Climate, Surface Energy Balance and Ground Thermal Regime at Three Arctic Sites (Spitsbergen, Siberia, Alaska)

We examine differences between three study sites located on Spitsbergen, in Alaska and in Siberia with respect to climate (air temperature, snow cover, net radiation), surface energy balance (evaporation, ground heat flux), surface characteristics and parent material. By comparing surface energy balance components of these three sites, the control mechanisms at the local scale (such as surface characteristics) are examined relative to the larger scale factors (such as climate). At all these sites, stations are installed on patterned ground: frost boils on Spitsbergen, low-centered polygons in Siberia and tussock tundra in Alaska. In addition to differences in surface characteristics and soil material, climatic conditions at the three sites are also different. The Lena Delta has the most continental climate (coldest winter air temperature and lowest precipitation), while Spitsbergen has a mild, maritime winter climate due to the influence of the Atlantic current. Continuous permafrost underlies all these sites. Though the sites on Spitsbergen and Alaska have different climates, the annual temperature at the top of the permafrost is similar (-3°C) however, the Alaskan summer is much warmer and the winter is much colder than Spitsbergen. The site in Siberia is underlain by cold permafrost with an annual surface permafrost temperature of -10°C. These climatic differences introduce important differences in the surface energy balance and ground thermal regime. Preliminary results of energy balance modeling show differences in snow ablation. Net radiation provides the major energy input for snow melt in Spitsbergen, while the snow ablation at Ivotuk is governed by atmospheric sensible heat. Almost 50 % of the total available energy during the snow ablation period at the Siberian site is lost to sublimation.