Nitrogen and Oxygen Gas Isotopes in the WAIS Divide Ice Core as Constraints on Chronology, Temperature, and Accumulation Rate

severinghaus该奖项支持一个项目，该项目旨在开发WAIS Divide冰芯（南极洲）中被困气体的高分辨率（20年）氮和氧同位素记录，并与GISP2（格陵兰岛）冰芯中用于年代目的的比较记录。主要的科学目标是提供西南极洲过去10万年的独立温度变化记录，该记录不受冰同位素（18O和氘）固有的不确定性的影响，这是经典的古温度计。冰川冰气泡中的氮同位素δ 15N记录了多孔冰层中空气的热分馏导致的地表温度的快速变化，这种同位素异常在冰层结冰过程中被记录在气泡中。利用这种以气体为基础的温度变化记录，结合甲烷数据作为极间地层标志，本研究将确定在海洋同位素阶段3 （30-70 kyr BP）和末次冰期终止的千年尺度气候振荡期间，格陵兰岛突然变暖和WAIS分水岭地点突然变冷的精确相对时间。氮同位素记录还提供了对过去冰层厚度的限制，从而提供了冰芯的温度和积累速率历史。对可能与太阳相关的周期的搜索将通过WAIS划分全新世（Delta 15N）进行。O2的氧同位素（δ 18Oatm）作为（δ 15N）测量的副产物得到。气体同位素记录将提高WAIS分水岭其他大气气体测量的价值，预计其质量将达到前所未有的水平。高分辨率（Delta 18Oatm）记录将为国际冰芯社区和地表冰川冰定年提供时间控制。研究生的教育和实验室工作人员的培训将有助于国家的人力资源基础。将加强国际极地年范围内的外联活动。计划与巴黎大学LSCE实验室开展国际合作。

0538657SeveringhausThis award supports a project to develop high-resolution (20-yr) nitrogen and oxygen isotope records on trapped gases in the WAIS Divide ice core (Antarctica), with a comparison record for chronological purposes in the GISP2 (Greenland) ice core. The main scientific objective is to provide an independent temperature-change record for the past 100,000 years in West Antarctica that is not subject to the uncertainty inherent in ice isotopes (18O and deuterium), the classical paleothermometer. Nitrogen isotopes (Delta 15N) in air bubbles in glacial ice record rapid surface temperature change because of thermal fractionation of air in the porous firn layer, and this isotopic anomaly is recorded in bubbles as the firn becomes ice. Using this gas-based temperature-change record, in combination with methane data as interpolar stratigraphic markers, the proposed work will define the precise relative timing of abrupt warming in Greenland and abrupt cooling at the WAIS Divide site during the millennial-scale climatic oscillations of Marine Isotopic Stage 3 (30-70 kyr BP) and the last glacial termination. The nitrogen isotope record also provides constraints on past firn thickness, which inform temperature and accumulation rate histories from the ice core. A search for possible solar-related cycles will be conducted with the WAIS Divide Holocene (Delta 15N.) Oxygen isotopes of O2 (Delta 18Oatm) are obtained as a byproduct of the (Delta 15N) measurement. The gas-isotopic records will enhance the value of other atmospheric gas measurements in WAIS Divide, which are expected to be of unprecedented quality. The high-resolution (Delta 18Oatm) records will provide chronological control for use by the international ice coring community and for surface glacier ice dating. Education of a graduate student, and training of a staff member in the laboratory, will contribute to the nation's human resource base. Outreach activities in the context of the International Polar Year will be enhanced. International collaboration is planned with the laboratory of LSCE, University of Paris.