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

该奖项支持在Byrd和simple Dome冰芯中捕获气体的高分辨率氮和氧同位素记录的发展，以及GISP2冰芯的全新世部分。这项工作的主要科学目标是了解到目前为止在15.3 ka和35 ka的简单圆顶记录中看到的神秘的d15N异常，并找到可能发生在两个岩芯中的其他事件。在这些事件中，被困空气的d15N接近于零，这意味着在冰形成时，固体层中的气体很少或没有重力分馏。这些事件可能代表低积累速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，因此可能揭示冰动力过程。在距离simple Dome 500公里的伯德地核中发现这些事件，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在附近的Byrd 18O/16O冰（d18Oice）记录中22 ka（在简单圆顶看到）突然变暖事件的令人困惑的缺失，并在Byrd d15N中寻找可能的相关信号。第三个目标利用了精确测量大气中O2的氧同位素组成（d18Oatm）的事实，这是d15N测量的副产品。拟议的气体同位素测量将支持一套完整的南极西部气候和大气气体记录，最终将包括WAIS Divide核心。这些记录将有助于将区域气候信号与全球气候信号区分开来，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，为国家的人力资源基础做出了贡献。教育和外联将是该项目的一个重要组成部分。

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.