Articles | Volume 8, issue 12
Model description paper
08 Dec 2015
Model description paper |  | 08 Dec 2015

A factorial snowpack model (FSM 1.0)

R. Essery

Abstract. A model for the coupled mass and energy balances of snow on the ground requires representations of absorption of solar radiation by snow, heat conduction in snow, compaction of snow, transfer of heat to snow from the air and retention and refreezing of meltwater in snow. Many such models exist, but it has proven hard to relate their relative performances to the complexity of their process representations. This paper describes the systematic development of an open-source snowpack model with two levels of representation for each of the five processes mentioned above, allowing factorial experimental designs with 32 different model configurations. The model is demonstrated using driving and evaluation data recorded over one winter at an alpine site.

Short summary
Models of snow on the ground need to represent processes of solar radiation absorption, heat conduction, liquid water movement and compaction in snow and transfers of heat from the atmosphere. There are many such models in use, but their wide range in complexity makes it hard to understand how differences in process representations determine differences in predictions. Processes in the factorial snow model can be switched on or off independently, allowing highly controlled numerical experiments.