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The surface energy balance is a key factor influencing the ground thermal regime. With ongoing climate change, it is crucial to understand the interactions of the individual heat fluxes at the surface and within the subsurface layers, as well as their relative impacts on the permafrost thermal regime. A unique set of high-altitude meteorological measurements was analysed to determine the energy balance at three mountain permafrost sites in the Swiss Alps (Murtèl–Corvatsch, Schilthorn and Stockhorn), where data have been collected since the late 1990s in the framework of the Swiss Permafrost Monitoring Network (PERMOS). All stations are equipped with sensors for four-component radiation, air temperature, humidity, and wind speed and direction, as well as ground temperatures and snow height. The three sites differ considerably in their surface and ground material composition, as well as their ground ice contents. The energy fluxes were calculated based on two decades of field measurements. While the determination of the radiation budget and the ground heat flux is comparatively straightforward (by the four-component radiation sensor and thermistor measurements within the boreholes), larger uncertainties exist for the determination of turbulent sensible and latent heat fluxes. Our results show that mean air temperature at Murtèl–Corvatsch (1997–2018, 2600 m a.s.l.) is -1.66 ∘ C and has increased by about 0.8 ∘ C during the measurement period. At the Schilthorn site (1999–2018, 2900 m a.s.l.) a mean air temperature of -2.60 ∘ C with a mean increase of 1.0 ∘ C was measured. The Stockhorn site (2003–2018, 3400 m a.s.l.) recorded lower air temperatures with a mean of -6.18 ∘ C and an increase of 0.5 ∘ C. Measured net radiation, as the most important energy input at the surface, shows substantial differences with mean values of 30.59 W m -2 for Murtèl–Corvatsch, 32.40 W m -2 for Schilthorn and 6.91 W m -2 for Stockhorn. The calculated turbulent fluxes show values of around 7 to 13 W m -2 using the Bowen ratio method and 3 to 15 W m -2 using the bulk method at all sites. Large differences are observed regarding the energy used for the melting of the snow cover: at Schilthorn a value of 8.46 W m -2 , at Murtèl–Corvatsch 4.17 W m -2 and at Stockhorn 2.26 W m -2 are calculated, reflecting the differences in snow height at the three sites. In general, we found considerable differences in the energy fluxes at the different sites. These differences help to explain and interpret the causes of a warming atmosphere. We recognise a strong relation between the net radiation and the ground heat flux. Our results further demonstrate the importance of long-term monitoring to better understand the impacts of changes in the surface energy balance components on the permafrost thermal regime. The dataset presented can be used to improve permafrost modelling studies aiming at, for example, advancing knowledge about permafrost thaw processes. The data presented and described here are available for download at the following site: 10.13093/permos-meteo-2021-01. [ABSTRACT FROM AUTHOR]

We present an experimental study of natural hyperconcentrated flows of fine sediment from Draix-Bleone observatory. Suspensions of volumic concentration ranging from 29 to 44% were tested in a rheometer and exhibit a Herschel–Bulkley behaviour. Suspensions of volumic concentration ranging from 0 to 31% were tested in flume experiments with varying slope and discharge. Velocity profile measurements indicate a transition from turbulent Newtonian flows to laminar non-Newtonian flows as the concentration increases. Rheological data and flume velocity profiles consistently suggest that a yield stress appears for volumic concentrations higher than 26–29%. Finally, the relation between the Reynolds number and the friction coefficient computed for all flume experiments is found to follow a unique trend, independently of the concentration. This allows the laminar, transitional and turbulent regimes to be identified, and suggests that transitional to laminar conditions can be observed in the field during hyperconcentrated events. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale information on habitat suitability is indispensable for planning management actions to further endangered species with large-spatial requirements. So far, remote sensing based habitat variables mostly included environmental and land cover data derived from passive sensors, but lacked information on vegetation structure. This is a serious constraint for the management of endangered species with specific structural requirements. Light detection and ranging (LiDAR), in contrast to passive remote sensing techniques, may bridge this gap in structural information at the landscape scale. We investigated the potential of LiDAR data to quantify habitat suitability for capercaillie (Tetrao urogallus), an endangered forest grouse in Central Europe, in a forest reserve of 17.7km2. We used continuous variables of horizontal and vertical stand structure from first and last pulse LiDAR data and presence–absence information from field work to model habitat suitability with generalized linear models (GLM). The two final habitat suitability models explained the observed presence–absence pattern moderately well (AUC of 0.71 and 0.77) with horizontal structure explaining better than vertical structure. Relative tree canopy cover was the most important variable with intermediate values indicating highest habitat suitability. As such, LiDAR allowed us to translate the results from habitat modeling at the landscape scale to effective management recommendations at the local scale at a level of detail that hitherto was unavailable for large areas. LiDAR thus enabled us to integrate individual habitat preferences at the scale of entire populations and thus offers great potential for effective habitat monitoring and management of endangered species. [Copyright &y& Elsevier]