5 Conclusions

Based on a detailed examination of near-surface temperatures, moisture conditions, and radiation over 3 years, permafrost conditions were compared at two sloping sites with differing aspect in Beiluhe Basin to enrich permafrost degradation impacts observations in the hinterland of QTP. The results show that sunny and shady slope sites had similar air temperatures and precipitation amounts, but the difference in slope direction resulted in a difference in annual mean ground temperature of 1-2 °C. Higher ground surface temperatures at the sunny slope increased the difference between ground and air temperature (ΔTs), and caused deeper active layer thickness of ~1.0 m. Soil moisture content increased rapidly during the thawing of the active layer, but the higher ground surface temperature increased evaporation at the sunny site, making it much drier than the shady slope. The slope direction caused the downward shortwave radiation (DR) at the sunny slope to be greater than the shady slope, but there was higher net radiation at the shady slope due to differences in surface albedo. Nonetheless, the ground temperatures at the sunny slope were higher. The slope aspect also influenced the soil texture and SOM distribution. The data have improved knowledge on the ground surface boundary conditions in mountain permafrost regions, and indicate that sunny slopes may be >1-2 °C warmer than shady slopes when the permafrost distribution is similar. These results provide accurate information for permafrost degradation in high altitude permafrost areas.