Metamorphism of Polar Firn: Significance of Microstructure in Energy, Mass and Chemical Species Transfer

Energy, mass transfer and grain recrystallization processes show the most dynamic variation in the upper few meters of polar firn. Our understanding of processes in dry snow and polar firn shows feedback mechanisms exist between microstructure changes and energy and mass transfer coefficients. Differences between the predominant processes in the short polar summer and the winter cause sharp textural discontinuities in the stratigraphic columns at many polar locations. This distinctive layering forms the basis of studies on accumulation rates, layer ages and other investigations pertinent to firn and ice core analysis. Processes forming the stratification of the firn are not completely understood, nor are the associated loading patterns of chemical species. Past research on energy and mass transfer in near-surface polar firn is briefly surveyed. Current research focuses on processes controlled by the geometry of the ice and pore phases in the snow and firn. An overview is given of some of this work.