Collaborative Research: Changing Holocene Environments of the Eastern Tropical Atlantic (CHEETA)

根据该奖项，项目研究员将对深海沉积物进行取样，以开发非洲西北部气候和植被以及热带大西洋SST和SST梯度变化的新全新世记录。 PI将进行为期28天的取芯巡航，以从沿着非洲西北部边缘（北纬35度至南纬10度）形成带状样带的高累积率地点采集一系列多岩心/重力岩心对。四个最有前途的核心将用于开发详细的（~40年分辨率）多代理记录全新世非洲气候和植被的变化，亚热带和热带大西洋上升流和SST。热带地区全新世气候变化的详细记录是罕见的，这一建议旨在填补这一观测空白。热带大西洋SST和非洲西北部气候与北大西洋SST在年际-数十年（和千年）时间尺度上的变化动态相关。认识到高纬度和低纬度大西洋气候之间的这些联系，研究计划建议探索全新世期间与高纬度冷却事件相关的热带海洋和非洲气候变化的特征，并建议开发植被变化的分子生物标志物记录（植物蜡和木质素衍生的酚）的气相色谱-质谱联用仪（GC/TOF-MS）监测全新世期间非洲植被的变化。还将利用陆源（风成）尘埃通量和粒度以及X射线荧光元素芯扫描重建非洲气候的变化。热带大西洋SST的全新世变化将重建这同一断面的核心使用烯酮，有孔虫Mg/Ca和稳定同位素，有孔虫普查计数测量。沿着样带的亚热带到热带热带SST变化将特别有助于追踪进入热带的百年尺度高纬度冷却事件，本项目的结果将最终用于确定这些热带气候、植被和SST信号之间的振幅和相位关系，以及与北大西洋气候已知变化的关系。这项研究的一个关键科学成果将是确定百年至千年时间尺度上热带大西洋气候变化的幅度，并了解它们在这些与社会相关的气候突变中的作用。

Under this award the PIs will core deep sea sediments that will develop new Holocene records of variations in NW African climate and vegetation and tropical Atlantic SSTs and SST gradients. The PIs will go on a 28-day coring cruise to recover a series of multicore/gravity core pairs from high accumulation rate sites forming a zonal transect along the NW African margin (35oN-10oS). Four of the most promising cores will be used to develop detailed (~40 year resolution) multiproxy records of Holocene variations in African climate and vegetation, and subtropical and tropical Atlantic upwelling and SSTs. Detailed records of Holocene climate variability from the tropics are rare and this proposal aims to fill this observational gap. Tropical Atlantic SSTs and NW African climate are dynamically linked to variations in North Atlantic SSTs at interannual-multidecadal (and millennial) timescales. Recognizing these linkages between high- and low-latitude Atlantic climate, the PIs propose to explore signatures of tropical ocean and African climate variability associated with high-latitude cooling events during the Holocene.The PIs propose to develop molecular biomarker records of vegetation change (plant waxes and lignin-derived phenols) by applying a new design of gas chromatograph-mass spectrometer (GC/TOF-MS) to monitor African vegetation shifts during the Holocene. Changes in African climate will be reconstructed also using terrigenous (eolian) dust fluxes and grain size, and XRF elemental core scanning. Holocene variations in tropical Atlantic SSTs will be reconstructed for this same transect of cores using alkenones, and foraminiferal Mg/Ca and stable isotopes, and foram census count measurements. Subtropical to tropical tropical SST changes along the transect will be particularly diagnostic for tracing the centuryscale high-latitude cooling events into the tropics.Results from this project will ultimately be used to define the amplitude and phasing relations of these tropical climate, vegetation, and SST signals relative to each other, and relative to known changes in North Atlantic climate. A key scientific dividend of this research will be to define the amplitudes of tropical Atlantic climate variability over centennial-millennial timescales, and to understand their role in these abrupt societally-relevant climate shifts.