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Glacial-Interglacial Changes in Central Tropical Pacific Sea Surface Temperature

热带太平洋中部海面温度的冰期-间冰期变化

基本信息

批准号：
1502927
负责人：
Jean Lynch-Stieglitz
金额：
$ 30.99万
依托单位：
Georgia Tech Research Corporation
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-01 至 2019-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1502927&HistoricalAwards=false
关键词：
Glacial Interglacial Changes Central Tropical

项目摘要

Paleoclimate data sets can be used to help validate and improve the climate models that are used to predict future change. Of particular use have been data from the Last Glacial Maximum, a time with lowered atmospheric carbon dioxide, reasonably well understood forcing, and potentially broad data coverage. Accurate estimates of sea surface temperature are also essential if data from the geologic record is to be used to constrain equilibrium climate sensitivity -- defined as the global mean temperature response to a doubling of atmospheric carbon dioxide. Studies have shown that the connection between climate sensitivity and Last Glacial Maximum temperature is strongest in the tropics, where greenhouse gas forcing dominates the temperature signal. While Last Glacial Maximum temperature in the Western and Eastern Tropical Pacific is constrained by multiple sea surface temperature proxies, there is little existing data in the Central Tropical Pacific. Past estimates are highly uncertain and suggest little temperature change in this region, a result that is incompatible with reconstructions from climate models forced with Last Glacial Maximum boundary conditions. A series of sediment cores has recently been collected from the Line Islands Ridge in the Central Tropical Pacific, spanning a range of latitude from the equator to 7 degrees North. The PIs propose here to measure Mg/Ca ratios in surface dwelling planktonic foraminifera in order to reconstruct temperature changes over the last glacial cycle. Temperature reconstructions from cores collected over a range of latitude and water depth will help to assess the uncertainty in the new sea surface temperature estimates. Oxygen isotope ratios in surface dwelling planktonic foraminifera from the same set of sediment cores show an increased North-South gradient during glacial times. The PIs will use the Mg/Ca temperature proxy to determine if this corresponds to an increase in the North-South gradient in sea surface temperature. This data will be used to better understand how Tropical Pacific atmospheric and ocean circulation responded to glacial boundary conditions will aid in the understanding of the mechanisms for climate change in the tropics.The research team will make the data available to the climate modeling community, and the age model information and the inferences about the physical circulation generated as part of this project will serve as a useful base for other investigations using this set of sediment cores. Funding also supports education and mentoring of members of groups that are under-represented in science.

古气候数据集可用于帮助验证和改进用于预测未来变化的气候模式。特别有用的是末次盛冰期的数据，这是一个大气中二氧化碳含量较低的时期，对强迫有相当好的了解，并且可能有广泛的数据覆盖。如果要利用地质记录中的数据来约束平衡气候敏感性，对海洋表面温度的准确估计也至关重要。平衡气候敏感性的定义是全球平均温度对大气中二氧化碳增加一倍的反应。研究表明，气候敏感性与末次冰期最高温度之间的联系在热带地区最为明显，那里的温室气体强迫主导着温度信号。热带太平洋西部和东部的末次冰期最高温度受到多种海面温度代用指标的制约，而热带太平洋中部的现有数据很少。过去的估计高度不确定，表明该地区的温度变化不大，结果与末次盛冰期边界条件强迫的气候模式重建结果不相容。最近在热带太平洋中部的莱恩群岛海岭（Line Islands Ridge）收集了一系列沉积物岩心，范围从赤道到北纬7度。PIs在此建议测量地表浮游有孔虫的Mg/Ca比值，以重建末次冰期的温度变化。在纬度和水深范围内收集的岩心的温度重建将有助于评估新的海面温度估计的不确定性。来自同一组沉积物岩心的地表浮游有孔虫氧同位素比值显示，在冰期南北梯度增加。pi将使用Mg/Ca温度代理来确定这是否对应于海表面温度南北梯度的增加。这些数据将用于更好地了解热带太平洋大气和海洋环流如何对冰川边界条件作出反应，这将有助于了解热带气候变化的机制。研究小组将把这些数据提供给气候建模界，作为这个项目的一部分，年龄模型信息和对物理循环的推断将作为使用这组沉积物岩心进行其他调查的有用基础。资金还支持在科学领域代表性不足的群体成员的教育和指导。