The Distribution, Thermal Characteristics and Dynamics of Permafrost in Tröllaskagi, Northern Iceland, as Inferred from the Distribution of Rock Glaciers and Ice‐Cored Moraines

Abstract

Knowledge of the characteristics and spatial distribution of permafrost in Iceland is important to understanding slope stability, climate change impacts and palaeo‐glaciology. The permafrost distribution there, however, is poorly constrained. The presence of rock glaciers and stable ice‐cored moraines in mountain settings relates to permafrost, making such landforms indicators of present or past permafrost. This study combines recently published aerial photographs (2002–07), radar interferometry based on Advanced Land Observing Satellite phased array type L‐band synthetic aperture radar (ALOS PALSAR) data (2007), land surface temperatures estimated from moderate‐resolution imaging spectroradiometer satellite data (MODIS; 2003–10) and field mapping to re‐examine the permafrost distribution, thermal characteristics and dynamics on the Tröllaskagi peninsula. An inventory of 265 landforms, mostly active or inactive (intact), categorised them by genesis and activity, the latter independently investigated by PALSAR interferometry. Intact landforms are mainly glacigenic, occurring as moraine‐derived rock glaciers or ice‐cored moraines. Their dominant orientation is between north and northeast, suggesting that topography and exposure influence their present‐day formation. Permafrost landforms exist at all elevations on the Tröllaskagi peninsula, with intact landforms at high elevations and relict landforms reaching down to sea level. Rock glaciers at sea level may imply early deglaciation of northern Iceland. Copyright © 2013 John Wiley & Sons, Ltd.

The origin of glacial alpine landscape in Tröllaskagi Peninsula (North Iceland)

“…This permafrost model shows the extensive and almost continuous presence of permafrost in the Trolläskagi Peninsula, with a limit at around 800-900 m. Lilleøren et al (2013) confirm the existence of permafrost currently above 800 m a.s.l. at certain inland locations in Tröllaskagi.…”

“…Ages of the erratic and fossil rock glacier boulders are indicated, according to Palacios et al (2015Palacios et al ( , 2016. Lilleøren et al (2013) identified 265 landforms related to the presence of permafrost in Tröllaskagi, of which 178 are rock glaciers and 87 debris-covered glaciers. The Nautárdalur is the only rock glacier which has been monitored in Tröllaskagi (Martin and Whalley, 1987;Martin et al, 1991;Whalley and Martin, 1994;Hamilton and Whalley, 1995).…”

“…Kellerer-Pirklbauer et al (2007) also studied the rock glacier dynamics in Fremri-Grjótárdalur and confirmed a velocity range from 0.06 m yr -1 to 0.74 m yr -1 . Lilleøren et al (2013) monitored the dynamics of various debris-covered and rock glaciers in the south of Hóladalur using techniques based on satellite radar interferometry (ALOS polarimetric PALSAR images between 16 August and 1 October 2007) and calculated velocities between 0.2-0.5 m yr -1 , with maximum velocities exceeding 3 m yr -1 . Tanarro et al (2015Tanarro et al ( , 2016 produce the comparison and visual recognition of the superficial landforms of the Fremri-Grjótárdalur rock glaciers and the Hóladalsjökull debris-covered glacier using georeferencing, contrasting a 1946 aerial photograph, a 2000 orthophoto and the 2013 image from Google Earth (Fig.…”

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

“…These so-called push moraines are very common at the cold glacier margins in permafrost environments (Etzelmüller and Hagen, 2005;Matthews et al, 2014;Dusik et al, 2015). As it currently occurs in the study sites (Figures 6B, 7), differential flow and ablation induce the progressive disconnection between rock glaciers and the upslope glacier zones in negative mass balance periods (Ackert, 1998;Ribolini et al, 2010;Lilleøren et al, 2013). The internal structure to the North of Tsarmine illustrates this situation: a lens of sedimentary ice (distal zone of Tsa-4; Figure 5) may have been recently integrated into the distal former frozen sediments (Tsa-3).…”

Decadal evolution of a very small heavily debris-covered glacier in an Alpine permafrost environment

“…Ablation rate is then significantly reduced in these environments when the thickness of the debris cover is close to that of the permafrost active layer (i.e. seasonally thawing layer; Lilleøren and others, 2013). At the glacier margins, the deposition of the large amount of debris may induce the build-up of moraine dams (Benn and others, 2003;Iturrizaga, 2013).…”