Nitrogen and oxygen gas isotopes in the Siple Dome and Byrd ice cores

Siple Dome 和 Byrd 冰芯中的氮气和氧气同位素

• 批准号: 0440975
• 负责人: Jeffrey Severinghaus
• 金额: $ 26.31万
• 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: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0440975&HistoricalAwards=false
• 关键词: Nitrogen; oxygen; gas; isotopes; Siple

The award supports the development of high-resolution nitrogen and oxygen isotope records on trapped gases in the Byrd and Siple Dome ice cores, and the Holocene part of the GISP2 ice core. The primary scientific goals of this work are to understand the enigmatic d15N anomalies seen thus far in the Siple Dome record at 15.3 ka and 35 ka, and to find other events that may occur in both cores. At these events, d15N of trapped air approaches zero, implying little or no gravitational fractionation of gases in the firn layer at the time of formation of the ice. These events may represent times of low accumulation rate and arid meteorological conditions, and thus may contain valuable information about the climatic history of West Antarctica. Alternatively, they may stem from crevassing and thus may reveal ice-dynamical processes. Finding the events in the Byrd core, which is located 500 km from Siple Dome, would place powerful constraints on their origin and significance. A second major goal is to explore the puzzling absence of the abrupt warming event at 22 ka (seen at Siple Dome) in the nearby Byrd 18O/16O record in the ice (d18Oice), and search for a possible correlative signal in Byrd d15N. A third goal takes advantage of the fact that precise measurements of the oxygen isotopic composition of atmospheric O2 (d18Oatm) are obtained as a byproduct of the d15N measurement. The proposed gas-isotopic measurements will underpin an integrated suite of West Antarctic climate and atmospheric gas records, which will ultimately include the WAIS Divide core. These records will help separate regional from global climate signals, and may place constraints on the cause of abrupt climate change. Education of two graduate students, and training of two staff members in the laboratory, contribute to the nation's human resource base. Education and outreach will be an important component of the project.

该奖项支持在Byrd和Siple Dome冰芯以及GISP 2冰芯的全新世部分中开发高分辨率氮和氧同位素记录。 这项工作的主要科学目标是了解迄今为止在Siple Dome记录中在15.3 ka和35 ka发现的神秘的d15 N异常，并找到可能发生在两个核心中的其他事件。 在这些事件中，被困空气的d15 N接近于零，这意味着在冰形成时，积雪层中的气体很少或没有重力分馏。 这些事件可能代表了低积累率和干旱气象条件的时期，因此可能包含有关西南极洲气候历史的宝贵信息。 或者，它们可能源于裂缝，从而可能揭示冰动力学过程。 在距离Siple Dome 500公里的Byrd核心中找到这些事件，将对它们的起源和意义产生强有力的限制。 第二个主要目标是探索令人费解的缺席的突然变暖事件在22 ka（看到在Siple圆顶）在附近的伯德18 O/16 O记录在冰（d18 Oice），并寻找一个可能的相关信号伯德d15 N。 第三个目标利用了这样一个事实，即大气O2的氧同位素组成（d18 Oatm）的精确测量是作为d15 N测量的副产品获得的。 拟议的气体同位素测量将支持一套完整的西南极气候和大气气体记录，其中最终将包括WAIS分水岭核心。 这些记录将有助于区分区域和全球气候信号，并可能限制气候突变的原因。 两名研究生的教育和两名实验室工作人员的培训有助于国家的人力资源基础。 教育和外联将是该项目的一个重要组成部分。