Argon and nitrogen isotope measurements in the Vostok ice core as aconstraint on phasing of CO2 and temperature changes

[125468 . severinghaus]该奖项支持对来自南极洲的Vostok冰芯气体同位素的持续测量。一个目标是确定二氧化碳变化和温度变化的阶段性，这可能会对假设的因果关系施加限制。在过去，由于气泡中的气体和周围冰之间存在巨大且不确定的年龄差异，对相位的识别一直受到阻碍。这项工作将通过采用气相温度指示器来避免这个问题。认为40Ar/39Ar是温度的一个定性指标，它与温度、堆积速率、层厚和气体同位素的重力分馏之间存在间接关系。该研究将对约200个末段II （130,000 yr B.P.）和末段IV （340,000 yr BP）冰盖样品进行氮和氩同位素测量。更广泛的影响可能包括更好地了解大气二氧化碳浓度在气候变化中的作用。

0125468SeveringhausThis award supports the continued measurements of gas isotopes in the Vostok ice core, from Antarctica. One objective is to identify the phasing of carbon dioxide variations and temperature variations, which may place constraints on hypothesized cause and effect relationships. Identification of phasing has in the past been hampered by the large and uncertain age difference between the gases trapped in air bubbles and the surrounding ice. This work will circumvent this issue by employing an indicator of temperature in the gas phase. It is argued that 40Ar/39Ar behaves as a qualitative indicator of temperature, via an indirect relationship between temperature, accumulation rate, firn thickness, and gravitational fractionation of the gas isotopes. The proposed research will make nitrogen and argon isotope measurements on ~ 200 samples of ice covering Termination II (130,000 yr B.P.) and Termination IV (340,000 yr BP). The broader impacts may include a better understanding of the role of atmospheric carbon dioxide concentrations in climate change.