Snow surface temperature (T8) plays an important role in the formation of surface hoar or near-surface faceted crystals. The goal of this study was to obtain detailed information on T8 in different forest stands near the timberline. The investigations were conducted during clear nights and showed that the snow surface temperature is influeced very strongly by the forest canopy. While the air temperature was very similar on the different experimental sites, T8 was higher in the forest than in the open field; on the south-facing slope the difference between the forest and the open field was 3-4,5°C, and on the north-facing slope approximately 3-7°C. Taking into account that Epsilon-air is 0.7 and Epsilon-tree is 0.94, the incoming radiation (I) for the different experimental sites was calculated by the equation of Brunt (the canopy density was estimated using photographs taken with an 8 mm fish-eye). To calculate T8, air temperature and averaged values of the net radiation (because the net radiation (I) has only a small range of variation during clear nights) were used. The results show that the calcualted values were higher than the measured values (by approximately 2°C). However, a better correlation was found by using lower values of the emissivity (Epsilon-air 0.67 and Epsilon-tree 0.91).
