Air and near-surface ground temperatures were measured using dataloggers over 14 years (2006-2020) in 10 locations at 2262 to 2471 m.a.s.l. in a glacial cirque of the Cantabrian Mountains. These sites exhibit relevant differences in terms of substrate, solar radiation, orientation, and geomorphology. Basal temperature of snow (BTS) measurements and electrical resistivity tomography of the talus slope were also performed. The mean annual near-surface ground temperatures ranged from 5.1 degrees C on the sunny slope to 0.2 degrees C in the rock glacier furrow, while the mean annual air temperature was 2.5 degrees C. Snow cover was inferred from near-surface ground temperature (GST) data, estimating between 130 and 275 days per year and 0.5 to 7.1 m snow thickness. Temperature and BTS data show that the lowest part of the talus slope and the rock glacier furrow are the coldest places in this cirque, coinciding with a more persistent and thickest snow cover. The highest temperatures coincide with less snow cover, fine-grained soils, and higher solar radiation. Snow cover has a primary role in controlling GST, as the delayed appearance in autumn or delayed disappearance in spring have a cooling effect, but no correlation with mean annual near-surface ground temperatures exists. Heavy rain-over-snow events have an important influence on the GST. In the talus slope, air circulation during the snow-covered period produces a cooling effect in the lower part, especially during the summer. Significant inter-annual GST differences were observed that exhibited BTS limitations. A slight positive temperature trend was detected but without statistically significance and less prominent than nearby reference official meteorological stations, so topoclimatic conditions reduced the more global positive temperature trend. Probable existence of permafrost in the rock glacier furrow and the lowest part of the talus slope is claimed; however, future work is necessary to confirm this aspect.

Long-term thermal effects of air convection embankments (ACEs) over 550-km-long permafrost zones along the Qinghai-Tibet railway were analyzed on the basis of 14-year records (2002-2016) of ground temperature. The results showed that, after embankment construction, permafrost tables beneath the ACEs moved upward quickly in the first 3years and then remained stable over the next 10years. The magnitude of this upward movement showed a positive correlation with embankment thickness. Shallow permafrost temperature beneath the ACEs decreased over a 5-year period after embankment construction in cold permafrost zones, but increased sharply concurrent with permafrost table upward movement in warm permafrost zones. Deep permafrost beneath all the ACEs showed a slow warming trend due to climate warming. Overall, the thermal effects of ACEs significantly uplifted underlying permafrost tables after embankment construction and then maintained them well in a warming climate. The different thermal effects of ACEs in cold and warm permafrost zones related to the working principle of the ACEs and natural ground thermal regime in the two zones. (c) 2018 American Society of Civil Engineers.