Gap filling satellite snow cover for mountain catchments

Optical remote sensing offers the best combination of resolution, coverage and revisit times for monitoring mountain snow cover, but it is limited by cloud cover and topographic shading, and does not directly provide measures of snow mass essential for hydrological applications. Assimilation of snow cover products in snow models allows gap filling. In addition, the use of physically-based models allows rejection of misclassified changes in snow cover that are not energetically possible and hindcasting of snow mass consistent with energy required for observed snow cover depletion. This presentation will demonstrate assimilation of new European Space Agency snow_cci and AlpSnow snow cover products, which represent contributions to the International Network for Alpine Research Catchment Hydrology, using ensembles of perturbed simulations. Trade-offs between resolution, ensemble size, model complexity, accuracy and computational expense will be considered for well-defined seasonal snow cover in the Alps and a more challenging case study of ephemeral snow cover and frequent cloud cover in the Cairngorm Mountains of Scotland.