scholarly journals GEOtop 2.0: simulating the combined energy and water balance at and below the land surface accounting for soil freezing, snow cover and terrain effects

2013 ◽  
Vol 6 (4) ◽  
pp. 6279-6341 ◽  
Author(s):  
S. Endrizzi ◽  
S. Gruber ◽  
M. Dall'Amico ◽  
R. Rigon
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Three Dimensional ◽  
Soil Surface ◽  
Soil Freezing ◽  
Subsurface Water ◽  
Energy Budgets ◽  
Small Scale ◽  
Freezing And Thawing ◽  
Linear Interaction

Abstract. GEOtop is a small-scale grid-based simulator that represents the heat and water budgets at and below the soil surface. It represents the energy exchange with the atmosphere, considering the radiative and turbulent fluxes, and describes the three-dimensional subsurface water flow. Furthermore, it reproduces the highly non-linear interaction of the water and energy balance during soil freezing and thawing, and describes the temporal evolution of water and energy budgets in the snow cover and their effect on soil temperature. Here, we describe the core components of GEOtop 2.0 and demonstrate its functioning. Based on a synthetic simulation, we show that the interaction of processes represented in GEOtop 2.0 can result in phenomena that are significant and relevant for applications involving permafrost and seasonally-frozen soils, both in high altitude and latitude regions.

scholarly journals GEOtop 2.0: simulating the combined energy and water balance at and below the land surface accounting for soil freezing, snow cover and terrain effects

2014 ◽  
Vol 7 (6) ◽  
pp. 2831-2857 ◽  
Author(s):  
S. Endrizzi ◽  
S. Gruber ◽  
M. Dall'Amico ◽  
R. Rigon
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Three Dimensional ◽  
Soil Surface ◽  
Soil Freezing ◽  
Energy Budgets ◽  
Freezing And Thawing ◽  
Terrain Effects ◽  
Synthetic Simulation ◽  
Soil Freezing And Thawing

Abstract. GEOtop is a fine-scale grid-based simulator that represents the heat and water budgets at and below the soil surface. It describes the three-dimensional water flow in the soil and the energy exchange with the atmosphere, considering the radiative and turbulent fluxes. Furthermore, it reproduces the highly non-linear interactions between the water and energy balance during soil freezing and thawing, and simulates the temporal evolution of the water and energy budgets in the snow cover and their effect on soil temperature. Here, we present the core components of GEOtop 2.0 and demonstrate its functioning. Based on a synthetic simulation, we show that the interaction of processes represented in GEOtop 2.0 can result in phenomena that are significant and relevant for applications involving permafrost and seasonally frozen soils, both in high altitude and latitude regions.

scholarly journals Autumn, Winter and Spring Soil Temperatures in Okstindan, Norway

1974 ◽  
Vol 13 (69) ◽  
pp. 521-533
Author(s):  
Charles Harris
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Soil Surface ◽  
Soil Freezing ◽  
Dominant Factor ◽  
Freezing And Thawing ◽  
Short Term ◽  
Air Temperatures ◽  
Soil Temperatures ◽  
Freezing And Thawing Cycles

Soil temperatures were recorded over periods of several weeks in the years 1909 and 1970 in two sites to a depth of 100 cm. It was found that snow depth was of major importance in the rate of freezing of the soil in winter; where snow cover was less than 5 cm in depth freezing rates were almost double those where snow depth was over 1 m. Snow cover also insulated the soil surface from above-zero air temperatures during spring, and soil thawing commenced from the surface only following the clearance of snow. Similarly, insulation of the soil surface by snow prevented short-term freezing and thawing cycles penetrating the soil, although even where snow cover was absent such short-term cycles were not observed to penetrate the soil to depths in excess of 5 cm. This surficial freezing and thawing of the soil took place more readily in spring than in the autumn. It was concluded that the annual cycle of soil freezing and thawing was the dominant factor in the thermal regime of these soils, short-term freezing cycles affecting only the immediate surface soil layers.

scholarly journals Autumn, Winter and Spring Soil Temperatures in Okstindan, Norway

1974 ◽  
Vol 13 (69) ◽  
pp. 521-533 ◽  
Author(s):  
Charles Harris
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Soil Surface ◽  
Soil Freezing ◽  
Dominant Factor ◽  
Freezing And Thawing ◽  
Short Term ◽  
Air Temperatures ◽  
Soil Temperatures ◽  
Freezing And Thawing Cycles

Soil temperatures were recorded over periods of several weeks in the years 1909 and 1970 in two sites to a depth of 100 cm. It was found that snow depth was of major importance in the rate of freezing of the soil in winter; where snow cover was less than 5 cm in depth freezing rates were almost double those where snow depth was over 1 m. Snow cover also insulated the soil surface from above-zero air temperatures during spring, and soil thawing commenced from the surface only following the clearance of snow. Similarly, insulation of the soil surface by snow prevented short-term freezing and thawing cycles penetrating the soil, although even where snow cover was absent such short-term cycles were not observed to penetrate the soil to depths in excess of 5 cm. This surficial freezing and thawing of the soil took place more readily in spring than in the autumn. It was concluded that the annual cycle of soil freezing and thawing was the dominant factor in the thermal regime of these soils, short-term freezing cycles affecting only the immediate surface soil layers.

scholarly journals Influence of snow cover on soil freezing and thawing in the West Spitsbergen

2015 ◽  
Vol 124 (4) ◽  
pp. 52 ◽  
Author(s):  
A. B. Shmakin ◽  
N. I. Osokin ◽  
A. V. Sosnovsky ◽  
E. P. Zazovskaya ◽  
A. V. Borzenkova
Keyword(s):  
Snow Cover ◽  
Soil Freezing ◽  
Freezing And Thawing ◽  
The West ◽  
West Spitsbergen ◽  
Soil Freezing And Thawing

Capturing watershed water balance with a physically-based two-hydrological-variable model: Application to the Little Washita basin

2021 ◽  
Author(s):  
Fanny Picourlat ◽  
Emmanuel Mouche ◽  
Claude Mugler
Keyword(s):  
Water Balance ◽  
Water Table ◽  
Land Surface ◽  
Large Scale ◽  
Three Dimensional ◽  
Hydrological Processes ◽  
Small Scale ◽  
Variable Model ◽  
Continental Hydrology ◽  
Hydrological Variable

<p>Hydrological processes import across scales is known to constitute a key challenge to improve their representation in large-scale land surface models. Since these models describe continental hydrology with vertical one dimensional infiltration and evapotranspiration, the challenge mainly resides in the dimensionality reduction of the processes. Departing from the catchment three-dimensional scale, previous work has shown that an equivalent two-dimensional hillslope model is able to simulate long term watershed water balance with good accuracy. This work has been done on the Little Washita basin (Ok, USA) using the integrated code HydroGeoSphere. Following this framework, we show that hillslope hydrology can be described by using realistic simplifying assumptions, such as linear water table profile. These assumptions allow the writing of an analytical model relying on two hydrological variables: the seepage face extension, which describe the intersection length between the water table and the land surface, and the water table slope. The last step of the work will be to use these key variables and this simplified description of the driving processes for importing small-scale hydrological processes into large-scale models.</p>

Effects of Aquifer Heterogeneity and Geochemical Variation on Petroleum-Hydrocarbon Biodegradation at a Gasoline Spill Site

2014 ◽  
Vol 1079-1080 ◽  
pp. 584-588 ◽  
Author(s):  
Po Jen Lien ◽  
Hsiao Jung Ho ◽  
Tzu Hsin Lee ◽  
Wen Liang Lai ◽  
Chih Ming Kao
Keyword(s):  
Land Surface ◽  
Petroleum Hydrocarbon ◽  
Microbial Population ◽  
Three Dimensional ◽  
Reduction Process ◽  
Hydrocarbon Biodegradation ◽  
Chemical Extraction ◽  
Small Scale ◽  
Spill Site

In subsurface environment, small-scale heterogeneities usually cause the reduction of the applicability of in situ remedial techniques. Biogeochemical heterogeneities and preferential groundwater flow paths create complex hydrogeologic conditions at most contaminated sites. A thorough understanding of the resulting three-dimensional distribution of contaminants is a necessity prior to determining a need for remediation. In this study, a gasoline spill site was selected to examine the effects of aquifer heterogeneities and geochemical variations on petroleum hydrocarbon biodegradation via different oxidation-reduction process. At this site, two multilevel sampling wells were installed to delineate the lateral (5 m) and vertical (0.5 m) distribution of contaminant concentrations and different biogeochemical parameters. Two 5-cm (I.D.) continuous soil cores [from 4 to 8 m below land surface (bls)] were collected within the gasoline plume to evaluate the distribution of the microbial population in soils. Results show that high microbial activities were observed in soil samples based on the following evidences: (1) high petroleum hydrocarbon degradation rate, and (2) high microbial biomass. Each soil section was used for chemical extraction, microbial enumeration, and grain size distribution. Results show that the soil sections with more permeable sediment materials corresponded with higher biomass (total anaerobes > 2 x 106cells/g) and significant contaminant degradation. However, those sections with less permeable sediments contained lower microbial population. Results indicate that the subsurface microorganisms were distributed unevenly in the aquifer, and some regions were devoid of microorganisms and biodegradation activities. Spatial distribution of microorganisms, soil materials, and biogeochemical characteristics in the subsurface soils control the extent and kinetics of contaminant biodegradation. Thus, using blended aquifer materials for measurement of in situ biodegradation rates may not achieve representative results.

scholarly journals Effect of thaws on snow cover and soil freezing under the contemporary climate change

2019 ◽  
Vol 59 (4) ◽  
pp. 475-482
Author(s):  
A. V. Sosnovsky ◽  
N. I. Osokin
Keyword(s):  
Thermal Resistance ◽  
Snow Cover ◽  
Thermal Protection ◽  
Soil Surface ◽  
Snow Accumulation ◽  
Cold Period ◽  
Soil Freezing ◽  
Wet Snow ◽  
Using Data ◽  
Liquid Precipitation

Thaw and liquid precipitation retard cooling of snow cover and soil surface and so may be a factor of heating. This slows down the soil freezing due to more active freezing of the wet snow, and, thus, promotes cooling and re-cooling of the soil. However, there are a number of factors which intensify the soil freezing after thaw. With thaw, the thickness of the snow cover decreases, and its density increases. In addition, after freezing wet snow improves the contact between the ice crystals, which increases the hardness and thermal conductivity of the snow. As a result, after the thaw, the thermal protection ability of the snow decreases, and this can accelerate freezing of the soil. The dynamics of snow accumulation in Russia is considered in the paper. Using data obtained in the Western Svalbard, we demonstrate the increase in the number of thaws and liquid precipitation and influence of them on the snow cover and soil freezing. The influence of thaw on the growth of thermal resistance of snow cover is also considered. Calculations have shown that in the absence of a thaw, the depth of soil freezing is 1.26 m. With a thaw lasting 10 days, which begins on the 40th day from the start of soil freezing, the depth of freezing is reduced down to 1.2 m without considering changes in snow cover. When taking into account changes in the thermal resistance of snow cover, the depth of soil freezing by the end of the cold period increases up to 1.32 cm. With a thaw in the mid-winter, i.e. on the 70th day, the depth of freezing decreases down to 1.22 m, that is smaller than the depth of freezing without thaw. This scenario is in accordance with changes in snow accumulation dynamics under the present-day climate, as in many areas most of the solid precipitation falls in the first half of the cold period. As a result, for a period after a thaw the smaller volume of snow will be deposited, and this will retard increasing in thermal resistance of the snow cover

scholarly journals Impact of Extreme Land Surface Heterogeneity on Micrometeorology over Spring Snow Cover

2017 ◽  
Vol 18 (10) ◽  
pp. 2705-2722 ◽  
Author(s):  
R. Mott ◽  
S. Schlögl ◽  
L. Dirks ◽  
M. Lehning
Keyword(s):  
Boundary Layer ◽  
Snow Cover ◽  
Land Surface ◽  
Internal Boundary Layer ◽  
Internal Boundary ◽  
Small Scale ◽  
Sensible Heat ◽  
Snow Surface ◽  
Boundary Layer Development ◽  
Layer Development

Abstract The melting mountain snow cover in spring typically changes from a continuous snow cover to a mosaic of patches of snow and bare ground, inducing an extreme heterogeneity of the land surface. A comprehensive measurement campaign, the Dischma experiment, was conducted during three entire ablation seasons. The aim of this study was to experimentally investigate the small-scale boundary layer dynamics over a melting snow cover with a gradually decreasing snow cover fraction and the associated heat exchange at the snow surface. This study presents a unique dataset combining eddy covariance measurements at different atmospheric levels with maps of snow surface temperatures and snow cover fractions. The experiments evidence diurnal mountain wind systems driving the diurnal cycle of turbulent sensible heat fluxes over snow and the formation of katabatic flows over long-lasting snow patches strongly affecting the temporal evolution of snow surface temperature patterns. The snow cover distribution is also shown to be of vital importance for the frequency of stable internal boundary layer development over snow. For situations with a clear evidence of stable internal boundary layer development over snow, the data reveal a very shallow atmospheric layer adjacent to the snow cover decoupled from the warm-air advection above. These measurements confirm previous wind tunnel experiments that also evidenced a decoupling of the air adjacent to the snow cover from the warmer air above, especially within topographical depressions and when ambient wind velocities are low. For these situations, in particular, all tested energy balance models strongly overestimated the turbulent sensible heat flux directed toward the snow cover.

Effects of Spatial Aggregation of Initial Conditions and Forcing Data on Modeling Snowmelt Using a Land Surface Scheme

2008 ◽  
Vol 9 (4) ◽  
pp. 789-803 ◽  
Author(s):  
Pablo F. Dornes ◽  
John W. Pomeroy ◽  
Alain Pietroniro ◽  
Diana L. Verseghy
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Large Scale ◽  
Initial Conditions ◽  
Model Performance ◽  
Surface States ◽  
Snow Accumulation ◽  
Yukon Territory ◽  
Small Scale ◽  
Topographic Effects

Abstract Small-scale topography and snow redistribution have important effects on snow-cover heterogeneity and the timing, rate, and duration of spring snowmelt in mountain tundra environments. However, land surface schemes (LSSs) are usually applied as a means to provide large-scale surface states and vertical fluxes to atmospheric models and do not normally incorporate topographic effects or horizontal fluxes in their calculations A study was conducted in Granger Creek, an 8-km2 catchment within Wolf Creek Research Basin in the Yukon Territory, Canada, to examine whether inclusion of the effects of wind redistribution of snow between landscape units, and slope and aspect in snowmelt calculations for tiles, could improve the simulation of snowmelt by an LSS. Measured snow accumulation, reflecting overwinter wind redistribution of snow, was used to provide initial conditions for the melt simulation, and physically based algorithms from a small-scale hydrological model were used to calculate radiation on slopes during melt. Based on consideration of the spatial distribution of snow accumulation, topography, and shrub cover in the basin, it was divided into five landscapes units (tiles) for simulation of mass and energy balance using an LSS during melt. Effects of averaging initial conditions and forcing data on LSS model performance were contrasted against distributed simulations. Results showed that, in most of the cases, simulations using aggregated initial conditions and forcing data gave unsuccessful descriptions of snow ablation whereas the incorporation of both snow-cover redistribution and slope and aspect effects in an LSS improved the prediction of snowmelt rate, timing, and duration.

scholarly journals Small-scale variation of snow in a regional permafrost model

2015 ◽  
Vol 9 (6) ◽  
pp. 6661-6696
Author(s):  
K. Gisnås ◽  
S. Westermann ◽  
T. V. Schuler ◽  
K. Melvold ◽  
B. Etzelmüller
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Ground Temperature ◽  
Small Scale ◽  
Spatial Average ◽  
Near Surface ◽  
Ground Temperatures ◽  
Grid Approach ◽  
Realistic Representation ◽  
Strong Winds

Abstract. The strong winds prevalent in high altitude and arctic environments heavily redistribute the snow cover, causing a small-scale pattern of highly variable snow depths. This has profound implications for the ground thermal regime, resulting in highly variable near-surface ground temperatures on the meter scale. Asymmetric snow distributions combined with the non-linear insulating effect of snow also mean that the spatial average ground temperature in a 1 km2 area can not necessarily be determined based on the average snow cover for that area. Land surface or permafrost models employing a coarsely classified average snow depth will therefore not yield a realistic representation of ground temperatures. In this study we employ statistically derived snow distributions within 1 km2 grid cells as input to a regional permafrost model in order to represent sub-grid variability of ground temperatures. This is shown to improve the representation of both the average and the total range of ground temperatures: the model results show that we reproduce observed sub-grid ground temperature variations of up to 6 °C, with 98 % of borehole observations within the modelled temperature range. Based on this more faithful representation of ground temperatures, we find the total permafrost area of mainland Norway to be nearly twice as large as what is modelled without a sub-grid approach.

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