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

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.