Quantitative measurements of snow properties are essential to understand snow metamorphism, the formation of natural hazards and all components of the radiation balance (albedo, microwave brightness temperature and backscatter, mass and heat transfer) and their impact on climate, as well as the interaction of the snowpack with its environment. The past 10 years have seen a rapid development of new techniques beyond the traditional methods described in Fierz et al. (2009), International Classification for Seasonal Snow on the Ground. Results from three workshops held in 2013 and 2014 (IACS Snow Grain Size Workshop – Measurements and Applications, April 2013, Grenoble, France; Intercomparison of Snow Grain Size Measurements Workshop, March 2014, Davos, Switzerland, and August 2014, Reading, UK) built the foundation for this special issue. Goals of the workshops included proposing a more precise definition of "snow grain size" and the possible substitution of this term with "specific surface area" for its use in quantitative applications, and the comparison of direct and indirect methods of measuring snow "grain size" including the following: micro-tomography, BET adsorption method, casting methods, spectroscopic methods (e.g. using 1030nm absorption feature), near-infrared photography, direct optical methods (e.g. based on 1310nm reflectance), high-resolution penetrometry (e.g. SnowMicroPen), traditional grain size observation and macroscopic grain size photography. Other variables characterizing the snow microstructure (density, thermal conductivity, others) are also concerned.

The goal of this special issue is to build an evolving volume of refereed and high-quality contributions to snow measurement methods and quantitative snow characterization. Such a volume will serve as a unique open reference to the fast-evolving field in snow measurement techniques and snow microstructure characterization.

This special issue invites submissions reporting on results obtained in these workshops and beyond, also including studies relevant to the objective of this special issue but carried out independently.