Colloque CEN 2024: Snow cover heterogeneity and its impact on the Climate and Carbon cycle of Arctic regions (SnowC2)
Abstract
One of the current limitations of the Canadian Land Surface Scheme including Biogeochemical Cycles (CLASSIC) is the use of a single-layer snow scheme, without an explicit parameterization for the snow cover fraction (SCF) and blowing snow sublimation losses. However, blowing snow sublimation losses are significant in the Arctic, and snowpacks are typically characterized by at least two distinct snow layers (e.g., a base depth hoar layer overlain by a wind slab), which have distinct physical characteristics. Moreover, the snow cover varies greatly at the typical scales from ~10-100 meters to larger-scale (>1 km) due to climatic and orographic gradients. As such, measuring and understanding snow cover heterogeneity, and representing it within process-based models represents one of the greatest ongoing challenges in atmospheric and hydrological sciences, which calls for innovative efforts to address this issue. This project aims to improve the representation of the simulated snow within CLASSIC in Arctic regions for more robust simulations of snow cover conditions and surface energy and carbon fluxes under current and future climates. To that purpose, a multilayer snowpack scheme will be implemented in CLASSIC, in addition to new SCF parameterizations, and blowing snow sublimation losses. SnowMIP in situ datasets will be used to carry these developments in addition to in situ stations along a Subarctic-Arctic gradient and the ESA Snow CCI products. The influence of these new developments will be then assessed against the evolution of the Snow CCI variables for different land types and for the simulated surface energy and carbon fluxes. CLASSIC will next be forced by an ensemble of climate projections from CMIP6, downscaled and bias-corrected to ERA5 to produce new improved land simulations over the whole Arctic region. Online (coupled) simulations within CanESM are also envisaged through future collaboration with Environment and Climate Change Canada.
