NOAA/WDS Paleoclimatology - Enggano Island, Indonesia Sub-fossil Coral Sr/Ca Record from 1824-1918 CE

Sea surface temperature (SST) variability in the south-eastern tropical Indian Ocean is crucial for rainfall variability in Indian Ocean rim countries. A large body of literature has focused on zonal variability associated with the Indian Ocean Dipole (IOD) which peaks in austral spring. In today’s climate, northward shifts of the Tropical Convergence Zone (TCZ) co-vary with the IOD, and it is unclear whether these shifts may also occur independently. We have developed a new monthly resolved SrCa record from a sub-fossil coral cored at Enggano Island (Sumatra, Indonesia). Core sections containing diagenetic phases are omitted from the SST reconstruction. UTh dating shows that the SrCa-based SST record extends from 1869–1918 and from 1824–1862 with a relative age uncertainty of ±3 years (2σ). At Enggano Island, coastal upwelling and cooling in austral spring impact SST seasonality and are coupled to the latitudinal position of the TCZ. The sub-fossil coral indicates an increase in SST seasonality between 1856 and 1918 relative to the 1930–2008 period. We attribute this to enhanced cooling due to stronger south-easterly (SE) winds driven by a northward shift in the TCZ in austral spring. A nearby sediment core indicates colder SSTs and a shallower thermocline prior to 1930. These results are consistent with an increase in the north–south SST gradient in the eastern Indian Ocean, calculated from historical temperature data, that is not seen in the zonal SST gradient. We conclude that the relationship between meridional and zonal variability in the eastern Indian Ocean is non-stationary and modulated by the long-term evolution of temperature gradients.

本归档古气候学研究数据集可通过美国国家海洋和大气管理局国家环境信息中心（NOAA National Centers for Environmental Information, NCEI）获取，该数据集隶属于古气候学世界数据服务中心（WDS）。该研究对应的NCEI研究分类为珊瑚（Coral）。数据集涵盖珊瑚与硬海绵（sclerosponges）的痕量金属相关参数，其地理覆盖范围为印度尼西亚地区。时间覆盖范围为无可用起始年份至无可用结束年份，单位为距今年份（BP）。如需了解参数与研究区位的详细信息，请查阅元数据文档。使用本数据集时，请引用本研究。