Below that, diffusion through the pore space in the snow can cause slower chemical changes. Snow and firn are highly layered and the layering affects the transport processes. Snow and firn are highly layered because of differences in the way that the snow accumulates and because of aging. The stratigraphy notes the snow layering. Snow density and grain size give an indication of the type of snow.
Permeability is the parameter that controls how much air can flow through the pore space in snow.
The stratigraphy, density, permeability, and preservation of snow samples will be done in snow pits dug along the traverse. Once we have measured the properties of the snow and firn, we will use the measurements in our computer model that simulates the effects of air flow and diffusion in the snow, and try to determine whether there are differences in the transport processes at the different sites along the traverse. We will work with chemists to combine our modeling with chemical modeling to explain the observed changes in chemical concentrations. We will also try to develop a model to predict the way that snow changes over time as it is buried, a process called firnification. Snow and firn are highly layered porous media.