scholarly journals Understanding snow-transport processes shaping the mountain snow-cover

2010 ◽  
Vol 4 (4) ◽  
pp. 545-559 ◽  
Author(s):  
R. Mott ◽  
M. Schirmer ◽  
M. Bavay ◽  
T. Grünewald ◽  
M. Lehning
Keyword(s):  
Snow Cover ◽  
Laser Scanning ◽  
Transport Processes ◽  
Snow Surface ◽  
North West ◽  
Deposition Patterns ◽  
Regional Prediction ◽  
Prevailing Wind Direction ◽  
Snow Transport ◽  
Snow Deposition

Abstract. Mountain snow-cover is normally heterogeneously distributed due to wind and precipitation interacting with the snow cover on various scales. The aim of this study was to investigate snow deposition and wind-induced snow-transport processes on different scales and to analyze some major drift events caused by north-west storms during two consecutive accumulation periods. In particular, we distinguish between the individual processes that cause specific drifts using a physically based model approach. Very high resolution wind fields (5 m) were computed with the atmospheric model Advanced Regional Prediction System (ARPS) and used as input for a model of snow-surface processes (Alpine3D) to calculate saltation, suspension and preferential deposition of precipitation. Several flow features during north-west storms were identified with input from a high-density network of permanent and mobile weather stations and indirect estimations of wind directions from snow-surface structures, such as snow dunes and sastrugis. We also used Terrestrial and Airborne Laser Scanning measurements to investigate snow-deposition patterns and to validate the model. The model results suggest that the in-slope deposition patterns, particularly two huge cross-slope cornice-like drifts, developed only when the prevailing wind direction was northwesterly and were formed mainly due to snow redistribution processes (saltation-driven). In contrast, more homogeneous deposition patterns on a ridge scale were formed during the same periods mainly due to preferential deposition of precipitation. The numerical analysis showed that snow-transport processes were sensitive to the changing topography due to the smoothing effect of the snow cover.

scholarly journals Understanding snow-transport processes shaping the mountain snow-cover

2010 ◽  
Vol 4 (3) ◽  
pp. 865-900 ◽  
Author(s):  
R. Mott ◽  
M. Schirmer ◽  
M. Bavay ◽  
T. Grünewald ◽  
M. Lehning
Keyword(s):  
Snow Cover ◽  
Laser Scanning ◽  
Transport Processes ◽  
Snow Surface ◽  
North West ◽  
Deposition Patterns ◽  
Regional Prediction ◽  
Prevailing Wind Direction ◽  
Snow Transport ◽  
Snow Deposition

Abstract. Mountain snow-cover is normally heterogeneously distributed due to wind and precipitation interacting with the snow cover on various scales. The aim of this study was to investigate snow deposition and wind-induced snow transport processes on different scales and to analyze some major drift events caused by North-West storms during two consecutive accumulation periods. In particular, we distinguish between the individual processes that cause specific drifts using a physically based model approach. Very high resolution wind fields (5 m) were therefore computed with the atmospheric model Advanced Regional Prediction System (ARPS) and used as input for a model of snow surface processes (Alpine3D) to calculate saltation, suspension and preferential deposition of precipitation. Several flow features during North-West storms were identified with input from a high-density network of permanent and mobile weather stations and indirect estimations of wind directions from snow surface structures, such as snow dunes and sastrugis. We also used Terrestrial and Airborne Laser Scanning measurements to investigate snow deposition patterns and to validate the model. The model results suggest that the in-slope deposition patterns we found, particularly two huge cross-slope cornice-like drifts, developed only when the prevailing wind direction was northwesterly and were formed mainly due to snow redistribution processes (saltation-driven). In contrast, more homogeneous deposition patterns on a ridge scale were formed during the same periods mainly due to preferential deposition of precipitation. The numerical analysis showed that snow-transport processes were sensitive to the changing topography due to the smoothing effect of the snow cover.

Local simulations of snow redistribution by wind with an intermediate-complexity snow cover model driven by different wind downscaling methods

2021 ◽  
Author(s):  
Louis Quéno ◽  
Paul Morin ◽  
Rebecca Mott ◽  
Tobias Jonas
Keyword(s):  
Snow Cover ◽  
Transport Processes ◽  
Swiss Alps ◽  
Small Scale ◽  
Mountain Range ◽  
Model Framework ◽  
Intermediate Complexity ◽  
Operational Modelling ◽  
Snow Transport ◽  
Large Domains

<p>In mountainous terrain, wind-driven transport of deposited snow affects the overall distribution of snow, and can have a significant effect on snowmelt patterns even at coarser resolution.  In an operational modelling perspective, a compromise must be found to represent this complex small-scale process with enough accuracy while mitigating the computational costs of snow cover simulations over large domains. To achieve this compromise, we implemented the SNOWTRAN-3D snow transport module within the FSM intermediate complexity snow cover model. We included a new layering scheme and a historical variable of past snow wetting, but without resolving the snow microstructure. Simulations are run and evaluated over a small mountain range in the Swiss Alps at 25 to 100 m resolution. Being implemented in the model framework of the SLF operational snow hydrology service (OSHD), simulations further benefit from snow data assimilation techniques to provide improved estimates of solid precipitation fields. As complex wind patterns in mountains are the key processes driving snow transport, we tested statistical and dynamical methods to downscale 1 km resolution COSMO winds to better reflect topographically-induced flow patterns. These simulations are a first step working towards the integration of wind transport processes over large domains in an intermediate-complexity and -resolution operational modelling framework.</p>

scholarly journals Meteorological Modeling of Very High-Resolution Wind Fields and Snow Deposition for Mountains

2010 ◽  
Vol 11 (4) ◽  
pp. 934-949 ◽  
Author(s):  
Rebecca Mott ◽  
Michael Lehning
Keyword(s):  
High Resolution ◽  
Wind Field ◽  
Flow Fields ◽  
Swiss Alps ◽  
Mean Flow ◽  
Wind Fields ◽  
Advanced Regional Prediction System ◽  
Deposition Patterns ◽  
Regional Prediction ◽  
Snow Deposition

Abstract The inhomogeneous snow distribution found in alpine terrain is the result of wind and precipitation interacting with the snow surface. During major snowfall events, preferential deposition of snow and transport of previously deposited snow often takes place simultaneously. Both processes, however, are driven by the local wind field, which is influenced by the local topography. In this study, the meteorological model Advanced Regional Prediction System (ARPS) was used to compute mean flow fields of 50-m, 25-m-, 10-m-, and 5-m grid spacing to investigate snow deposition patterns resulting from two snowfall events on a mountain ridge in the Swiss Alps. Only the initial adaptation of the flow field to the topography is calculated with artificial boundary conditions. The flow fields then drive the snow deposition and transport module of Alpine3D, a model of mountain surface processes. The authors compare the simulations with partly new measurements of snow deposition on the Gaudergrat ridge. On the basis of these four grid resolutions, it was possible to investigate the effects of numerical resolution in the calculation of wind fields and in the calculation of the associated snow deposition. The most realistic wind field and deposition patterns were obtained with the highest resolution of 5 m. These high-resolution simulations confirm the earlier hypothesis that preferential deposition is active at the ridge scale and true redistribution—mainly via saltation—forms smaller-scale deposition patterns, such as dunes and cornices.

scholarly journals Specifics of boglands freezing in the north and northwest of the European part of Russia under climate change

2019 ◽  
Vol 59 (2) ◽  
pp. 233-244
Author(s):  
V. I. Batuev ◽  
I. L. Kalyuzhny
Keyword(s):  
Ambient Temperature ◽  
Snow Cover ◽  
Spatial And Temporal Variability ◽  
North West ◽  
The North ◽  
Climatic Period ◽  
European Part Of Russia ◽  
Freezing Depth ◽  
Main Factors ◽  
Cover Thickness

Long-term complex observations covering the period of 1949–2018 made possible to determine the average annual characteristics of the depth of freezing of wetlands in the North and Northwest of the European territory of Russia together with main factors of its formation, and spatial and temporal variability. The main factors that determine the depth of freezing of wetlands are ambient temperature, snow cover thickness, and a degree of watering of the micro landscape (water reserves of the micro landscape). At the initial stage of freezing, the major factor is the ambient temperature, when intensity of the freezing reaches 0.5–0.8 cm/day. As snow falls, the freezing rate becomes smaller, and when the snow cover thickness reaches 25–30 cm the depth amounts to 0.2–0.3 cm/day and smaller. It was found that the spatial variability of the freezing depth decreases from large values of the coefficient of variation (0.3–0.4) at the depth of 20–30 cm to less than 0.1 when the depth exceeds 60 cm. The largest values of the depth are recorded in the North of the Kola Peninsula, where sometimes they reach from 84 to 97 cm with the average values of 48–66. In large hummocky bogs, when the seasonal freezing comes down to 63–65 cm it links with the permafrost layer. On average, swamps of these bogs freeze down to a depth of 68 cm. The average climatic depth of freezing of oligotrophic bogs of the NorthWest is 21–24 cm; in some years, freezing of them reaches 32–40 cm. It has been shown that the relative warming of the climate resulted in decreasing in the depth of freezing of wetlands in the North and North-West of the European territory of Russia. Relative to the previous climatic period, the depth of frost penetration in the northern Ilasskoye bog decreased by 32%, and in north-western Lammin-Suo bog – by 31%.

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.

Offshore Wind Power Assessment on the East Coast of Saudi Arabia

2005 ◽  
Vol 29 (5) ◽  
pp. 409-419 ◽  
Author(s):  
Shafiqur Rehman
Keyword(s):  
Saudi Arabia ◽  
Wind Speed ◽  
Ghg Emissions ◽  
Resource Assessment ◽  
Offshore Wind ◽  
Energy Yield ◽  
North West ◽  
North East ◽  
Prevailing Wind Direction ◽  
Wind Resource

This paper, to the best of author's knowledge, presents the first wind resource assessment for offshore-wind energy off the mainland coasts of Saudi Arabia, despite the onshore wind resource being known. The study utilized wind speed data from, in effect, an offshore meteorological station to study the annual and seasonal variation of wind speed, wind speed frequency distribution, energy yield and consequent opportunity for reduction in green house gases (GHG) emissions. These results were compared with contemporaneous data from a mainland location ∼ 10 km inland at the same longitude Energy yields were calculated using HOMER and RetScreen models. The annual mean wind measured at Abu Ali Island, the offshore location, was 5.43 m/s. This is larger than the 4.9 m/s measured over the same period at Abu Kharuf, the nearby inland location. Larger wind speeds were found in winter months than in summer months at both locations. At Abu Ali Island, the power of the wind could be extracted for 75% of the time at hub-height of 60 meters using modern wind machines of cut-in-speed 4 m/s, in comparison with 60% of time at Abu Kharuf. The prevailing wind direction was found to be North (N), North West (NNW) and North East (NNE).

scholarly journals Observations of snowpack ripening in the Sierra Nevada, California, U.S.A.

1999 ◽  
Vol 45 (151) ◽  
pp. 409-416 ◽  
Author(s):  
Richard Kattelmann ◽  
Jeff Dozier
Keyword(s):  
Snow Cover ◽  
Latent Heat ◽  
Sierra Nevada ◽  
Ice Sheets ◽  
Snow Surface ◽  
Layer Development

AbstractThe transition from a dry, sub-freezing snow cover to isothermal snow freely conducting water was observed near timberline in the Sierra Nevada, California, U.S.A. Although there were few major stratigraphic boundaries in the snowpacks observed, minor textural discontinuities were sufficient to both route water laterally downslope and later create ice layers at these strata. During the first few days of snowmelt, downslope movement of water parallel to the strata allowed water to bypass lower layers of the snow cover on slopes and converge in microtopographic depressions on level terrain, creating isolated drains through the snowpack. In addition to these drains, flow fingers associated with holes in the ice sheets delivered water to the base of the snow several days prior to the thorough wetting of the snowpack. Formation of a series of ice lenses just below the snow surface every night released much more latent heat than did ice-layer development within the bulk of the snowpack or at its base.

scholarly journals Building a topological and geometrical model of poplar tree using portable on-ground scanning LIDAR

2008 ◽  
Vol 35 (10) ◽  
pp. 1080 ◽  
Author(s):  
Maurizio Teobaldelli ◽  
Alcoriza David Puig ◽  
Terenzio Zenone ◽  
Marco Matteucci ◽  
Günther Seufert ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Geometrical Model ◽  
Accurate Estimate ◽  
Horizontal Structure ◽  
Tree Structures ◽  
North West ◽  
Poplar Trees ◽  
Scanning Lidar ◽  
Architectural Characteristics ◽  
Poplar Tree

The objectives of this research were to investigate the suitability of advanced technologies like 3D-Laser scanning to acquire fair and sound information on structural and architectural characteristics of poplar stand, and to map topology of above-ground tree structures. The study area was an intensive poplar plantation located ~10 km north-west of the city of Pavia within the ‘Parco Regionale del Ticino’, Italy. A forest inventory of the poplar stand was conducted in 2005 and three 14-year-old poplar trees were selected and felled. The main architectural characteristics of poplar trees (destructive measurement) were compared with indirect measurement carried out using a portable on-ground scanning LIDAR IMAGER 5003 combined with the JRC-Reconstructor and AMAPmod softwares. The method permitted us to make an accurate estimate of the vertical and horizontal structure of the stand, to evaluate the stem and branches morphology of selected trees at different height in the canopy, and to create and validate multiscale representations of poplar tree architecture.

scholarly journals Snow Transport Over Mountain Crests

1980 ◽  
Vol 26 (94) ◽  
pp. 469-480 ◽  
Author(s):  
Paul M. B. Föhn
Keyword(s):  
Quantitative Relationship ◽  
Horizontal Wind ◽  
Snow Surface ◽  
Horizontal Wind Speed ◽  
Ridge Crest ◽  
Wind Speeds ◽  
Drift Flux ◽  
Strong Winds ◽  
Wind Profiles ◽  
Snow Transport

AbstractIn order to gain more insight into the mountain snow-transport mechanisms wind and drift flux measurements have been executed on a ridge crest (mainly during snow-storms). Horizontal wind-speed profiles, measured between 0.3 and 6 m above snow surface, show a hump-shaped course especially for strong winds. Theoretical approximations substantiate that the Bernoullian pressure decrease on the crest may be the main cause for this type of wind profile. Roughness parameters (Z0, u⋆) are determined with the aid of the wind profiles and compared with those reported in the literature. Corresponding drift density profiles coincide with steady-state drift theories as long as wind speeds are low (u1≤ 7-10 m s-1), at greater wind speeds snow plumes of 1 to 1.5 m thickness develop immediately above snow surface. Areal measurements on snow mass-balance differences between windward and lee slopes are used to approximate the total transport over the ridge crest and to derive a quantitative relationship between crest winds and drift-snow deposition on lee slopes.

Measurement of snow cover depth using 100 × 100 meters sampling plot and Structure from Motion method in Adventdalen, Svalbard

2016 ◽  
Vol 6 (2) ◽  
pp. 155-168
Author(s):  
Radim Stuchlík ◽  
Jan Russnák ◽  
Tomáš Plojhar ◽  
Zdeněk Stachoň
Keyword(s):  
Spatial Distribution ◽  
Snow Cover ◽  
Structure From Motion ◽  
Snow Depth ◽  
Surface Model ◽  
Snow Surface ◽  
Reference Volume ◽  
Snow Cover Depth ◽  
Sampling Plot ◽  
Motion Method

We tried to verify the concept of Structure from Motion method for measuring the volume of snow cover in a grid of 100×100 m located in Adventdalen, Central Svalbard. As referencing method we utilized 121 depth measurements in one hectare area. Using avalanche probe a snow depth was measured in mentioned 121 nodes of the grid. We detected maximum snow depth of 2.05 m but snowless parts as well. From gathered depths’ data we geostatistically (ordinary kriging) interpolated snow surface model which we used to determine reference volume of snow at research plot (5 569 m3). As a result, we were able to calculate important metrics and analyze topography and spatial distribution of snow cover at the plot. For taking photos for Structure from Motion method, bare pole in hands with a camera mounted was used. We constructed orthomosaic of research plot.

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