Paleoatmospheric Krypton and Xenon Abundances from Trapped Air in Polar Ice as Indicators of Past Mean Ocean Temperature

极地冰中滞留空气中的古大气氪和氙丰度作为过去平均海洋温度的指标

• 批准号: 0538630
• 负责人: Jeffrey Severinghaus
• 金额: $ 32.59万
• 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: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538630&HistoricalAwards=false
• 关键词: Paleoatmospheric; Krypton; Xenon; Abundances; Trapped

0538630SeveringhausThis award supports a project to produce the first record of Kr/N2 in the paleo-atmosphere as measured in air bubbles trapped in ice cores. These measurements may be indicative of past variations in mean ocean temperature. Knowing the mean ocean temperature in the past will give insight into past variations in deep ocean temperature, which remain poorly understood. Deep ocean temperature variations are important for understanding the mechanisms of climate change. Krypton is highly soluble in water, and its solubility varies with temperature, with higher solubilities at colder water temperatures. A colder ocean during the last glacial period would therefore hold more krypton than today's ocean. Because the total amount of krypton in the ocean-atmosphere system is constant, the increase in the krypton inventory in the glacial ocean should cause a resultant decrease in the atmospheric inventory of krypton. The primary goal of this work is to develop the use of Kr/N2 as an indicator of paleo-oceanic mean temperature. This will involve improving the analytical technique for the Kr/N2 measurement itself, and measuring the Kr/N2 in air bubbles in ice from the last glacial maximum (LGM) and the late Holocene in the Vostok and GISP2 ice cores. This provides an estimate of LGM mean ocean temperature change, and allows for a comparison between previous estimates of deep ocean temperature during the LGM. The Vostok ice core is ideal for this purpose because of the absence of melt layers, which compromise the krypton and xenon signal. Another goal is to improve precision on the Xe/N2 measurement, which could serve as a second, independent proxy of ocean temperature change. A mean ocean temperature time series during this transition may help to explain these observations. Additionally, the proposed work will measure the Kr/N2 from marine isotope stage (MIS) 3 in the GISP2 ice core. Knowing the past ocean temperature during MIS 3 will help to constrain sea level estimates during this time period. The broader impacts of the proposed work: are that it will provide the first estimate of the extent and timing of mean ocean temperature change in the past. This will help to constrain previously proposed mechanisms of climate change involving large changes in deep ocean temperature. This project will also support the education of a graduate student. The PI gives interviews and talks to the media and public about climate change, and the work will enhance these outreach activities. Finally, the work will occur during the International Polar Year (IPY), and will underscore the unique importance of the polar regions for understanding the global atmosphere and ocean system.

0538630Severinghaus 该奖项支持一个项目，该项目通过测量冰芯中捕获的气泡来产生古大气中 Kr/N2 的第一个记录。这些测量结果可能表明过去平均海洋温度的变化。了解过去的平均海洋温度将有助于深入了解过去深海温度的变化，但人们对此仍知之甚少。深海温度变化对于理解气候变化机制非常重要。 氪极易溶于水，其溶解度随温度变化，水温较低时溶解度较高。因此，末次冰期期间较冷的海洋比今天的海洋含有更多的氪。由于海洋-大气系统中氪的总量是恒定的，冰川海洋中氪库存的增加应该导致大气中氪库存的减少。这项工作的主要目标是开发利用 Kr/N2 作为古海洋平均温度的指标。这将涉及改进 Kr/N2 测量本身的分析技术，以及测量末次盛冰期 (LGM) 和全新世晚期 Vostok 和 GISP2 冰芯中冰中气泡中的 Kr/N2。这提供了末次盛冰期平均海洋温度变化的估计，并允许对末次盛冰期期间深海温度的先前估计进行比较。东方冰芯非常适合此目的，因为它不存在会损害氪和氙信号的融化层。另一个目标是提高 Xe/N2 测量的精度，它可以作为海洋温度变化的第二个独立指标。这一转变期间的平均海洋温度时间序列可能有助于解释这些观察结果。此外，拟议的工作将测量 GISP2 冰芯中海洋同位素阶段 (MIS) 3 的 Kr/N2。了解 MIS 3 期间过去的海洋温度将有助于限制该时间段内的海平面估计。拟议工作的更广泛影响是：它将提供对过去平均海洋温度变化的程度和时间的首次估计。这将有助于限制先前提出的涉及深海温度大幅变化的气候变化机制。该项目还将支持研究生的教育。首席研究员就气候变化问题向媒体和公众进行采访和演讲，这项工作将加强这些外展活动。最后，这项工作将在国际极地年（IPY）期间进行，并将强调极地地区对于了解全球大气和海洋系统的独特重要性。