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

该奖项支持开发关于伯德冰芯和西普穹顶冰芯以及GISP2冰芯全新世部分捕获气体的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记录的15.3ka和35ka的d15N神秘异常，并寻找可能在这两个核心发生的其他事件。在这些事件中，滞留空气的d15N接近零，这意味着冰层中的气体在形成冰的时候很少或没有重力分馏。这些事件可能代表了低积累速率和干旱的气象条件，因此可能包含了关于西南极气候历史的有价值的信息。或者，它们可能起源于裂隙，因此可能揭示了冰的动力过程。在距离Siple Dome 500公里的伯德地核发现这些事件，将对它们的起源和意义施加强有力的限制。第二个主要目标是探索附近的伯德18O/16O冰层(D18Oice)中令人费解的22ka(在Siple Dome)没有突然变暖事件，并在伯德d15N寻找可能的相关信号。第三个目标利用了这样一个事实，即作为d15N测量的副产品，获得了对大气O2氧同位素组成(D18Oatm)的精确测量。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，并可能对气候突然变化的原因施加限制。两名研究生的教育和实验室两名工作人员的培训，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.