Mass and energy balance of snow and ice
|Convener: Willem Jan van de Berg | Co-Convener: Thomas Mölg|
The theme of this session is the mass and energy balance of snow and ice bodies (including debris-covered glaciers) in high-latitude and high-altitude regions. The response of snow covers, glaciers and ice sheets (Greenland, Antarctica) to meteorological and climatic forcing (in particular the global warming), their role within the climate system, and the generation of melt water resources and the influence on sea level define the scientific background for this session. In particular, the session targets on mass and energy exchange processes controlling spatial and temporal variations in surface melting and accumulation. Results from field studies, remote sensing analyses and numerical models of surface layer meteorology, surface energy fluxes, accumulation and ablation are within the scope of this session.
The unique physical properties of snow and ice largely control mass and energy exchange with the atmosphere. The radiation budget of these surfaces is completely different compared to any other terrestrial surface due to generally high albedo values, and the fact that snow and ice temperatures cannot exceed 0Â°C. This limit is also of relevance for sensible heat flux, often causing stable conditions in the surface layer prevailing during times of highest energy input. Katabatic flows, almost continuously present over tilted snow and ice surfaces, complicate the application of existing methods to quantify turbulent fluxes. The cooling influence of snow and ice bodies as well as the albedo feedback implies that the temperature response of the surface layer to a warmer climate is different than unity, which has consequences for downscaling of climate projections from global circulation models.
Surface mass and energy fluxes of snow and ice bodies are closely coupled with each other by melt and refreeze processes. The latter are difficult to quantify leading to uncertainties in the mass balance of glaciers and ice sheets. The need for improved methods for determining their mass and energy balance is further enhanced by the remoteness of many areas where they form important phenomena of the natural environment.