Ninth International Conference on Permafrost ... - IARC Research

Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s torientation may have strong effects on the measurements.These errors are magnified as measurements decrease invalue. Therefore, reflectivity data at periods of low sunangles must be considered with caution. The approximatedalbedo values are based on midday observations, occurringaround 12:00 (local time).Soil heat flux measurements along the transect displaymarginal differences within the daily average. Moresignificant are the differences in the diurnal heat fluxamplitude, which varies about 10–20 W/m² among theparticular locations. The polygonal centers and the crackdisplay more pronounced heat flux amplitudes compared tothe polygonal rims. This can be explained by differences inthermal diffusivity due to unlike soil moisture conditions.The varying heat capacities and conductivities lead to higherabsorption and re-release of energy at the wet locations.DiscussionThe different surface temperatures indicate variations inthe partition of the energy balance at the ground surface.This implies different contributions of sensible, latent, orground heat fluxes. The results display only slight variationsin ground heat fluxes among the different surface structures.Moreover, the comparatively small ground heat fluxes are ofsecondary importance within the complete energy balance.Thus, the energy partition at the ground surface primarilyaffects sensible and latent heat processes. Most likely at thedry polygon rims, more energy is available for sensible heatprocesses, while at the wet polygonal centers, the majorityof radiation is consumed through the evapotranspirationprocess.164