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.