Noble Gases in the WAIS Divide Ice Core as Indicators of Local and Mean-ocean Temperature

WAIS 中的稀有气体将冰芯划分为当地和平均海洋温度的指标

• 批准号: 0944343
• 负责人: Jeffrey Severinghaus
• 金额: $ 46.25万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0944343&HistoricalAwards=false
• 关键词: Noble; Gases; WAIS; Divide; Ice

Severinghaus/0944343This award supports a project to develop both a record of past local temperature change at the WAIS Divide site, and past mean ocean temperature using solubility effects on atmospheric krypton and xenon. The two sets of products share some of the same measurements, because the local temperature is necessary to make corrections to krypton and xenon, and thus synergistically support each other. Further scientific synergy is obtained by the fact that the mean ocean temperature is constrained to vary rather slowly, on a 1000-yr timescale, due to the mixing time of the deep ocean. Thus rapid changes are not expected, and can be used to flag methodological problems if they appear in the krypton and xenon records. The mean ocean temperature record produced will have a temporal resolution of 500 years, and will cover the entire 3400 m length of the core. This record will be used to test hypotheses regarding the cause of atmospheric carbon dioxide (CO2) variations, including the notion that deep ocean stratification via a cold salty stagnant layer caused atmospheric CO2 drawdown during the last glacial period. The local surface temperature record that results will synergistically combine with independent borehole thermometry and water isotope records to produce a uniquely precise and accurate temperature history for Antarctica, on a par with the Greenland temperature histories. This history will be used to test hypotheses that the ?bipolar seesaw? is forced from the North Atlantic Ocean, which makes a specific prediction that the timing of Antarctic cooling should slightly lag abrupt Greenland warming. The WAIS Divide ice core is expected to be the premier atmospheric gas record of the past 100,000 years for the foreseeable future, and as such, making this set of high precision noble gas measurements adds value to the other gas records because they all share a common timescale and affect each other in terms of physical processes such as gravitational fractionation. Broader impact of the proposed work: The clarification of timing of atmospheric CO2 and Antarctic surface temperature, along with deep ocean temperature, will aid in efforts to understand the feedbacks among CO2, temperature, and ocean circulation. These feedbacks bear on the future response of the Earth System to anthropogenic forcing. A deeper understanding of the mechanism of deglaciation, and the role of atmospheric CO2, will go a long way towards clarifying a topic that has become quite confused in the public mind in the public debate over climate change. Elucidating the role of the bipolar seesaw in ending glaciations and triggering CO2 increases may also provide an important warning that this represents a potential positive feedback, not currently considered by IPCC. Education of one graduate student, and training of one technician, will add to the nation?s human resource base. Outreach activities will be enhanced and will to continue to entrain young people in discovery, and excitement will enhance the training of the next generation of scientists and educators.

Severinghaus/0944343该奖项支持一个项目，以开发在WAIS分水岭网站过去的本地温度变化的记录，以及过去的平均海洋温度使用大气氪和氙的溶解度效应。这两套产品共享一些相同的测量，因为本地温度是对氪和氙进行校正所必需的，因此相互协同支持。由于深海的混合时间，平均海洋温度在1000年的时间尺度上变化相当缓慢，这一事实进一步实现了科学上的协同作用。因此，快速的变化是不可能的，如果它们出现在氪和氙的记录中，可以用来标记方法上的问题。 产生的平均海洋温度记录将具有500年的时间分辨率，并将覆盖整个3400米长的核心。这一记录将被用来检验关于大气中二氧化碳变化原因的假设，包括在末次冰期期间，深海分层通过寒冷的含盐停滞层导致大气中二氧化碳下降的概念。由此产生的当地地表温度记录将与独立的钻孔温度测量和水同位素记录协同联合收割机，以产生与格陵兰温度历史相同的南极洲独特精确的温度历史。这段历史将被用来测试假设，？两极跷跷板来自北大西洋，这使得一个具体的预测，南极冷却的时间应该稍微滞后于格陵兰岛突然变暖。在可预见的未来，WAIS分水岭冰芯预计将成为过去10万年来最重要的大气气体记录，因此，进行这组高精度惰性气体测量为其他气体记录增加了价值，因为它们都有一个共同的时间尺度，并且在物理过程（如引力分馏）方面相互影响。拟议工作的更广泛影响：澄清大气CO2和南极表面温度的时间，沿着深海温度，将有助于理解CO2、温度和海洋环流之间的反馈。这些反馈关系到地球系统对人类强迫的未来响应。深入了解冰川消退的机制和大气中二氧化碳的作用，将大大有助于澄清在公众关于气候变化的辩论中公众头脑中相当混乱的一个话题。阐明两极跷跷板在结束冰川和触发二氧化碳增加方面的作用也可能提供一个重要的警告，即这是一个潜在的积极反馈，目前尚未被IPCC考虑。教育一名研究生，培训一名技术人员，会给国家带来什么？的人力资源基础。推广活动将得到加强，并将继续吸引年轻人参与发现，而兴奋将加强对下一代科学家和教育家的培训。