WG 1: Physical Characterization of Snow Properties

Task 1.1: Identifying and assessing the essential snow variables (snow grain size, snow depth, snow density, snow covered area, snow temperature, thermal conductivity, albedo, full microstructure, snow impurity concentration): i.e., for which physical processes and applications the different snow variables are essential.

Task 1.2: Physical characterization of the essential snow variables: What are the relationships between the variables; How snow variables are affected by atmospheric thermodynamic and dynamic (wind drift) forcing; What are the response time scales of different snow variables?

Task 1.3: Snow network optimization, data quality control and homogenization: How much the essential snow variables vary in space during different seasons and over different environments (flat or mountainous, thin or thick snow pack, on different surface types: land, sea/lake ice, glacier). Spatial and temporal density of snow observations is also dependent on spatiotemporal variability of snow parameters and user needs; besides robust statistical methods for optimizing network density, the matching of ground-truth with satellite-based observations could further optimize networks. Network requirements and related challenges for different environments and user needs will be assessed. Methods for data quality control and homogenisation of snow series will be summarized from several projects at national or international level.

Task 1.4: Harmonization of snow observations in terms of the measured variables: snow observations are performed to support various user needs and thus are often non-standardized across disciplines. Hence, it is not straightforward to harmonise snow observations, and the first duty is to identify the problems that need to be solved, and to evaluate the possible drawbacks from harmonization. Practical and organizational actions needed for the harmonization will be assessed. Further, the Action will quantify the potential benefits generated from a harmonized network of snow observations for network operators and data users.

WG1 is connected to WG2 with regards to techniques applied for measurement of the essential snow variables and to WG3 with regards to the physical characterization of the modelled snow variables.