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Advisor(s)
Abstract(s)
Relict and present-day periglacial features have
been reported in the literature for the upper reaches of the
High Atlas mountains, which is the highest range in North
Africa (Djebel Toubkal – 4167 m a.s.l.). A lobate feature in
the Irhzer Ikhibi south at 3800 m a.s.l. has been previously
interpreted as an active rock glacier, but no measurements of
ground or air temperatures are known to exist for the area. In
order to assess the possible presence of permafrost, we analyse data from June 2015 to June 2016 from two air temperature measurement sites at 2370 and 3210 m a.s.l. and from
four ground surface temperature (GST) sites at 3220, 3815,
3980 and 4160 m a.s.l. to characterize conditions along an altitudinal gradient along the Oued Ihghyghaye valley to the
summit of the Djebel Toubkal. GSTs were collected at 1 h
intervals, and the presence of snow cover at the monitoring
sites was validated using Landsat 8 and Sentinel-2 imagery.
Two field visits allowed for logger installation and collection and for assessing the geomorphological features in the
area. The results show that snow plays a major role on the
thermal regime of the shallow ground, inducing important
spatial variability. The lowest site at 3220 m had a thermal
regime characterized by frequent freeze–thaw cycles during
the cold season but with few days of snow. When snow settled, the ground surface remained isothermal at 0 ◦C , indicating the absence of permafrost. The highest sites at 3980
and 4160 m a.s.l. showed very frequent freeze–thaw cycles
and a small influence of the snow cover on GST, reflecting
the lack of snow accumulation due to the wind-exposed settings on a ridge and on the summit plateau. The site located
at 3815 m in the Irhzer Ikhibi south valley had a cold, stable thermal regime with GST varying from −4.5 to −6
◦C
from December to March, under a continuous snow cover.
The site’s location in a concave setting favours wind-driven
snow accumulation and lower incoming solar radiation due
to the shading effect of a ridge, inducing the conservation
of a thick snow pack. The stable and low GSTs are interpreted as a strong indicator of the probable presence of permafrost at this site, which is an interpretation supported by
the presence of lobate and arcuate features in the talus deposits. We present first results and further observations using
geophysics, and borehole measurements are foreseen. This is
the first time that probable permafrost has been reported from
temperature observations in the mountains of North Africa.
Description
Keywords
Permafrost North Africa
Pedagogical Context
Citation
Vieira, G., Mora, C., Faleh, A. (2017). New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco). Cryosphere, 11(4), 1691–1705. https://doi.org/10.5194/tc-11-1691-2017.
Publisher
Copernicus Publications