A Microstructural Dry Snow Metamorphism Model Applicable to Equi- Temperature and Temperature Gradient Environments

Abstract: Dry snow metamorphism has traditionally been classified by the thermal gradient encountered in the snowpack. Snow experiencing a predominantly equi-temperature environment develops different microstructure than snow that is subjected to a temperature gradient. As such, previous research has evaluated snow metamorphism based upon select thermal gradient dependent processes, when in reality, there is a continuum of physical processes simultaneously contributing to metamorphism. In previous research, a discrete temperature gradient transition between the two thermal environments has been used to activate separate morphological analyses. The cUrrent research focuses on a unifying approach to dry snow metamorphism that is applicable to generalized thermal environments. The movement ofheat and mass is not prescribed, but is allowed to develop naturally through modeling of physical processes. Equi-temperature, transition to kinetic growth, and kinetic growth are considered with this model. Density, grain size, bond size, and temperature dependencies are each examined in an equi-temperature metamorphism environment. The same physical model is then used to defme a smooth transition between equi-temperature and temperature gradient environments. Microstructural and environmental parameters that influence the transition to kinetic growth are examined. The correlation with established trends and experiments in each environment is excellent. The microstructural model is a new tool capable of evaluating metamorphism for a broad range ofmicrostructural parameters and thermal environments