Snowpack structure and avalanching, Craigieburn Range, New Zealand

Abstract

Abstract A study of the seasonal development of the snowpack at 1700 m elevation in the Craigiebum Range, New Zealand, has revealed three phases of snowpack development. This phased development is considered in relation to snow avalanching. Analysis of a short period of continuous snowpack temperature gradient data has shown that temperature gradients exceed those generally required for recrystallisation processes, as evidenced by the common occurrence of temperature gradient forms in the snowpack. Partially metamorphosed new snow, especially clusters of rimed needles, and snow in the early stages of temperature gradient metamorphism, are weak in shear and frequently appear in avalanche sliding layers. Weak snowpack stratigraphies resemble those found for Northern Hemisphere inland-continental and coastal-maritime snow climates. Three categories of potential sliding layers for avalanche release are suggested. These are: (1) weaknesses in new snow stratigraphy, (2) weaknesses at old snow surfaces, and (3) ...