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Lecture

Drifting Snow Sublimation: Modeling and Field Results

In course

ENV-525: Physics and hydrology of snow

This course covers principles of snow physics, snow hydrology, snow-atmosphere interaction, and snow modeling. It transmits detailed understanding of physical processes within the snow and at its interfaces with the atmosphere and the ground, and presents ...

Description

This lecture covers the process of drifting snow sublimation, including its importance in Arctic and Tundra environments, sublimation modeling, suspension dynamics, and field measurement results. It discusses the impact on mass balance, moisture mass balance, and the spatial distribution of sublimation. The lecture also presents comparisons to surface sublimation, the effect on total mass balance, and the spatial heterogeneity of drifting snow sublimation. Various factors affecting sublimation, such as temperature, moisture, and concentration, are analyzed through field data and models.

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Instructors (3)

Michael Lehning

Wolf Hendrik Huwald

Dr. Hendrik Huwald is a scientist at the Laboratory of Cryospheric Sciences (CRYOS) and a lecturer at the Environmental Sciences and Engineering Section (SSIE) of the Swiss Federal Institute of Technology in Lausanne (EPFL). He completed his PhD in 2003 at the Swiss Federal Institute of Technology in Zürich (ETHZ), developing a numerical model for sea ice and studying energy transfer processes in the Arctic. Between 2005 and 2012 he was a post-doctoral fellow and scientist at the Laboratory of Environmental Fluid Mechanics and Hydrology (EFLUM) of EPFL working on Alpine snow-atmosphere interaction, and energy balance-related research mainly in mountain regions. During this time, he designed, led and participated in numerous large field experiments in different environments. In 2013 he joined the newly founded CRYOS laboratory where he conducted research in the domains of snow science, hydrology, boundary layer meteorology and environmental sensing. He has extensive experience with project management both on national and international level.

Johan Alexandre Philippe Gaume

I started my scientific career in 2008 at the Grenoble University in the IRSTEA laboratory where I did my master's thesis on the rheology of dense granular materials using the discrete element method. In the same lab, I followed with a PhD on the numerical modeling of the release depth of extreme avalanches using a combined mechanical-statistical approach and spatial extreme statistics. In 2013 I obtained a postdoc position at the WSL Institute for Snow and Avalanche Research SLF in Davos where I was in charge of developing and applying numerical models to improve the evaluation of avalanche release conditions and thus avalanche forecasting. While my PhD was mostly theoretical and numerical, my postdoc in Davos allowed me to gain a practical expertise by participating in laboratory and field experiments which helped to validate the models I develop. In 2016, I was awarded a SNF grant to work as a research and teaching associate in CRYOS at EPFL on the multiscale modeling of snow and avalanche processes. I developed discrete approaches to model snow micro-structure deformation and failure in order to evaluate constitutive snow models to be used at a larger scale in continuum models. I also developed numerical models for wind-driven snow transport. In 2017, I was a Visiting Scholar at UCLA to work on a Material Point Method (MPM) to simulate both the initiation and propagation of snow avalanches in a unified manner. The UCLA MPM model was initially developed for the Disney movie "Frozen" and has been modified and enriched based on Critical State Soil Mechanics to model the release and flow of slab avalanches. The results of this collaboration have been published in Nature Communications. In 2018, I was awarded the SNF Eccellenza Professorial Fellowship and became professor at EPFL and head of SLAB, the Snow and Avalanche Simulation Laboratory. At SLAB, we study micro-mechanical failure and fracture propagation of porous brittle solids, with applications in snow slab avalanche release. We also simulate avalanche dynamics and flow regime transitions over complex 3D terrain through the development of new models (depth-resolved and depth-averaged) based on MPM.In 2020, I obtained a SPARK grant to develop a new approach to simulate and better understand complex process chains in gravitational mass movements, including permafrost instabilities, rock, snow and ice avalanches and transitions to debris flows.

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Related concepts (18)

Snow

Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away.

Temperature

Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called centigrade), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes.

Spatial analysis

Spatial analysis is any of the formal techniques which studies entities using their topological, geometric, or geographic properties. Spatial analysis includes a variety of techniques using different analytic approaches, especially spatial statistics. It may be applied in fields as diverse as astronomy, with its studies of the placement of galaxies in the cosmos, or to chip fabrication engineering, with its use of "place and route" algorithms to build complex wiring structures.

Hydrosphere

The hydrosphere () is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Although Earth's hydrosphere has been around for about 4 billion years, it continues to change in shape. This is caused by seafloor spreading and continental drift, which rearranges the land and ocean. It has been estimated that there are 1.386 billion cubic kilometres (333 million cubic miles) of water on Earth.

Ice

Ice is water frozen into a solid state, typically forming at or below temperatures of 32 °F, 0 °C, or 273.15 K. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects. Beyond the Solar System, it occurs as interstellar ice.

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