In situ and photographic measurements of avalanche crown transects

Despite its fundamental importance, crown depth is often treated as a scalar rather than a distributed variable in avalanche run-out and fracture models. To date, no studies have examined the distribution of depth across crown transects. We present results on geometry, depth distribution, and spatial correlation for transects along the crowns of small to large avalanches. Crown heights are fit well by normal or Weibull distributions and are spatially correlated. Transects are thinnest and decreasing toward the flanks, perhaps associated with fracture arrest. Underlying and adjacent terrain seems to have little influence on our transects. Instead, wind transported snow and upwind features play a dominant role. We suggest deposition of new snow by wind is a Gaussian process that drives transect shape. Comparing strength distributions and coefficients of variation from previous crown face studies, we suggest differences in overburden drive distributions of strength measured across crown faces.