Lecture

Snow Physics and Hydrology: Introduction

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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 introduces the physics and hydrology of snow, covering topics such as the physical properties of snow, course information, textbooks, exercises, teaching style, the SNOWPACK model, learning objectives, the cryosphere, types of snow, effects of snow on the atmosphere, snow hydrology, the relevance and importance of snow, and its impact on freshwater resources. The instructor emphasizes the comprehensive understanding of snow physics, snow-atmosphere interaction, and snow modeling, highlighting the significance of snow in modifying energy and water fluxes, climate feedback, and water resource management.

Instructors (3)

Michael Lehning

Expertise Interaction Cryosphere - Atmosphere in particular Snow Processes Natural Hazards Warning and Forecasting Turbulence and Boundary Layer Flows over Alpine Terrain Mountain Hydrology and Permafrost Dynamics Renewable Energy (Wind and Solar) in the Alps and as Contribution to the Swiss Energy Change Agenda Expertise Interaction Cryosphere - Atmosphere in particular Snow Processes Natural Hazards Warning and Forecasting Turbulence and Boundary Layer Flows over Alpine Terrain Mountain Hydrology and Perm

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 (32)

Climate change feedback

Climate change feedbacks are effects of global warming that amplify or diminish the effect of forces that initially cause the warming. Positive feedbacks enhance global warming while negative feedbacks weaken it. Feedbacks are important in the understanding of climate change because they play an important part in determining the sensitivity of the climate to warming forces. Climate forcings and feedbacks together determine how much and how fast the climate changes.

Ice–albedo feedback

Ice–albedo feedback is a positive feedback climate process where a change in the area of ice caps, glaciers, and sea ice alters the albedo and surface temperature of a planet. Ice is very reflective, therefore it reflects far more solar energy back to space than the other types of land area or open water. Ice–albedo feedback plays an important role in global climate change. For instance, at higher latitudes, warmer temperatures melt the ice sheets.

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.

Water resource policy

Water resource policy, sometimes called water resource management or water management, encompasses the policy-making processes and legislation that affect the collection, preparation, use, disposal, and protection of water resources. Water is a necessity for all forms of life as well as industries on which humans are reliant, like technology development and agriculture. This global need for clean water access necessitates water resource policy to determine the means of supplying and protecting water resources.

Snowpack

Snowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for extended periods during the year. Snowpacks are an important water resource that feed streams and rivers as they melt. Therefore, snowpacks are both the drinking water source for many communities and a potential source of flooding (in case of sudden melting). Snowpacks also contribute mass to glaciers in their accumulation zone.

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