Snow Cover Depth Research Articles

Global distribution of snow avalanches and changing activity in the Northern Hemisphere due to climate change

Snow avalanches occur in the mountains of all continents and climatic zones. The lower boundary of avalanche distribution rises from sea level in polar and temperate zones to 6000 m in the tropics. Four altitudinal belts of avalanching are distinguished: (I) permanent snow; (II) stable seasonal snow cover; (III) unstable snow cover; and (IV) rare snowfalls. Most avalanche-danger areas of the world belong to the stable seasonal snow-cover bell. Using data from a GFDL Q-flux Model, we estimated possible changes of the main characteristics of the avalanche regime in the Northern Hemisphere: depth of snow cover, duration of the avalanche-prone period and number of days with avalanche-prone snowfalls. At the beginning of the twenty-first Century, there will likely be a smoothing of the sharp differences in avalanche activity between various mountain regions of the World. Avalanche activity should be less in the most active regions and it is likely to increase in regions with low avalanche activity.

Global distribution of snow avalanches and changing activity in the Northern Hemisphere due to climate change

Snow avalanches occur in the mountains of all continents and climatic zones. The lower boundary of avalanche distribution rises from sea level in polar and temperate zones to 6000 m in the tropics. Four altitudinal belts of avalanching are distinguished: (I) permanent snow; (II) stable seasonal snow cover; (III) unstable snow cover; and (IV) rare snowfalls. Most avalanche-danger areas of the world belong to the stable seasonal snow-cover bell.Using data from a GFDL Q-flux Model, we estimated possible changes of the main characteristics of the avalanche regime in the Northern Hemisphere: depth of snow cover, duration of the avalanche-prone period and number of days with avalanche-prone snowfalls. At the beginning of the twenty-first Century, there will likely be a smoothing of the sharp differences in avalanche activity between various mountain regions of the World. Avalanche activity should be less in the most active regions and it is likely to increase in regions with low avalanche activity.

Inorganic nitrogen and microbial biomass dynamics before and during spring snowmelt

Recent work in seasonally snow covered ecosystems has identified thawed soil and high levels of heterotrophic activity throughout the winter under consistent snow cover. We performed measurements during the winter of 1994 to determine how the depth and timing of seasonal snow cover affect soil microbial populations, surface water NO 3 loss during snowmelt, and plant N availability early in the growing season. Soil under early accumulating, consistent snow cover remained thawed during most of the winter and both microbial biomass and soil inorganic N pools gradually increased under the snowpack. At the initiation of snowmelt, microbial biomass N pools increased from 3.0 to 5.9 g N m 2 , concurrent with a decrease in soil inorganic N pools. During the latter stages of snowmelt, microbial biomass N pools decreased sharply without a concurrent increase in inorganic N pools or significant leaching losses. In contrast, soil under inconsistent snow cover remained frozen during most of the winter. During snowmelt, microbial biomass initially increased from 1.7 to 3.1 g N m 2 and then decreased as sites became snow-free. In contrast to smaller pool sizes, NO 3 export during snowmelt from the inconsistent snow cover sites of 1.14 ( 0.511) g N m 2 was significantly greater ( p 0.001) than the 0.27 ( 0.16) g N m 2 exported from sites with consistent snow cover. These data suggest that microbial biomass in consistently snow-covered soil provides a significant buffer limiting the export of inorganic N to surface water during snowmelt. However, this buffer is very sensitive to changes in snowpack regime. Therefore, interannual variability in the timing and depth of snowpack accumulation may explain the year to year variability in inorganic N concentrations in surface water these ecosystems.

Meteorological Conditions and Clay Characteristics in the Hachimantai Sumikawa Hot Spa Landslide/Mud Flow Disasters

Snow melt meteorological conditions and landslide clay characteristics were investigated regarding the Hachimantai Sumikawa hot spa landslide/mud flow disasters occurred at the beginning of May, 1997. Factors affecting for landslides in the snowy regions are generally attributed to snow cover depth, melting snow and heavy rainfall. The main triggers of the prsent topic under debate natural disasters were also considered to be a heavy rainfall ahead of the appearance of the disasters and a continuous snow melting phenomenon.On the other hand, landslide clay samples were taken from the Sumikawa landslide area, and several soil tests were performed to investigate the physical and mechanical characteristics. Two types of clay were found at the Sumikawa river site along the trace of landslide, and the main clay mineral of the clay samples were analyzed as Kaolin clay by X-ray powder diffraction patterns. According to the soil tests, the softer clay is considered to be a conductive clay to the landslide because of its high water content, low residual shear strength, and high liquid limit.

An investigation of the spatial association between snow depth and topography in a Prairie agricultural landscape using digital terrain analysis

The association of snowcover depth with topography and land cover was examined for a 1.5 km 2 agricultural site in the Canadian Prairies. Topography was quantified by a suite of general geomorphometric variables that were measured directly by the analysis of a raster digital elevation model (DEM) with a 10 m grid cell size. These variables expressed local surface morphology and relative topographic position. The major land covers represented in the study area were wheat stubble and summerfallow. Point observations of snow depth at the site were obtained near the time of peak snow accumulation and during melt. Initial analysis was made of scatterplots and correlations between snow depth and individual topographic variables. These correlations were weak but illustrated that, at the local scale, snow depth patterns cannot be adequately modelled through simple bivariate relationships with topographic variables. The correlations also showed that snow depth is more strongly related to relative topographic position variables than to variables expressing local surface morphology. Subsequent analysis involved a divisive subdivision of the study site into six terrain units defined in terms of several relative topographic position and land cover variables. The units were used to model the spatial patterns of snow depth that occurred during the observed snowcover situations. Although the terrain classification only reduced the total snow depth variance by approximately 30%, it delineated the major patterns of snow depth observed over the study area and elucidated the spatial relationships between snowcover depth and landscape attributes.

MEASUREMENT OF FROST-INDUCED SNOWMELT RUNOFF IN A FOREST SOIL

Snow interception in a coniferous stand leads to considerable short-range variability in snowcover depth, which in turn affects the water and heat regime of the soil. To study the coupling between snow accumulation, frost penetration, and hydrological response, plot-scale experiments were conducted in a subalpine spruce forest. The stony, sandy-loamy Spodosol was highly permeable and had an organic layer of 5-15 cm thickness. Within two plots, one underneath a tree crown and one in a canopy gap, we measured near-surface runoff, soil temperature, and liquid water content. Snow and frost depths varied more in space than between two winter periods at given locations. Frost penetration was greater near the trunk, where a higher portion of snowmelt water drained downslope close to the surface than in the gap due to frost-induced reduction of infiltration. In both years, the spring snowmelt occurred over two distinct periods. During the first snowmelt, the water percolated primarily through the frozen layer and part of it probably refroze within the frozen layer, thereby raising the total water and ice content. During the second event, near-surface runoff was more pronounced.

Temperature Effects of Passive Greenhouse Apparatus in High-Latitude Climate Change Experiments

1. Passive greenhouse apparatus is commonly used to investigate the in situ biological response of terrestrial communities to global warming. 2. Although close conformity of greenhouse treatment effects to general circulation model (GCM) scenarios is widely claimed, no proof of such a relationship has yet been published. 3. Here, the relationship between passive greenhouse thermal environment and future climate conditions is considered using temperature data collected from within and without greenhouses deployed in the maritime Antarctic. It is revealed that in terms of thermal extremes, diel and annual variation, and overall distribution across the temperature spectrum, such apparatus achieves only poor simulation of GCM forecasts. 4. During summer, greenhouses induce an amplified daily range of temperatures, elevated maxima and accelerated rates of change. 5. During spring and autumn, diel temperature variation continues inside the green-houses while snow cover protects the controls. 6. During winter, an inverse treatment effect occurs, in which the relative depth of snow cover causes lower temperatures in greenhouses than in controls. 7. These treatment effects differ significantly from GCM climate predictions. Changes recorded in the composition, structure and function of greenhouse biota may thus be artefacts of the methodology. 8. Thorough a priori testing of greenhouse treatment effects is recommended for future climate change studies that are to be conducted in environments subject to seasonal snowfall, solar elevation and day length

降雪の酸性度と積雪、融雪過程を通しての変動特性

This study is concerned with the characteristics of acidity of snowfalls brought by the northwesterly winter monsoons, low pressure systems and other disturbances around Sapporo, Hokkaido, Japan. Samplings of daily snowfalls were carried out from January 1 to March 31, 1991 in Sapporo. Falling snow crystals, whole depth of snow cover, depth of snow layers formed by each snowfall, and snowmelt water existing snow cover were measured through a period of accumulation and melting of snow cover. Snowfalls brought by the northwesterly winter monsoon winds had relatively lower pH values and higher electrical conductivity than those brought by low pressure systems. The acidity of the whole depth of snow cover did not vary greatly before the snowmelt period. The acidity of each snow layer, however, indicated characteristic variations closely connected with metamorphism of the accumulated snow cover. During the observation period, the acidity of daily snowmelt water which had run off from snow cover showed the greatest ion concentrations in the first stage of the snowmelt season. Concentrations of chemical constituents of snow cover had drastically decreased and acidity had approached neutrality at the peak of the snowmelt season. The cause of this seems to be the large quantity of chemical constituents which run off snow cover for a short time during the first stage of the snowmelt season.

DIGITAL PHOTOGRAMMETRIC MODELING OF MOUNTAINOUS TERRAIN AND SNOW COVER DISTRIBUTION PATTERNS

This paper explores applications of digital photogrammetric modeling of mountainous terrain in forecasting snow depth and the meltwater avalanche hazard in a mining region of northwestern Russia. A series of initial maps (initial terrain points, relief of snow-flow centers, slope angles and orientations) provides successively more specific information, culminating in the compilation of a map of maximum snow cover depths at a center of water-saturated snow flows (representative reference site) on the northern slope of Mt. Aykuayvenchorr. Translated by Edward Torrey, Alexandria, VA 22308 from: Geomorfologiya, 1993, No. 3, pp. 75-83.

Concentration of CO2 under snow cover and the winter activity of the snow blight fungus Phacidium infestans

AbstractThe winter activity of soil organisms and of the fungus Phacidium infestans inoculated on excised Scots pine shoots was monitored by measuring CO2 concentrations under the snow cover. Other variables measured, relating to respiration, were the temperature under the shoot heaps and the depth of snow cover. The concentrations were highest when the temperature under the snow remained at a relatively high level during the whole winter which also favoured respiration from P. infestans. When the soil was covered with a thin layer of snow, the conditions did not favor a high respiration rate until the snow melt period.

MAPPING THE AVALANCHE HAZARD FOR MOUNTAINOUS AREAS OF AFGHANISTAN

The authors describe a procedure for the compilation of maps of the avalanche hazard in high-mountain regions of Afghanistan. The basic sources of information include space imagery (photographs and scanner imagery), weather station data, and other geographic information on relief, elevation, location of moisture sources, etc. The methodology features the compilation of series of increasingly more specific and informative maps and graphs regarding the avalanche hazard: terrain types, snow cover depth and seasonal extent, duration of snow cover and its elevational zonation, snow as a factor in avalanche formation, and summary map of avalanche hazard. Translated by Elliott B. Urdang, Providence, RI 02906 from: Materialy glyatsiologicheskikh issledovaniy, 1991, No. 71, pp. 86–93.

Considerations on Snowdrift on Roof Surface

An outdoor experiment is conducted to investigate snowdrift that has much effect on the formation of snow cover depth on roof surface. Three types of model roof with respective roof levels and on existent roof are used to measure changes in snow cover depth and snowdrift with time. At the same time, the wind velocity, temperature and snow cover depth above the ground are measured. The levels of the existent roof surface ranges from 9 to 12 m. The results of this experiment are obtained as follws :1) The higher the roof surface, the more the snowdrift. Snow cover depth on a roof is less than that on the ground.2) Snowdrift on a roof is more likely to occur than that on the ground, because the surface wind has a vertical distribution, which increases in value with height.3) The larger the roof surface is, the more the amount of snowdrift becomes when the wind blows hard. Hence, as roofs increase in area, the distribution of snow cover has become more ununiform.

積雪中における押し出し流の形成

Translatory flow is observed in a ground water runoff during a rainstorm. Layered snow cover is considered to play the same role as soil layer for water runoff. The purpose of this paper is to report the translatory flow phenomena of snow meltwater in a snowpack. Studies on the snowmelt runoff in a snowpack were carried out at eastern Canada and Hokkaido. In the case of Canada, the hydrograph of snowmelt is separated into “old water” (meltwater in the lower snowpack) and “new water” (meltwater percolated from surface snow layer) by the concentration of NO3-. The concentration of NO 3- in meltwater in the lower snowpack is estimated to be higher than that in meltwater generated from the surface snow layer. Separated “old water” is the major component of early snowmelt runoff during a day. This quick response of the meltwater in the lower snowpack requires a translatory flow mechanism in the snowpack. “New water” is the major component of the recession limb of the hydrograph. The same phenomena were observed at Moshiri, Hokkaido, during the 1988 snowmelt. Two peaks on the meltwater hydrograph were observed. The first peak is composed of the meltwater in the lower snowpack; the major component of the second peak is the meltwater percolated from the surface snow layer. The translatory phenomenon in a snowpack is not observed when the depth of snow cover is not so thick.

Performance of an ultrasonic level sensing system for automated monitoring of snowcover depth

The operating characteristics of a commercially available ultrasonic level measuring system is described. The objective was to test the applicability of the system to automatically monitor depths of snowcover as part of a fully automated weather station. With temperature compensation, the system is relatively stable when the time rate of change in temperature is below 8°C h −1, a value that rarely occurs in the natural environment. Measured depths are relatively unaffected by relative humidity, wind velocity, and rain. Spatial average of snow-cover depths measured with the system at seven locations compared favourably with that measured with snow rulers, with a correlation coefficient greater than 0.95. Using three standard deviation limits, the imprecision of the system as compared with the snow rulers is ±0.72 cm . A simple electro-mechanical scanner was used to interface sonic transducers to a single electronic measuring unit. With such an interface, additional point measurement of snowcover depth may be achieved with a relatively small amount of added cost. Low cost together with accuracy and reliability makes this system very attractive for use in automatic weather observations in agricultural and forestry applications.

Climate and energy exchange at the snow surface in the Alpine Region of the Sierra Nevada: 1. Meteorological measurements and monitoring

A detailed evaluation of climate conditions in a small alpine watershed, typical of much of the southern Sierra Nevada, is presented for the 1986 water year. Measurements of snowfall, meteorological and snow cover conditions, and snow cover ablation are used to characterize the climate at four locations in the watershed during that snow season. Data from these locations are then combined into two representative sites for the watershed. Measurement approaches and methodologies and the effectiveness of instrumentation used in the study are discussed, and an estimate of the uncertainty of the monitored meteorological parameters is made. The data are integrated into a continuous hourly time series of solar and thermal radiation, air, snow and soil temperature, humidity, and wind at the two representative sites in this remote alpine watershed for an entire snow season. Snow deposition and snow cover depth and density are measured manually at regular intervals throughout the snow season. While problems were encountered monitoring air and snow surface temperature, humidity, and wind, because of the extreme conditions which are likely to occur in an alpine environment, radiation is easily monitored, and the estimated uncertainty of all measured parameters was acceptably low. This effort was required to develop a high quality time series of integrated climate data to evaluate the components of the energy balance of the snow cover during both deposition and ablation conditions.

A Postfire Shift From Lichen‐Spruce to Lichen‐Tundra Vegetation at Tree Line

The environmental changes associated with a fire—induced shift from old—growth lichen—spruce krummholz to lichen—tundra vegetation have been evaluated at a tree line site in northern Quebec. Tree ring and growth form patterns of black spruce (Picea mariana) remains lying on the ground in a lichen—tundra community were used to reconstruct, within a 4600—m2 quadrat, the structure of a conifer stand at the time of the burn (°AD 1750). The prefire spruces were the last members of a long regenerative sequence leading to maintenance of a lichen—spruce stand formed after a burn °1700 yr BP. At this time postfire recruitment was most likely facilitated by a favorable climatic conditions. Before the 1750 fire event the krummholz was predominantly maintained by layering, due to severe climatic conditions at least since the beginning of the Little Ice Age (°AD 1580). The site was deforested by the 1750 fire, because of the limited regenerative potential of stunted spruce. Postfire spruce exclusion has been responsible for major environmental changes associated with a thinner snow cover. Along the border of the deforested site snow cover depth was controlled by living spruces, whereas postfire shrubs (mostly dwarf birch, Betula glandulosa) of the lichen—tundra stand were unable to trap drifting snow. A significant decrease in thickness of the snow cover following deforestation was deduced from a comparative analysis of stem morphology of prefire spruces and present snow conditions. Inception of gelifluction lobes and mudboils was also caused by a change in the soil thermal regime associated with a reduced snow cover. Our results confirm the hypothesis that several lichen stands of the forest—tundra are postfire communities succeeding from degraded conifer stands during cold periods of the late Holocene.

Wolf predation and snow cover as mortality factors in the ungulate community of the Bialowieża National Park, Poland.

Wolf-ungulate interactions were studied in the pristine deciduous and mixed forests of the Bialowieża National Park in 1985-1989. The study period included two severe and two mild winters. The community of ungulates inhabiting Bialowieża National Park consisted of red deer Cervus elaphus, 55% of all ungulates; wild boar Sus scrofa, 42%; and roe deer Capreolus capreolus, moose Alces alces, and European bison Bison bonasus, about 1% each. The average size of red deer groups increased from 2.7 (SD 2.35) in spring and summer to 6.9 (SD 6.84) in autumn and winter. In winter the group size of red deer was positively correlated with the depth of snow cover and negatively correlated with the mean daily temperature. Average group size of wild boar did not change significantly between seasons; it was 6.8 (SD 5.16) in spring and summer and 5.7 (SD 4.67) in autumn and winter. Analysis of 144 wolf scats showed that wolves preyed selectively on red deer. In October-April, Cervidae (mostly red deer) constituted 91% of biomass consumed by wolves, while wild boar made up only 8%. In May-September deer formed 77% of prey biomass, and the share of wild boar increased to 22%. In all seasons of the year wolves selected juveniles from deer and boar populations: 61% of red deer and 94% of wild boar of determined age recovered from wolves' scats were young <1 year old. Analysis of 117 carcasses of ungulates found in Bialowieża National Park showed that predation was the predominant mortality factor for red deer (40 killed, 10 dead from causes other than predation) and roe deer (4 killed, none dead). Wild boar suffered most from severe winter conditions (8 killed, 56 dead). The percentage of ungulates that had died from undernutrition and starvation in the total mortality was proportional to the severity of winter.

Air Temperature and Radiation Depressions Associated with a Snow Cover

An analysis of air temperature and radiation regimes an days with and without a snow cover at the St. Paul, Minnesota, climatological observatory was made based on a 16 December-15 March 23-yr temperature record and a solar and longwave radiation record for 11 of those 23 years. In addition, an overlapping 41-yr temperature record of the Minneapolis-St. Paul National Weather Service Station (MSP) was analyzed for corroboration of the St. Paul temperature results. It was found that both the average maximum and average minimum air temperatures for winter days with a 10-cm or greater snow cover were 8.4°C lower than on the snow-free days. For days with intermediate-depth snow (>0 and <10 cm deep) the depressions of the maximum and minimum temperatures averaged about 2°C less. The temperature depressions at MSP were about 2°C less than at St. Paul for both snow-cover depths, a difference believed to be due to the more urban surroundings at MSP. A difference in the depression of the winter month temperatures was observed at MSP but not at the St. Paul observatory. The St. Paul results were unexpected, since it has been suggested that a greater maximum temperature depression, due to a higher sun, would occur in March than in December. The air temperature depressions compare favorably with the mean 16 December- 15 March radiometrically determined surface temperatures, which indicated that the intermediate snow depth and the ⩾10-cm snow depth were 1O° and 15°C, respectively, colder than the surface free of snow. The mean longwave radiation loss was 3.94 MJ m−2 day−1 greater from the snow-free surface than from a 10-cm or greater snow cover.

The role of passive microwaves in characterizing snow cover in the Colorado river basin

Snow cover and snow depth data acquired from meteorological stations and SNOTEL sites in the Colorado river basin of the western US were compared and correlated with brightness temperatures observed by passive microwave sensors. The ground data and satellite data were plotted onto 1/4o latitude by 1/4o longitude grids for the month, January through April and for the years 1979–1986. Results show that correlations were higher when sub-basin areas of the Colorado river were used rather than the entire Colorado river basin, because snow conditions in these areas are more likely to be similar. Multiple regression analysis using, in addition to the microwave data, input on surface roughness and elevation, vegetation and air temperature considerably improved the goodness of fit. Maximum and minimum temperatures were used as surrogates for grain size distributions. Multiple regression correlation coefficients for the eight sub-basin areas studied ranged between 0.49 and 0.86 for all years lumped together. When the regressions were run for individual years to reduce internannual variability of snow conditions, the average correlation coefficients ranged from 0.58–0.91 for the eight sub-basin areas. Based on, results from this study it is evident that grain size information is needed for better snow water equivalent determination using microwave radiometric techniques.

Estimation of Probable Effects of Grobal Warming on Water Resources in Japan Based on Long-term Meteorological Data Analysis

To estimate probable effects of grobal warming on water resources in Japan, long-term monthly data of temperature, precipitation and depth of snow cover are collected and analysed. Characteristics of precipitation in the period from May to September in defferent regions are compared over the cold decate and the warm decade. The relation between tempreture and yearly maximum depth of snow cover in the snowy regions is also investigated. The results show that drought in summer might become severe and snowmelt water might decrease with grobal warming.