NOAA/WDS Paleoclimatology - Cariaco Basin 2000-year seasonal Mg/Ca-SST Reconstruction

We present a high-resolution Mg/Ca reconstruction of tropical Atlantic sea surface temperatures (SSTs) spanning the last 2000?years using seasonally representative foraminifera from the Cariaco Basin. The range of summer/fall SST over this interval is restricted to 1.5°C, while winter/spring SST varies by 4.5°C over the same time period suggesting that boreal winter variations control interannual SST variability in the tropical North Atlantic. Antiphasing between the two data sets, including a large divergence in the seasonal records circa 900 Common Era, can be explained by changes in Atlantic meridional overturning circulation and associated changes in surface/subsurface temperatures in the tropical North Atlantic as well as resultant changes in trade wind belt location and intensity. A statistically significant but nonlinear relation exists between reconstructed winter/spring temperatures and solar variability.

本研究基于卡里亚科盆地（Cariaco Basin）中具有季节代表性的有孔虫（foraminifera），构建了覆盖过去2000年的热带大西洋海表温度（sea surface temperatures, SST）高分辨率镁钙比（Mg/Ca）重建序列。该时段内夏/秋季海表温度的变化范围仅为1.5℃，而冬/春季海表温度的波动幅度达4.5℃，这表明北半球冬季的温度变化主导了热带北大西洋的年际海表温度变率。两组数据集之间存在反相位关系，其中公元900年左右的季节记录出现显著分化，该现象可通过大西洋经向翻转环流（Atlantic meridional overturning circulation）的变化、热带北大西洋表层与次表层温度的相关改变，以及由此引发的信风带位置与强度变化得到合理解释。重建得到的冬/春季温度与太阳活动变率之间存在统计学意义显著但呈非线性的相关关系。