Energy balance at a cold Alpine firn saddle, Seserjoch, Monte Rosa

Little knowledge exists to date on the complex interactions between the atmosphere and glaciers leading to the formation of cold firn in high‐elevation accumulation areas in the Alps. Although the occurrence of cold firn and ice together is not a widespread phenomenon in the Alps, it is of particular significance as it relates to many glaciological issues, and has a major impact on glaciers in their role as an environmental and climatic archive. The atmospheric impact on cold firn was investigated using an energy balance study at the cold, 4300 m high firn saddle of Seserjoch, Monte Rosa area (Italy and Switzerland). Measurements of short‐ and longwave radiation, wind speed and wind direction, air temperature, humidity, snow height and snow and firn temperatures were conducted between September 1998 and August 2000 under difficult meteorological conditions. A 1 year time series of energy balance measurements spanning the period of May 1999 to April 2000 is presented. The results show that net radiation and turbulent heat fluxes are major elements of the energy balance. The heat fluxes due to surface melt in summer, and re‐freezing events (re‐freezing of meltwater at the surface, or rime accretion) cannot be neglected. The magnitude of these fluxes is difficult to interpret, as these are derived indirectly from the energy balance and, hence, also include instrumental and methodological errors in the energy balance calculation. Precise high‐resolution measurements of surface temperatures in summer made it possible to identify individual surface melt events and the prevailing meteorological conditions favouring or hindering surface melt. Copyright © 2004 Royal Meteorological Society