Sea surface temperature reconstruction for sediment core M35003-4 in the western tropical North Atlantic

Planktonic foraminiferal census counts are used to construct high-resolution sea surface temperature (SST) and subsurface (thermocline) temperature records at a core site in the Tobago Basin, Lesser Antilles. The record is used to document climatic variability at this tropical site in comparison to middle- and high-latitude sites and to test current concepts of cross-equatorial heat transports as a major player in interhemispheric climate variability. Temperatures are estimated using transfer function and modern analog techniques. Glacial - maximum cooling of 2.5°-3°C is indicated; maximum cooling by 4°C is inferred for isotope stage 3. The SST record displays millennial-scale variability with temperature jumps of up to 3°C and closely tracks the structure of ice-core Dansgaard/Oeschger cycles. SST variations in part of the record run opposite to the SST evolution at high northern latitude sites, pointing to thermohaline circulation and marine heat transport as an important factor driving SST in the tropical and high-latitude Atlantic, both on orbital and suborbital timescales.本研究以小安的列斯群岛多巴哥海盆的一处岩芯站位为研究对象，通过浮游有孔虫计数统计数据重建了高分辨率的海面温度（sea surface temperature, SST）与次表层（温跃层，thermocline）温度记录。该记录被用于刻画该热带站位的气候变率特征，并与中、高纬度站位的相关记录开展对比，同时检验当前将跨赤道热输送作为跨半球气候变率核心驱动因子的学术观点。温度估算采用传递函数（transfer function）与现代类比法（modern analog technique）完成。研究显示冰盛期存在2.5℃~3℃的最大降温幅度；同位素3期（isotope stage 3）的最大降温幅度则被推断为4℃。该海面温度记录呈现出千年尺度的气候变率，温度跃变幅度可达3℃，且与冰芯记录中的丹斯果-奥什格尔旋回（Dansgaard/Oeschger cycles）结构高度吻合。记录中部分时段的SST变化与北高纬度站位的SST演化趋势呈相反态势，这表明无论是在轨道尺度还是亚轨道时间尺度上，温盐环流（thermohaline circulation）与海洋热输送（marine heat transport）均为驱动热带与北大西洋高纬度海域海面温度变化的关键因素。