Reconstructions of paleoatmospheric H₂ using polar firn air and ice cores would lead to a better understanding of the H₂ biogeochemical cycle and how it is influenced by climate change and human activity. H₂ is a small, highly diffusive molecule, and its mobility in the ice matrix must be accounted for when intepreting polar firn air and ice core measurements. Previous work on the mobility of H₂ in ice has focused on warm (272-273 K), high pressure systems that are not directly comparable to conditions in polar ice sheets. In this study, the permeability, diffusivity, and solubility of H₂ are determined experimentally in ice Ih at temperatures relevant to polar ice sheets (199-253 K).

The data are reported as the optimized diffusivity (m² s^-1), solubility (mol m^-3 Pa^-1), and permeability (mol m^-1 s^-1 Pa^-1) for each of 17 experiments using two different samples of ice. Optimized values are reported with their ±1σ uncertainties. The temperature (K) for each experiment is also reported. 

This study was carried out using a “block degassing” method. This involves exposing a block of ice to a pure H₂ atmosphere for several hours, then replacing the H₂ with air and
monitoring the H₂ outgassing as a function of time. The measurements were analyzed using 3-dimensional finite difference diffusion model of the block of ice. The model diffusivity and solubility were varied across a wide range of possible values. Reported diffusivities and solubilities are the values which minimized the sum of the squared residuals between modeled and measured rates of H₂ outgassing. For more detailed methods, see Patterson & Saltzman (2021).