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

该奖项支持一个项目，该项目旨在开发WAIS Divide冰芯(南极洲)捕获气体的高分辨率(20年)氮和氧同位素记录，并在GISP2(格陵兰岛)冰芯中建立一个用于年代学目的的比较记录。主要的科学目标是提供一个独立的南极洲西部过去10万年的温度变化记录，该记录不受经典的古温度计--冰同位素(18O和氘)固有的不确定性的影响。冰川冰中气泡中的氮同位素(Delta 15N)记录了由于多孔降雪层中空气的热分馏而导致的地表快速温度变化，当降雪变成冰时，这种同位素异常被记录在气泡中。利用这一基于气体的温度变化记录，结合作为极间地层标志的甲烷数据，拟议的工作将确定在海洋同位素阶段3(30-70KYR BP)和最后一次冰川终止期间千年尺度气候振荡期间格陵兰突然变暖和WAIS分水岭突然冷却的准确相对时间。氮同位素记录还提供了对过去降雪厚度的限制，这提供了来自冰芯的温度和积累率历史。将与WAIS的全新世分水岭(德尔塔北纬15度)一起寻找可能与太阳有关的周期。O2的氧同位素(Delta 18Oatm)是作为(Delta 15N)测量的副产品获得的。气体同位素记录将提高WAIS分水岭中其他大气气体测量的价值，预计这些测量将具有前所未有的质量。高分辨率(德尔塔180atm)记录将提供年代控制，供国际冰芯界使用，并用于地表冰川测年。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的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.