Snowfall, snow metamorphism, firn compaction, runoff, and refreezing are all fundamental glaciological processes. Accurate models of these processes, and observations to calibrate those models, are essential for many applications including the conversion of satellite altimetry data into ice mass, estimating the meltwater storage capacity of firn and glacier ice, modeling surface energy balance, and interpreting ice-core paleoclimate records, among others. This session brings together both observational and modeling studies that advance our understanding of the physical processes of snow, firn, and glacier ice. We invite contributions from all aspects of these research topics and particularly welcome studies of i) advances in observational methods, ii) remote sensing of snow and firn, iii) model assessments, iv) development of physics-based firn and surface mass balance (SMB) models, and v) applications of firn and SMB models to glaciological problems. We also welcome presentations describing open-science contributions to the snow and firn community.