ACINN Graduate Seminar - SS 2024

2024-06-19 at 12:00 (on-line and on-site)

Snow-Atmosphere Interactions

Rebecca Mott-Grünewald

Research Unit Snow and Atmosphere, WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland

 

Mountain snow cover exhibits strong heterogeneity across various scales, largely influenced by intricate snow-atmosphere interactions. Recent experimental and modeling studies, which will be presented in this seminar shed light on these interactions, prompting the development of novel modeling strategies for snow-hydrological modeling. For the snow accumulation season, modeling strategies address the interaction between local flow fields, precipitation patterns, and snow redistribution. It was demonstrated that the local flow field at the ridge scale dictates precipitation patterns by advecting hydrometeors downwind of mountain ridges and peaks, significantly influencing snow distribution in mountain catchments. Two statistical downscaling schemes have been devised to efficiently downscale near-surface, low-resolution snowfall data to fine-scale snow deposition, accounting for preferential deposition in mountainous regions. Furthermore, the HICAR (High-resolution Intermediate Complexity Atmospheric Research) model was developed, dynamically downscaling meteorological fields to high resolutions by incorporating terrain-induced local flow fields with the precipitation field. The new model variant, HICARsnow, couples with the Factorial Snow Model 2 used variant (FSM2oshd) and a snow redistribution model, allowing for a comprehensive representation of complex snow-atmosphere interactions and feedback mechanisms. The seminar also addresses the impact of meteorological downscaling and process representation on snow-hydrological modeling during the accumulation and melting season. Various experiments demonstrate the high spatio-temporal variability of heat and momentum
fluxes over heterogeneous land surfaces, such as patchy snow covers or glaciers. High-resolution thermal infrared camera observations and multiple eddy-covariance sensors reveal turbulent temperature fluctuations, horizontal heat advection, stable internal boundary layer formation, and gust penetration through the stable internal boundary layer over patchy snow covers. Furthermore, results from a centimeter-resolution Large Eddy Simulation (LES) model, incorporating high-frequency Eddy Covariance (EC) data, illustrate the impact of intermittent warm air advection on temperature dynamics over melting snow under different wind scenarios.

 

 

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