scholarly journals Modeling spatially distributed snow instability at a regional scale using Alpine3D

2021 ◽  
pp. 1-16
Author(s):  
Bettina Richter ◽  
Jürg Schweizer ◽  
Mathias W. Rotach ◽  
Alec van Herwijnen
Keyword(s):  
Laser Scanning ◽  
Meteorological Data ◽  
Regional Scale ◽  
Winter Season ◽  
Horizontal Resolution ◽  
Distributed Modeling ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Snow Stratigraphy ◽  
Spatially Distributed

Abstract Assessing the avalanche danger level requires snow stratigraphy and instability data. As such data are usually sparse, we investigated whether distributed snow cover modeling can be used to provide information on spatial instability patterns relevant for regional avalanche forecasting. Using Alpine3D, we performed spatially distributed simulations to evaluate snow instability for the winter season 2016–17 in the region of Davos, Switzerland. Meteorological data from automatic weather stations were interpolated to 100 m horizontal resolution and precipitation was scaled with snow depth measurements from airborne laser scanning. Modeled snow instability metrics assessed for two different weak layers suggested that the weak layer closer to the snow surface was more variable. Initially, it was less stable than the weak layer closer to the ground, yet it stabilized faster as the winter progressed. In spring, the simulated snowpack on south-facing slopes stabilized faster than on north-facing slopes, in line with the regional avalanche forecast. In the winter months January to March 2017, simulated instability metrics did not suggest that the snowpack on south-facing slopes was more stable, as reported in the regional avalanche forecast. Although a validation with field data is lacking, these model results still show the potential and challenges of distributed modeling for supporting operational avalanche forecasting.

A tracking algorithm to identify slab and weak layer combinations for assessing snow instability and avalanche problem type

2021 ◽  
Author(s):  
Benjamin Reuter ◽  
Léo Viallon-Galinier ◽  
Stephanie Mayer ◽  
Pascal Hagenmuller ◽  
Samuel Morin
Keyword(s):  
Snow Cover ◽  
Winter Season ◽  
Essential Element ◽  
Problem Type ◽  
Model Output ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Problem Types ◽  
Snow Stratigraphy ◽  
Wet Snow

<p>Snow cover models have mostly been developed to support avalanche forecasting. Recently developed snow instability metrics can help interpreting modeled snow cover data. However, presently snow cover models cannot forecast the relevant avalanche problem types – an essential element to describe avalanche danger. We present an approach to detect, track and assess weak layers in snow cover model output data to eventually assess the related avalanche problem type. We demonstrate the applicability of this approach with both, SNOWPACK and CROCUS snow cover model output for one winter season at Weissfluhjoch. We introduced a classification scheme for four commonly used avalanche problem types including new snow, wind slabs, persistent weak layers and wet snow, so different avalanche situations during a winter season can be classified based on weak layer type and meteorological conditions. According to the modeled avalanche problem types and snow instability metrics both models produced weaknesses in the modeled stratigraphy during similar periods. For instance, in late December 2014 the models picked up a non-persistent as well as a persistent weak layer that were both observed in the field and caused widespread instability in the area. Times when avalanches released naturally were recorded with two seismic avalanche detection systems, and coincided reasonably well with periods of low modeled stability. Moreover, the presented approach provides the avalanche problem types that relate to the observed natural instability which makes the interpretation of modeled snow instability metrics easier. As the presented approach is process-based, it is applicable to any model in any snow avalanche climate. It could be used to anticipate changes in avalanche problem type due to changing climate. Moreover, the presented approach is suited to support the interpretation of snow stratigraphy data for operational forecasting.</p>

Simulating snow instability in complex terrain

2020 ◽  
Author(s):  
Bettina Richter ◽  
Alec van Herwijnen ◽  
Mathias W. Rotach ◽  
Jürg Schweizer
Keyword(s):  
Spatial Variability ◽  
Snow Cover ◽  
Complex Terrain ◽  
Laser Scanning ◽  
Winter Season ◽  
Temporal Variations ◽  
Full Potential ◽  
Avalanche Forecasting ◽  
Snow Stratigraphy ◽  
Operational Forecasting

<p><span>Numerical snow cover models are increasingly used in operational avalanche forecasting. While these models can provide snow stratigraphy and some snow instability information, their full potential is not yet exploited in forecasting. We investigated, how well the snow cover model Alpine3D simulated spatial and temporal variations in snow instability. Therefore, simulations were performed in highly varying complex terrain for the winter season 2016-2017 in the region of Davos, Switzerland for an area of about 21 km x 21 km. Alpine3D was forced with data from several automatic weather stations within the region, which were interpolated to a resolution of 100 m. To reproduce observed spatial variability, we scaled precipitation input with snow height measurements derived with airborne laser scanning. For comparison, we also simulated the snowpack without scaling. The simulation with scaling precipitation showed significantly higher spatial variability in modeled snow instability than the simulation without scaling. However, when information was aggregated to aspect and elevation dependent information for the whole region, as it is done for operational forecasting, this variability vanished and scaling precipitation seems unnecessary. At the beginning of the season and towards the end, snow instability depended on aspect, while in the winter months December to March, differences between different aspects were small. The simulations with scaling precipitation revealed a strong influence of snow depth on snow instability, although the various snow instability criteria provided inconsistent results. Simulated profiles, which were classified as rather favourable were rated as rather unstable and vice versa. A comparison to traditional snow profiles shows that snow stratigraphy was reproduced well, but assessing snow instability from stratigraphy alone is not feasible.</span></p>

scholarly journals Simulation of wind-induced snow transport in alpine terrain using a fully coupled snowpack/atmosphere model

2013 ◽  
Vol 7 (3) ◽  
pp. 2191-2245 ◽  
Author(s):  
V. Vionnet ◽  
E. Martin ◽  
V. Masson ◽  
G. Guyomarc'h ◽  
F. Naaim-Bouvet ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Winter Season ◽  
Coupled Model ◽  
Deposition Process ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Blowing Snow ◽  
Erosion And Deposition ◽  
Atmospheric Flow ◽  
Snow Transport

Abstract. In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It couples directly the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. A detailed representation of the first meters of the atmosphere allows a fine reproduction of the erosion and deposition process. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). For this purpose, a blowing snow event without concurrent snowfall has been selected and simulated. Results show that the model captures the main structures of atmospheric flow in alpine terrain, the vertical profile of wind speed and the snow particles fluxes near the surface. However, the horizontal resolution of 50 m is found to be insufficient to simulate the location of areas of snow erosion and deposition observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction in deposition of 5.3%. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

scholarly journals Validating modeled critical crack length for crack propagation in the snow cover model SNOWPACK

2019 ◽  
Vol 13 (12) ◽  
pp. 3353-3366 ◽  
Author(s):  
Bettina Richter ◽  
Jürg Schweizer ◽  
Mathias W. Rotach ◽  
Alec van Herwijnen
Keyword(s):  
Grain Size ◽  
Crack Propagation ◽  
Crack Length ◽  
Snow Cover ◽  
Field Experiments ◽  
Critical Crack ◽  
Critical Crack Length ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Snow Stratigraphy

Abstract. Observed snow stratigraphy and snow stability are of key importance for avalanche forecasting. Such observations are rare and snow cover models can improve the spatial and temporal resolution. To evaluate snow stability, failure initiation and crack propagation have to be considered. Recently, a new stability criterion relating to crack propagation, namely the critical crack length, was implemented into the snow cover model SNOWPACK. The critical crack length can also be measured in the field with a propagation saw test, which allows for an unambiguous comparison. To validate and improve the parameterization for the critical crack length, we used data from 3 years of field experiments performed close to two automatic weather stations above Davos, Switzerland. We monitored seven distinct weak layers and performed in total 157 propagation saw tests on a weekly basis. Comparing modeled to measured critical crack length showed some discrepancies stemming from model assumption. Hence, we replaced two variables of the original parameterization, namely the weak layer shear modulus and thickness, with a fit factor depending on weak layer density and grain size. With these adjustments, the normalized root-mean-square error between modeled and observed critical crack lengths decreased from 1.80 to 0.28. As the improved parameterization accounts for grain size, values of critical crack lengths for snow layers consisting of small grains, which in general are not weak layers, become larger. In turn, critical weak layers appear more prominently in the vertical profile of critical crack length simulated with SNOWPACK. Hence, minimal values in modeled critical crack length better match observed weak layers. The improved parameterization of critical crack length may be useful for both weak layer detection in simulated snow stratigraphy and also providing more realistic snow stability information – and hence may improve avalanche forecasting.

scholarly journals Integrated Methodologies for the 3D Survey and the Structural Monitoring of Industrial Archaeology: The Case of the Casalecchio di Reno Sluice, Italy

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Gabriele Bitelli ◽  
Giorgia Gatta ◽  
Valentina Alena Girelli ◽  
Luca Vittuari ◽  
Antonio Zanutta
Keyword(s):  
Laser Scanning ◽  
3D Model ◽  
Regional Scale ◽  
Winter Season ◽  
Structural Monitoring ◽  
Industrial Archaeology ◽  
Aerial Photogrammetry ◽  
Before And After ◽  
Close Range ◽  
The Stability

The paper presents an example of integrated surveying and monitoring activities for the control of an ancient structure, the Casalecchio di Reno sluice, located near Bologna, Italy. Several geomatic techniques were applied (classical topography, high-precision spirit levelling, terrestrial laser scanning, digital close-range photogrammetry, and thermal imagery). All these measurements were put together in a unique reference system and used in order to study the stability and the movements of the structure over the period of time observed. Moreover, the metrical investigations allowed the creation of a 3D model of the structure, and the comparison between two situations, before and after the serious damages suffered by the sluice during the winter season 2008-2009. Along with the detailed investigations performed on individual portions of the structure, an analysis of the whole sluice, carried out at a regional scale, was done via the use of aerial photogrammetry, using both recently acquired images and historical photogrammetric coverage. The measurements were carried out as part of a major consolidation and restoration activity, carried out by the “Consorzio della Chiusa di Casalecchio e del Canale di Reno”.

scholarly journals Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation

2017 ◽  
Vol 11 (1) ◽  
pp. 217-228 ◽  
Author(s):  
Johan Gaume ◽  
Alec van Herwijnen ◽  
Guillaume Chambon ◽  
Nander Wever ◽  
Jürg Schweizer
Keyword(s):  
Crack Propagation ◽  
Slope Angle ◽  
Critical Length ◽  
Snow Layer ◽  
Critical Crack ◽  
Critical Crack Length ◽  
New Model ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Recent Developments

Abstract. The failure of a weak snow layer buried below cohesive slab layers is a necessary, but insufficient, condition for the release of a dry-snow slab avalanche. The size of the crack in the weak layer must also exceed a critical length to propagate across a slope. In contrast to pioneering shear-based approaches, recent developments account for weak layer collapse and allow for better explaining typical observations of remote triggering from low-angle terrain. However, these new models predict a critical length for crack propagation that is almost independent of slope angle, a rather surprising and counterintuitive result. Based on discrete element simulations we propose a new analytical expression for the critical crack length. This new model reconciles past approaches by considering for the first time the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The crack begins to propagate when the stress induced by slab loading and deformation at the crack tip exceeds the limit given by the failure envelope of the weak layer. The model can reproduce crack propagation on low-angle terrain and the decrease in critical length with increasing slope angle as modeled in numerical experiments. The good agreement of our new model with extensive field data and the ease of implementation in the snow cover model SNOWPACK opens a promising prospect for improving avalanche forecasting.

A framework for automated and spatially-distributed modeling with the Agricultural Policy Environmental eXtender (APEX) model

2021 ◽  
pp. 105147
Author(s):  
Feng Pan ◽  
Qingyu Feng ◽  
Ryan McGehee ◽  
Bernard A. Engel ◽  
Dennis C. Flanagan ◽  
...  
Keyword(s):  
Agricultural Policy ◽  
Distributed Modeling ◽  
Spatially Distributed ◽  
Apex Model

scholarly journals Little Ice Age (Neoglacial) Paleoenvironmental Conditions At Siple Station, Antarctica

1990 ◽  
Vol 14 ◽  
pp. 199-204 ◽  
Author(s):  
Ellen Mosley-Thompson ◽  
Lonnie G. Thompson ◽  
Pieter M. Grootes ◽  
N. Gundestrup
Keyword(s):  
Little Ice Age ◽  
Regional Differences ◽  
Meteorological Data ◽  
Ice Core ◽  
Observational Evidence ◽  
Ice Age ◽  
Temperature Pattern ◽  
South Pole ◽  
Atmospheric Conditions ◽  
Spatially Distributed

The 550-year records of δ18O and dust concentrations from Siple Station, Antarctica suggest warmer and less dusty atmospheric conditions from 1600 to 1830 A.D. which encompasses much of the northern hemisphere Little Ice Age (LIA). Dust and δ18O data from South Pole Station indicate that the opposite conditions (e.g. cooler and more dusty) were prevalent there during the LIA. Meteorological data from 1945–85 show that the LIA temperature opposition between Amundsen-Scott and Siple, inferred from δ18O, is consistent with the present spatial distribution of surface temperature. There is some observational evidence suggesting that under present conditions stronger zonal westerlies produce a temperature pattern similar to that of the LIA. These regional differences demonstrate that a suite of spatially distributed, high resolution ice-core records will be necessary to characterize the LIA in Antarctica

Impacts of road access on lake trout (Salvelinus namaycush) populations: regional scale effects of overexploitation and the introduction of smallmouth bass (Micropterus dolomieu)

2009 ◽  
Vol 66 (2) ◽  
pp. 212-223 ◽  
Author(s):  
Scott D. Kaufman ◽  
Ed Snucins ◽  
John M. Gunn ◽  
Wayne Selinger
Keyword(s):  
Lake Trout ◽  
Scale Effects ◽  
Regional Scale ◽  
Winter Season ◽  
Salvelinus Namaycush ◽  
Smallmouth Bass ◽  
Micropterus Dolomieu ◽  
Excessive Pressure ◽  
Fishing Activity ◽  
Remote Lakes

In lake trout ( Salvelinus namaycush ) lakes of northeastern Ontario, Canada, aerial surveys of fishing activity on individual lakes (N = 589) and quantitative gillnet surveys (N = 65) were used to assess the effects of road access on angling effort and the presence of introduced smallmouth bass ( Micropterus dolomieu ). Angling effort, particularly during the open-water season, was highest and often exceeded estimated sustainable levels on lakes with good road access. Approximately 25% of the remote lakes also received excessive pressure during the winter season. Angler numerical responses to lake trout abundance were detected in remote lakes, but not in road-accessible lakes. Smallmouth bass were more prevalent in lakes with road access and human settlement (either cottages or lodges), supporting the theory that they were introduced into these lakes. Lake trout populations were depleted throughout much of the study range. Even without road access or smallmouth bass, lake trout abundance was still 47% lower than in unexploited reference lakes. When bass and (or) road access were present, lake trout abundance decreased by 77%. Remote lake trout populations in this area are clearly vulnerable to the negative impacts of improved access, a vector for both overexploitation and species introductions.

scholarly journals Recording microscale variations in snowpack layering using near-infrared photography

2010 ◽  
Vol 56 (195) ◽  
pp. 75-80 ◽  
Author(s):  
Ken D. Tape ◽  
Nick Rutter ◽  
Hans-Peter Marshall ◽  
Richard Essery ◽  
Matthew Sturm
Keyword(s):  
Near Infrared ◽  
Digital Camera ◽  
Post Processing ◽  
Snow Layer ◽  
Avalanche Forecasting ◽  
The North ◽  
Nir Imaging ◽  
Snow Stratigraphy ◽  
Wind Events ◽  
Lateral Variations

AbstractDeposition of snow from precipitation and wind events creates layering within seasonal snowpacks. The thickness and horizontal continuity of layers within seasonal snowpacks can be highly variable, due to snow blowing around topography and vegetation, and this has important implications for hydrology, remote sensing and avalanche forecasting. In this paper, we present practical field and post-processing protocols for recording lateral variations in snow stratigraphy using near-infrared (NIR) photography. A Fuji S9100 digital camera, modified to be sensitive to NIR wavelengths, was mounted on a rail system that allowed for rapid imaging of a 10 m long snow trench excavated on the north side of Toolik Lake, Alaska (68°38′ N, 149°36′ W). Post-processing of the images included removal of lens distortion and vignetting. A tape measure running along the base of the trench provided known locations (control points) that permitted scaling and georeferencing. Snow layer heights estimated from the NIR images compared well with manual stratigraphic measurements made at 0.2 m intervals along the trench (n = 357, R2 = 0.97). Considerably greater stratigraphic detail was captured by the NIR images than in the manually recorded profiles. NIR imaging of snow trenches using the described protocols is an efficient tool for quantifying continuous microscale variations in snow layers and associated properties.

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