The relation of snow transparency to density and air permeability in a natural snow cover

1971 ◽  
Vol 76 (30) ◽  
pp. 7385-7388 ◽  
Author(s):  
James D. Bergen
Keyword(s):  
Snow Cover ◽  
Air Permeability ◽  
Natural Snow

scholarly journals A Possible Relation Between Grain Size, Density, and Light Attenuation in Natural Snow Cover

1970 ◽  
Vol 9 (55) ◽  
pp. 154-156
Author(s):  
James D. Bergen
Keyword(s):  
Grain Size ◽  
Porous Medium ◽  
Specific Surface ◽  
Snow Cover ◽  
Extinction Coefficient ◽  
Light Attenuation ◽  
Empirical Relation ◽  
Air Permeability ◽  
Fair Agreement ◽  
Natural Snow

AbstractThe extinction coefficient for the transmission of light through snow cover is related to the grain size and density of the snow cover. The connection is made by means of an empirical relation between the latter parameters and the air permeability and by the Carmen–Kozney relation between the air permeability and specific surface of a porous medium. The results are compared with a set of measurements found in the literature with fair agreement between the predicted and measured values of the extinction coefficient.

scholarly journals A Possible Relation Between Grain Size, Density, and Light Attenuation in Natural Snow Cover

1970 ◽  
Vol 9 (55) ◽  
pp. 154-156 ◽  
Author(s):  
James D. Bergen
Keyword(s):  
Grain Size ◽  
Porous Medium ◽  
Specific Surface ◽  
Snow Cover ◽  
Extinction Coefficient ◽  
Light Attenuation ◽  
Empirical Relation ◽  
Air Permeability ◽  
Fair Agreement ◽  
Natural Snow

Abstract The extinction coefficient for the transmission of light through snow cover is related to the grain size and density of the snow cover. The connection is made by means of an empirical relation between the latter parameters and the air permeability and by the Carmen–Kozney relation between the air permeability and specific surface of a porous medium. The results are compared with a set of measurements found in the literature with fair agreement between the predicted and measured values of the extinction coefficient.

Frost heaving in a boreal soil in relation to soil scarification and snow cover

2001 ◽  
Vol 31 (6) ◽  
pp. 1084-1092 ◽  
Author(s):  
Urban Bergsten ◽  
France Goulet ◽  
Tomas Lundmark ◽  
Mikaell Ottosson Löfvenius
Keyword(s):  
Snow Cover ◽  
Field Experiments ◽  
Soil Surface ◽  
Control Treatment ◽  
Tree Seedlings ◽  
Frost Heaving ◽  
Humus Layer ◽  
Soil Scarification ◽  
Natural Snow ◽  
Surface Ice

Vertical uplift of seedlings and rods on the soil surface and at a depth of 5 cm, and of reference trees, was monitored using a theodolite from autumn to spring in two adjacent field experiments on a silt soil in northern Sweden. Treatments involving scarification (control and square patches of 0.1, 0.2, 0.4, and 0.8 m at natural snow cover) and snow cover (simulated maximum cover, snow free, and natural cover for control and 0.4-m patches) were compared. For snow free and natural snow cover, diurnal variation of soil surface temperature, duration and magnitude of freezing temperatures, and uplift increased with patch size. At the end of the winter under natural snow cover, uplift of the soil surface and shallow soil was between 4.4 and 5.3 cm for the control treatment without scarification and the 0.1-m patch while the uplift for the 0.4- and 0.8-m patches reached 7.6–11.5 cm. The highest uplift value, 14.6 cm, was observed for the snow-free treatment with 0.4-m patches. Maximum uplift of trees averaged 4.4 cm, which was similar to values observed for seedlings and rods with an intact humus layer and a natural snow cover, indicating that the highest observed uplift was mainly due to needle and soil surface ice. In conclusion, size of the scarified area and duration and thickness of snow cover largely influence frost heaving of tree seedlings in a susceptible soil.

Point physical model of movement of ions through natural snow cover

2000 ◽  
Vol 235 (3-4) ◽  
pp. 170-182 ◽  
Author(s):  
T Iida ◽  
K Ueki ◽  
H Tsukahara ◽  
A Kajihara
Keyword(s):  
Snow Cover ◽  
Physical Model ◽  
Natural Snow

Evaluation of the productivity of the hybrid vine Seyval blanc in function of several types of protection against frost in Quebec

OENO One ◽  
2003 ◽  
Vol 37 (1) ◽  
pp. 1
Author(s):  
T. Telebak ◽  
Yvon Jolivet ◽  
Jean-Marie Dubois
Keyword(s):  
Mortality Rate ◽  
Snow Cover ◽  
Sugar Content ◽  
Winter Season ◽  
Ambient Air ◽  
Bare Soil ◽  
Climatic Conditions ◽  
The Other ◽  
Potential Yield ◽  
Natural Snow

<p style="text-align: justify;">In Quebec, winter frost is one of the determining factors influencing vine survival and yield. To evaluate the quality of the different types of winter protection, ground temperature data under different covers (ground knolls, leaf mounds, carried over snow and natural snow) and ambient air temperatures were recorded. Results show that the Seyval blanc, if not protected against winter frost, can sustain quite serious damages when the air temperature reaches -30 °C. Ridging, leaf covering and the natural snow cover as well as carried over snow have a positive effect on ground temperatures, since over the site without protection, frost penetrated down to a depth of 50 cm. However, it seems that the root System did not sustain significant damages from the ground frost since regrowth occurred in the Spring. Because of its direct exposure to radiation and surface climatic conditions, bare soil warms up more quickly in the Spring compared to the other sites benefiting from protection. Results also indicate that the mortality rate of the vine stock fruit buds without protection is nearly 100 % compared to the protected vine stocks with a fruit bud mortality rate varying from 22.5 to 35.8 %. The protected vine stocks, regardless of the type of protection used, had satislactory yields from 7.2 t/ha to 24.4 t/ha. On the other hand, the raisin yield of the vine stocks without any winter protection is null. The best raisin yields were obtained over sites where vine stocks were protected by ridging (40 cm of earth), while the vine stocks protected by leaf covering showed an average yield. We also observed that when vine stock leaf covering is coupled with lodged vine shoots, raisin yields are higher than when the vine shoots are erect. However, in both cases, potential yield per hectare is satisfactory. Hence, the lodging of vine shoots becomes a useless operation. The vine stocks protected by natural snow as well as by leaf covering (30 cm + carried over snow and lodged vine shoots) gave the fruit with the highest sugar content. Snow is also an excellent insulator because a 37 cm high snow cover permitted the survival of the vine stocks protected by snow even when the temperature reached -30 °C. The only problem still posing a threat is snow cover variability during the winter season. A reduced snow cover, coupled with temperature conditions under the threshold of tolerance of the vine to cold, could not insure satisfactory protection ol the fruit buds.</p>

Future Climate Change in the European Alps

2020 ◽  
Author(s):  
Andreas Gobiet ◽  
Sven Kotlarski
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Precipitation Extremes ◽  
Convective Precipitation ◽  
Future Climate Change ◽  
European Alps ◽  
Strong Wind ◽  
Alpine Area ◽  
Natural Snow ◽  
Precipitation Changes

The analysis of state-of-the-art regional climate projections indicates a number of robust changes of the climate of the European Alps by the end of this century. Among these are a temperature increase in all seasons and at all elevations and a significant decrease in natural snow cover. Precipitation changes, however, are more subtle and subject to larger uncertainties. While annual precipitation sums are projected to remain rather constant until the end of the century, winter precipitation is projected to increase. Summer precipitation changes will most likely be negative, but increases are possible as well and are covered by the model uncertainty range. Precipitation extremes are expected to intensify in all seasons. The projected changes by the end of the century considerably depend on the greenhouse-gas scenario assumed, with the high-end RCP8.5 scenario being associated with the most prominent changes. Until the middle of the 21st century, however, it is projected that climate change in the Alpine area will only slightly depend on the specific emission scenario. These results indicate that harmful weather events in the Alpine area are likely to intensify in future. This particularly refers to extreme precipitation events, which can trigger flash floods and gravitational mass movements (debris flows, landslides) and lead to substantial damage. Convective precipitation extremes (thunderstorms) are additionally a threat to agriculture, forestry, and infrastructure, since they are often associated with strong wind gusts that cause windbreak in forests and with hail that causes damage in agriculture and infrastructure. Less spectacular but still very relevant is the effect of soil erosion on inclined arable land, caused by heavy precipitation. At the same time rising temperatures lead to longer vegetation periods, increased evapotranspiration, and subsequently to higher risk of droughts in the drier valleys of the Alps. Earlier snowmelt is expected to lead to a seasonal runoff shift in many catchments and the projected strong decrease of the natural snow cover will have an impact on tourism and, last but not least, on the cultural identity of many inhabitants of the Alpine area.

scholarly journals Changes in Snow Depth, Snow Cover Duration, and Potential Snowmaking Conditions in Austria, 1961–2020—A Model Based Approach

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1330
Author(s):  
Marc Olefs ◽  
Roland Koch ◽  
Wolfgang Schöner ◽  
Thomas Marke
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Climate Impact ◽  
Physically Based ◽  
Spatially Distributed ◽  
Direct Interpretation ◽  
H 26 ◽  
Natural Snow ◽  
Snow Cover Duration ◽  
Snow Conditions

We used the spatially distributed and physically based snow cover model SNOWGRID-CL to derive daily grids of natural snow conditions and snowmaking potential at a spatial resolution of 1 × 1 km for Austria for the period 1961–2020 validated against homogenized long-term snow observations. Meteorological driving data consists of recently created gridded observation-based datasets of air temperature, precipitation, and evapotranspiration at the same resolution that takes into account the high variability of these variables in complex terrain. Calculated changes reveal a decrease in the mean seasonal (November–April) snow depth (HS), snow cover duration (SCD), and potential snowmaking hours (SP) of 0.15 m, 42 days, and 85 h (26%), respectively, on average over Austria over the period 1961/62–2019/20. Results indicate a clear altitude dependence of the relative reductions (−75% to −5% (HS) and −55% to 0% (SCD)). Detected changes are induced by major shifts of HS in the 1970s and late 1980s. Due to heterogeneous snowmaking infrastructures, the results are not suitable for direct interpretation towards snow reliability of individual Austrian skiing resorts but highly relevant for all activities strongly dependent on natural snow as well as for projections of future snow conditions and climate impact research.

scholarly journals An analysis of compressive strain in adjacent temperature-gradient and equi-temperature layers in a natural snow cover

1980 ◽  
Vol 26 (94) ◽  
pp. 283-289 ◽  
Author(s):  
Richard L. Armstrong
Keyword(s):  
Strain Rate ◽  
Snow Cover ◽  
Compressive Strain ◽  
Coarse Grained ◽  
Adjacent Layer ◽  
Dominant Type ◽  
Fine Grained ◽  
Order Of Magnitude ◽  
Alpine Research ◽  
Natural Snow

AbstractCompressive strain-rates in discrete layers of a sub-alpine snow cover are analyzed. Individual layers are identified according to density and the dominant type of metamorphism which contributed to their formation. Data were collected during four winter seasons at the Institute of Arctic and Alpine Research (INSTAAR) snow-study site (3 400 m), Red Mountain Pass, south-western Colorado, U.S.A. At average densities of less than 250 kg m₋3the influence of metamorphism on strain-rate is not apparent. However, at densities greater than 250 kg m₋3, two separate relationships emerge for strain as a function of crystal type and density. While two adjacent layers may exhibit comparable densities, a layer of sintered, fine grained (ET) snow indicates a strain-rate approximately one order of magnitude greater than an adjacent layer of cohesionless, coarse-grained (TG) snow.

scholarly journals Spatial Variability of Shortwave Irradiance for Snowmelt in Forests

2008 ◽  
Vol 9 (6) ◽  
pp. 1482-1490 ◽  
Author(s):  
John Pomeroy ◽  
Chad Ellis ◽  
Aled Rowlands ◽  
Richard Essery ◽  
Janet Hardy ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Spatial Variation ◽  
Snow Cover ◽  
Boreal Forests ◽  
Stand Structure ◽  
Snow Accumulation ◽  
Snow Covered Area ◽  
Covered Area ◽  
Depletion Curve ◽  
Natural Snow

Abstract The spatial variation of melt energy can influence snow cover depletion rates and in turn be influenced by the spatial variability of shortwave irradiance to snow. The spatial variability of shortwave irradiance during melt under uniform and discontinuous evergreen canopies at a U.S. Rocky Mountains site was measured, analyzed, and then compared to observations from mountain and boreal forests in Canada. All observations used arrays of pyranometers randomly spaced under evergreen canopies of varying structure and latitude. The spatial variability of irradiance for both overcast and clear conditions declined dramatically, as the sample averaging interval increased from minutes to 1 day. At daily averaging intervals, there was little influence of cloudiness on the variability of subcanopy irradiance; instead, it was dominated by stand structure. The spatial variability of irradiance on daily intervals was higher for the discontinuous canopies, but it did not scale reliably with canopy sky view. The spatial variation in irradiance resulted in a coefficient of variation of melt energy of 0.23 for the set of U.S. and Canadian stands. This variability in melt energy smoothed the snow-covered area depletion curve in a distributed melt simulation, thereby lengthening the duration of melt by 20%. This is consistent with observed natural snow cover depletion curves and shows that variations in melt energy and snow accumulation can influence snow-covered area depletion under forest canopies.

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