The physical characteristics and CO2 concentrations of snow cover in the western Canadian arctic were examined at sites with different landscape forms (valley floor, hillslope, plateau). The greater exposure of plateau snow cover to blowing snow results in differences in the structure of the snow cover and different snow strata compared with snow covers on the other landscape forms. Both higher in-pack concentrations of CO2 and the largest vertical CO2 concentration gradients were found in plateau snow cover, the smallest in the deeper hillslope and valley snows. CO2 gradients in all landscape snow covers followed two patterns, i.e. where concentrations at the soil-snow interface are higher than those just below (5 cm) and the snow-atmosphere interface and vice versa. The latter pattern is due to the transport of the gas from the lower levels to the upper levels of the snowpack by wind-induced advection (windpumping) and is indicative of non steady-state, non-diffusive processes. These latter processes should thus be considered in any studies on CO2 fluxes from Arctic soil where snow cover topography and winds are conducive to windpumping and where concentration gradients resulting from diffusive processes have not been clearly identified.
