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The European Space Agency SnowSAR instrument is a side-looking, dual-polarised (VV/VH), X/Ku band synthetic aperture radar (SAR), operable from various sizes of aircraft. Between 2010 and 2013, the instrument was deployed at several sites in Northern Finland, Austrian Alps and northern Canada. The purpose of the airborne campaigns was to measure the backscattering properties of snow-covered terrain to support the development of snow water equivalent retrieval techniques using SAR. SnowSAR was deployed in Sodankylä, Northern Finland, for a single flight mission in March 2011 and 12 missions at two sites (tundra and boreal forest) in the winter of 2011–2012. Over the Austrian Alps, three flight missions were performed between November 2012 and February 2013 over three sites located in different elevation zones representing a montane valley, Alpine tundra and a glacier environment. In Canada, a total of two missions were flown in March and April 2013 over sites in the Trail Valley Creek watershed, Northwest Territories, representative of the tundra snow regime. This paper introduces the airborne SAR data and coincident in situ information on land cover, vegetation and snow properties. To facilitate easy access to the data record, the datasets described here are deposited in a permanent data repository (10.1594/PANGAEA.933255, Lemmetyinen et al., 2021). [ABSTRACT FROM AUTHOR]

The European Space Agency SnowSAR instrument is a side looking, dual polarized (VV/VH), X/Ku band synthetic aperture radar (SAR), operable from a small aircraft. Between 2010 and 2013, the instrument was deployed at several sites in Northern Finland, Austrian Alps, and northern Canada. The purpose of the airborne campaigns was to measure the backscattering properties of snow -covered terrain to support the development of snow water equivalent retrieval techniques using SAR. SnowSAR was deployed in Sodankylä, Northern Finland for a single flight mission in March 2011 and twelve missions at two sites (tundra and boreal forest) in the winter of 2011-2012. Over the Austrian Alps, three flight missions were performed between November 2012 and February 2013 over three sites located in different elevation zones, representing a montane valley, Alpine tundra, and a glacier environment. In Canada, a total of two missions were flown in March and April 2013, over sites in the Trail Valley Creek watershed, Northwest Territories, representative of the tundra snow regime. This paper introduces the airborne SAR data, as well as coincident in situ information on land cover, vegetation and snow properties. To facilitate easy access to the data record the datasets described here are deposited in a permanent data repository (https://doi.pangaea.de/ 10.1594/PANGAEA.933255; Lemmetyinen et al., 2021). A temporary link to access the data without login information is provided for reviewers of this manuscript: https://www.pangaea.de/tok/e8c562c3c8a15ac34daa83d00 c76fcb347330884. [ABSTRACT FROM AUTHOR]

The largest crystalline maß movement in the Alps, the Holocene Köfels rockslide (Tyrol, Austria), was re-investigated in order to study the influence of lithologies and geological structures on deep seated gravitational slope deformations. The slide debris detached from an east-facing slope and left a giant niche, where the geological and morphological conditions point to different types of failure mechanisms. According to the lithologies encountered in the scarp and accumulation area, the main source of the rapid Köfels rockslide is represented by a several hundred metres thick orthogneiß complex embedded in paragneißes of the Austroalpine Ötztal basement unit. Layering and foliation of both the orthogneißes and the surrounding paragneißes are orientated unfavourable to promote slope failures. Rather this slope collapse was clearly structurally predisposed by fault-related valley-deepening and the coalescence of different brittle fracture systems. The key-discontinuities that reduced here the rock maß strength and enabled the failure are two main fracture sets: in the orthogneißes, fracture set og#1 comprises the well-known 25-35° E-dipping sliding planes that daylight subparallel to the slope, set og#2 forms a cluster of 60-80° E- to NE-dipping fractures. In the paragneißes, the fractures measured show a similar but more scattering spatial distribution. Concerning the slope collapse, the newly compiled geological map indicates that the size of the southern scarp area, which is entirely made up by paragneiß series, obviously differs from the volume of according lithologies in the accumulation area. Based on these findings and the scarp morphology, considerable parts of the scarp niche, i.e. areas made up by incompetent paragneißes, were not involved in the rapid Köfels rockslide event but characterised by slowly creeping slope deformations. Furthermore the geological field surveys and remote sensing data, i.e. optical, laserscanner and InSAR images, show that the present-day head scarp is widely affected by post-failure slope deformations. As a major feature, en-echelon orientated steeply E-dipping fractures highly influence the rock maß anisotropy, reduce the strength of the orthogneißes and cause further slope instabilities. Also in the adjacent paragneißes, distinct double-crested ridges, several secondary scarps and extension zones are signs of ongoing rocksliding. As a whole, the Köfels site is an outstanding example of how deep-seated rock slope failures and their potential evolution are controlled by the lithological inventory and the structural setting. [ABSTRACT FROM AUTHOR]