Abstract
Snow refugia in snow-dominated Mediterranean climates are increasingly being recognized as key features that sustain summer streamflows, enhance soil moisture to promote ecosystem health, reduce wildfire hazards, and benefit snow-dependent species. Improved understanding of the processes that control patterns of snow refugia in complex terrain is needed to identify and conserve areas where refugia occur and to guide approaches to promote refugia. A spatially extensive investigation of snow disappearance date (SDD) indicated that isolated locations in lower elevations commonly associated with cold-air pools (CAPs) frequently functioned as snow refugia and that snow in these areas was especially sensitive to canopy cover. Snowpack dynamics at a selected snow refugium were simulated using a physically-based mass and energy balance snowmelt model to understand the specific processes that control variations in SDD between distinct landcover characteristics. Results indicate that the snow refugium associated with a canopy discontinuity accumulated 52% more snow water equivalent (SWE) than nearby sites under a dense canopy. Net energy flux in the refugium was slightly higher than sub-canopy locations, leading to a 20 day delay in SDD. Seasonal net turbulent energy fluxes were negative in both the refugium and dense forest, due to cold-air pooling and low wind speeds. Net snow cover energy flux was therefore dominated by net radiation and soil heat fluxes which indicate why these areas are more sensitive to canopy conditions relative to non-CAP locations where turbulent fluxes are likely to comprise a larger component of the snow cover energy balance.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)