北大西洋北部气候突然变化的几年。在未来几十年的气候预测中，应考虑表层海洋盐度突然发生变化的可能性。
Instrumental climate observations provide robust records of global land and ocean temperatures during the twentieth century. Unlike for temperature, continuous salinity observations in the surface ocean are scarce prior to 1970, and the magnitude of salinity changes during the twentieth century is largely unknown. Surface ocean salinity is a major component in climate dynamics, as it influences ocean circulation and water mass formation. Here we present an annually resolved reconstruction of salinity variations in the surface waters of the western subtropical North Pacific Ocean since 1873, based on bimonthly records of delta O-18, Sr/Ca, and U/Ca in a coral from the Ogasawara Islands. The reconstruction indicates that an abrupt regime shift toward fresher surface ocean conditions occurred between 1905 and 1910. Observational atmospheric data suggest that the abrupt freshening was associated with a weakening of the winds that drive the Kuroshio Current system and the associated subtropical gyre circulation. We note that the abrupt early-twentieth-century freshening in the western subtropical North Pacific precedes abrupt climate change in the northern North Atlantic by a few years. The potential for abrupt regime shifts in surface ocean salinity should be considered in climate predictions for the coming decades.