Firn Air Isotope and Temperature Measurements from Siple Dome and South Pole

Abstract: This data set includes d15N, d18O/2, dO2/N2/4, d40Ar/4, d38/Ar/2, d84Kr/48, and d132Xe/96 values for air drawn from the top 15 to 50 m of firn at the South Pole (summer and winter 1998) and a site at Siple Dome (summers 1996 and 1998). Data also include related firn temperature measurements. The objective of this research was to better understand thermal fractionation processes affecting records of atmospheric history from firn and ice core gases. Recent work (e.g., Severinghaus and Brook, 1999) has exploited trapped air in ice and deep firn as a record of past atmospheric composition and climate change. Interpretation of these paleoclimate archives is complicated by artifacts of thermal diffusion, a process in which heavier gases migrate down temperature gradients toward colder regions in the firn. Seasonal temperature change at the snow surface creates strong temperature gradients in the top few meters of the firn, which cause isotopic fractionation of firn gases. A specific goal of this research is to identify any long-term effects of seasonal temperature fluctuations on firn air isotopic anomalies.摘要：本数据集涵盖了取自南极点1998年夏、冬季以及锡普尔穹顶（Siple Dome）1996年与1998年夏季粒雪表层15至50米深度处的空气样品的d15N、d18O/2、dO2/N2/4、d40Ar/4、d38Ar/2、d84Kr/48及d132Xe/96同位素比值数据，同时包含配套的粒雪温度实测结果。 本研究的目标是深入理解影响粒雪与冰芯气体中古大气记录的热分馏过程。此前已有研究（如Severinghaus与Brook，1999）利用冰与深层粒雪中的封存空气作为重建过去大气成分与气候变化的代用记录。然而，热扩散效应所带来的人为干扰使得这些古气候档案的解译变得复杂：热扩散是指重质气体沿温度梯度向粒雪内更低温区域迁移的过程。雪面的季节性温度变化会在粒雪顶层数米范围内形成显著温度梯度，进而引发粒雪气体的同位素分馏。本研究的一项具体目标是探明季节性温度波动对粒雪空气同位素异常的长期影响。