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The impact of snow cover on seasonal ground frost and freeze-thaw processes is not yet fully understood. The authors therefore examined how snow cover affects seasonal ground frost in a coastal setting in northern Sweden. Air and soil temperatures were recorded in a paired-plot experiment, both with and without snow cover, during the frost season 2012–2013. The frequency, duration, and intensity of the freeze-thaw cycles during the frost season were calculated. The results showed that the freeze-thaw frequency was 57% higher at the soil surface and the intensity 10 °C colder in the spring of 2013, when the ground lacked snow cover. Furthermore, the duration of the seasonal freeze-thaw cycle was 30 days longer on average in cases where there was natural snow accumulation. The correlation between air and ground surface temperatures weakened with increased snow-cover depth. The authors conclude that continued increases in air temperature and decreases in snow in coastal northern Sweden might alter fr...

One of the most important factors affecting pavement performance is climate, including frost action and precipitation. The performance of pavements in frost-affected regions depends to a large degree on the depth of frost penetration. In this paper, a simple predictive tool is developed to calculate a new correction coefficient depending upon the thermal ratio and fusion parameter. The new correction coefficient can be used in follow-up calculations to estimate the depth of frost penetration for both uniform and layered soils in frost-affected regions to evaluate the performance of pavement. The results of the proposed method are found to be in excellent agreement with reported data in the literature with average absolute deviation being less than 0.8%. The predictive tool is simple, straightforward and can be readily implemented in any standard spreadsheet programme leading to accurate, smooth and non-oscillatory data points. The prime application of the method is as a quick-and-easy evaluation tool in c...

Through changing soil thermal regimes, soil moisture and affecting weathering and erosion processes plants can have an important effect on the physical properties and structure of soils. Such physi...

Frost heave, frost and snow depths on two earth hummocks (pounus) were monitored from 1992 to 2002 in Finnish Lapland. Frost heave was measured with motometers, frost depth with Gandahl's frost tube containing methylene blue, and snow depth with frost tubes above the ground surface. The annual range of frost heave was from 1 mm to 94 mm. The mean annual frost heave on a peat pounu was up to twice that on a mineral-cored pounu. Frost heave values on the pounus did not differ much from those from the surrounding mire. During the early summer, slow thawing of frost keeps the surface of pounus higher than the surrounding mire surface and this supports the formation of earth hummocks.

Freezing processes were monitored at five sites within the Wolf Creek basin, Yukon, Canada during the winter of 1998–1999. Ground temperatures were measured using thermocouples in hillslopes that had frost status ranging from permanent to seasonal. The timing of freezing and ground thermal regimes varied among the five sites and was controlled by (1) the variation in surface soil temperature, (2) frost status (seasonal vs. permanent), (3) moisture content of the active layer, (4) properties of the soil profile, and (5) the presence/absence of subsurface drainage. On slopes with permafrost, cooling was rapid and two-sided freezing closed the active layer several months after the onset of freezing. On a slope with seasonal frost only, dry soil conditions allowed frost to penetrate to depth. In contrast, a slope with seasonal frost that had continuous drainage, frost depths were shallow due to heat advected from flowing water. A simple one-dimensional conduction model with latent heat was used to si...

In this study, the snow and soil frost conditions in three different forest stand treatments in northern Sweden were investigated during winter and spring 1998/99. In total, 49 frost tubes and 25 snow gauges were used in one clear‐cut area, one multilayered shelterwood of mixed Scots pine (Pinus sylvesths) and Norway spruce (Picea abies), and one single‐layered shelterwood of old Scots pine. The snow cover was thicker and smoother and less soil frost was observed in the clear‐cut area than in the shelterwoods. In the multilayered shelterwood the mean snow cover was shallower than in the single‐layered shelterwood, but with larger spatial variation in snow depth related to the canopy density and with patches of snow and soil frost that lasted until early summer. Close to the shelter trees in the single‐layered shelterwood the deepest soil frost was observed during the winter and early start of snow melting and soil frost thawing in spring. In conclusion, the snow and soil frost depths in the shelterwoods w...

Harvesting of flax and hemp fibres in normal time in autumn often meets with special problems in the Nordic circumstances. These are mainly due to the short growing period and the cold and rainy period in autumn. The risk of formation of mold spores inside the harvested fibre plant bales is obvious (1). Even though the bales are dried in bale driers there is enough time for the molds to destroy the quality of the raw material. This is caused by both the slow drying process and the high microbiological activity of the moist material (3). This is the reason why the new Dry-line-method (2) is under research. Briefly the dry-line-method means: The frost affects fibre plants in Northern circumstances. In springtime the temperature is changing daily above and below the zero. This leads to the enlarging movement which is resulted from the frozen water and which is varying in different plant cell structures. When this takes place repeatly several times the movement also loose the bast fibre from the stem...

The rates of many processes that control rock breakdown into transportable particles are dependent upon rock temperature. In particular, frost-cracking depends largely upon the time spent within a range of subzero temperatures I call the frost cracking window. I present simple analytic solutions, detailed time series of thermal data from a field site, and a numerical model of subsurface temperatures that constrain the expected depth dependence of frost cracking. Analytic solutions using sinusoidal surface temperature histories result in predicted vertical profiles of frost-cracking intensity that depend upon the location of the frost-cracking window within the range of surface temperatures. In some cases, the expected frost cracking intensity decreases monotonically with depth, while in others it displays a distinct maximum at depth. I use hourly temperatures measured over the 1-yr interval April 1995 through March 1996, at 8 depths up to 42 cm into a granitic bedrock surface in the Laramie Range, Wyoming, to constrain an in situ thermal diffusivity of 1.7 mm2 s-1. These temperature histories suggest that frost cracking at this site should decrease monotonically with depth into the rock. I also use this time series of temperatures to calibrate a numerical thermal model in which the top boundary condition is set by a surface radiation balance. The data require both a low albedo of the rock surface (0.1), and a high atmospheric transmissivity (0.9). I then explore the expected near-surface temperatures at other sites by running the model with different annual mean temperatures, latitudes, and slopes. The resulting simulations suggest that at lower mean annual temperatures, as are found in higher latitude and altitude sites, the frost cracking maximum should both amplify and deepen into the subsurface.

A review of frost conditions under a series of plant associations, which ranges from open-water swamp to dense forest on hummocks presumably generated by frost heaving in the past, reveals a continuous subsurface frost series. The frost series ranges from permafrost without active layer beneath open swamp-water to a total lack of permafrost beneath dense conifer-birch forests. The runoff in both extreme environments consists of melted winter precipitation; this is augmented by an active layer of water in the intermediate types of the environment. — M.E. Burgunker