Search

Snowpack produces a thermal layer that protects soil from freezing and provides a pulse of nutrient-rich water in spring. Climate forecasts for Maine indicate 20–60% reduction in snowfall by 2050. In January 2015, we initiated a snow-removal experiment in Old Town, ME to investigate the impact of snow loss on forest soil conditions. Snow removal significantly lowered winter organic horizon temperatures by 2 °C on average. Soils in snow-removal plots were 25% wetter during the vernal transition because precipitation was not intercepted by snow. These rain-on-soil events caused the formation of concrete frost, delaying soil thaw in snow-removal plots. Our results provide evidence that snowpack loss increases soil frost and can also increase soil moisture, potentially altering biotic function within a coniferous forest type.

Soil frost can have a substantial impact on water flows at the soil surface and—potentially—alter the dynamics of catchment runoff. While these findings are mainly based on studies from alpine and Northern-latitude areas (including permafrost areas), little is known about the significance of soil frost for hydrology in pre-alpine areas, i.e. the region at the transition from central European lowlands to high-alpine areas. Here I synthesize soil temperature data and soil frost observations from ten sites in Switzerland to assess the occurrence of soil frost and to determine its impact on catchment runoff. In addition, a well-established numerical model was used to reconstruct the presence of soil frost in two first-order catchments for single runoff events and winters. The data clearly demonstrates that shallow soil frost has formed regularly in this altitudinal range over the past decade. The presence of a frozen soil surface was found to be highly variable among the sites under study and did not significantly correlate with altitude or forest density. For the first-order catchments, it was not possible to relate important flood peaks or increased runoff coefficients to winter situations with substantial soil frost. Thus, the present analysis suggests that although soil frost is widespread and regularly occurring at this altitudinal range, it has no significant impact on winter runoff in pre-alpine watersheds.

Embankment deformation is a key consideration in high speed railway construction. Frost heave due to temperature and moisture variation is critical to consider in areas of seasonally frozen ground. This paper examined ground temperatures, frost heave, and moisture content in 2013–2014 at two sites along the embankment of the Harbin-Dalian Passenger Dedicated Line (HDPDL) railway. The railway is in seasonally-frozen ground of Jilin Province, China. The embankment at one site (K977) was built on the undisturbed ground surface while the other was in a cut section (K1004). Displacement measurements over one year indicated that frost heave of 14 mm at K977 and 25 mm at K1004 occurred in ballast during the freezing season. During the annual freeze-thaw period, soil moisture content varied drastically in the upper 0.6 m. The frost depth and freezing index were strongly and positively correlated during the freezing season. Soil moisture content was regarded as the primary control on the amount of frost heave, while frost depth was secondary. Furthermore, water vapor diffusion may have been an important contributor to the formation of near-surface ice. At K1004 site, the maximum recorded deformation was large and exceeded the 15 mm Chinese standard for maximum allowable heave. This suggested that high ground water level increased the amount of frost heave.

1 Standing corn residue has been proven to reduce wind erosion in Northeast China, but how standing corn residue affects soils during winter remained unclear. Our objective was to compare soil frost depth associated with two zero-tillage methods [i.e., chopping corn stalks into small sections then spread them on soil (hereafter referred to as ‘CCR’) and standing corn residue (hereafter referred to as ‘SCR’)]. Frost tubes were used to determine soil frost depth, and soil heat flux plates were used to measure soil heat flux 8-cm beneath the soil surface. Compared with CCR treatment, SCR reduced maximum soil frost depth significantly ( p

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...

The NICE model was extended to include the effect of the micro-topography in slope and shading characteristics and the phase changes in soil moisture on snow/frost depths and snowmelt runoff by combining the land-surface, the multi-layer runoff, and the groundwater flow models (NICE-SNOW). The model was applied to the upstream regions of shrinking Kushiro Mire in the invasion of alder, where the spring runoff affects greatly the annual sediment and nutrient transports because the spring flood continues in longer time than that in typhoon seasons. The simulation reproduced excellently the observed values of annual river discharge including snowmelt runoff with the greater time-to-peak of runoff than in snow-free period, in addition to snow depth, frost depth, soil temperature, soil moisture, and groundwater level, by conducting the quantitative assessment of goodness-of-fit and parameter sensitivity analysis. We quantified that the mechanism of spring snowmelt runoff is related to changes in micro-topography, soil structure, soil temperature, soil moisture, and groundwater flow. The model shows that the local effect of snow depth and the frost depth disappears in the snowmelt runoff discharge of catchment in the same way as some previous researches though they are very important as water resources of catchment. After the frozen soil restricts the infiltration in the coldest part of winter, the thawed soil increases the pore size in the early spring. The NICE-SNOW could explain the snowmelt flood continues a longer time than that in the typhoon period because some part of meltwater flows as an intermediate flow in the partially-thawed hillslope soil layer. This is also related to the simulation result that more than half of total soil moisture stays unfrozen at some places even in winter periods, which indicates that there is a high degree of spatial heterogeneity of frozen ground.

The frost table depth is a critical state variable for hydrological modelling in cold regions as frozen ground controls runoff generation, subsurface water storage and the permafrost regime. Calculation of the frost table depth is typically performed using a modified version of the Stefan equation, which is driven with the ground surface temperature. Ground surface temperatures have usually been estimated as linear functions of air temperature, referred to as ‘n-factors’ in permafrost studies. However, these linear functions perform poorly early in the thaw season and vary widely with slope, aspect and vegetation cover, requiring site-specific calibration. In order to improve estimation of the ground surface temperature and avoid site-specific calibration, an empirical radiative–conductive–convective (RCC) approach is proposed that uses air temperature, net radiation and antecedent frost table position as driving variables. The RCC algorithm was developed from forested and open sites on the eastern slope of the Coastal Mountains in southern Yukon, Canada, and tested at a high-altitude site in the Canadian Rockies, and a peatland in the southern Northwest Territories. The RCC approach performed well in a variety of land types without any local calibration and particularly improved estimation of ground temperature compared with linear functions during the first month of the thaw season, with mean absolute errors

a b s t r a c t Soil frost depth in forest ecosystems can be variable and depends largely on early winter air temperatures and the amount and timing of snowfall. A thorough evaluation of ecological responses to seasonally frozen ground is hampered by our inability to adequately characterize the frequency, depth, duration and intensity of soil frost events. We evaluated the use of ground penetrating radar to nondestructively delineate soil frost under field conditions in three forest ecosystems. Soil frost depth was monitored periodically using a 900 MHz antenna in South Burlington, Vermont (SB), Sleepers River Watershed, North Danville, Vermont (SR) and Hubbard Brook Experimental Forest, New Hampshire (HBEF) during winter 2011-2012 on plots with snow and cleared of snow. GPR-based estimates were compared to data from thermistors and frost tubes, which estimate soil frost depth with a color indicating solution. In the absence of snow, frost was initially detected at a depth of 8-10 cm. Dry snow up to 35 cm deep, enhanced near-surface frost detection, raising the minimum frost detection depth to 4-5 cm. The most favorable surface conditions for GPR detection were bare soil or shallow dry snow where frost had penetrated to the minimum detectable depth. Unfavorable conditions included: standing water on frozen soil, wet snow, thawed surface soils and deep snow pack. Both SB and SR were suitable for frost detection most of the winter, while HBEF was not. Tree roots were detected as point reflections and were readily discriminated from continuous frost reflections. The bias of GPR frost depth measurements relative to thermistors was site dependent averaging 0.1 cm at SB and 1.1 cm at SR, and was not significantly different than zero. When separated by snow manipulation treatment at SR, overestimation of soil frost depth (5.5 cm) occurred on plots cleared of snow and underestimation (−1.5 cm) occurred on plots with snow. Despite some limitations posed by site and surface suitability, GPR could be useful for adding a spatial component to pre-installed soil frost monitoring networks. Published by Elsevier B.V.

Automated monitoring that combines time-lapse photography and sensor-based data logging can elucidate the environmental conditions, processes and rates of soil movement on remote periglacial hillslopes. This study presents the results from 5 years of time-lapse photography of soil movements, supported by time series data on frost heave, soil temperature, soil moisture and surface weather, on an alpine stone-banked lobe subject to frequent diurnal freeze-thaw cycles and deep seasonal frost on Mt Ainodake in the Japanese Alps. The lobe is dominated by biannual shallow soil movements, mostly originating from diurnal frost heave by needle ice or shallow ice lens formation and approximated by potential frost creep. The surface velocity shows a small interannual variation mainly reflecting snow conditions that control the spatio-temporal variability of freeze-thaw action, while it is independent of mean annual air temperature that influences the intensity of seasonal freezing. Occasional rill erosion occurs when the topmost frozen soil is rapidly thawed and super-saturated by intensive rainfall during seasonal thawing periods. Copyright © 2014 John Wiley & Sons, Ltd.

The Korean Peninsula is considered as a seasonal frozen area that is thawed in the spring and frozen in the winter. The influence of fines of the frost susceptibility of subgrade soils were established by laboratory freezing tests simulating closely the thermal conditions in the field. During the winter season, the climate is heavily influenced by the cold and dry continental high pressure. Because of siberian air mass, the temperature of January is on average. This chilly weather generate the frost heaving by freezing the moisture of soil and damage potential of the geotechnical structure. In the freezing soil, the ice lenses increase the freeze portion of soil by absorbing the ground water with capillary action. However, the capillary characteristics differ from the sort of soil on the state of freezing condition. In this study, ten soil samples are prepared. The basic physical property tests were performed by following the Korean Industrial Standard and the soil specimens were classified by the Unified Soil Classification System (USCS). These classified soils are used to perform the laboratory opened systems freezing test in order to determine the frost heaving characteristics of soils such as unfrozen water content, heaving amount, and freezing depth.

Frost heave, which is the volumetric expansion of frozen soil, has great ecological significance, since it creates water storage spaces in soils at the beginning of the growing season in cold temperate forests. To understand the characteristics of frost heave in seasonally frozen soil and the factors that impact its extent, we investigated the frost heave rates of forest soil from different depths and with different soil moisture contents, using both lab-based simulation and in situ measurementin a broadleaved Korean pine forest in the Changbai Mountains (northeastern China). We found that frost heave was mainly affected by soil moisture content, soil type, and gravitational pressure. Frost heave rate increased linearly with soil moisture content, andfor each 100% increase in soil moisture content, the frost heave rate increased by 41.6% (loam, upper layer), 17.2% (albic soil, middle layer), and 4.6% (loess, lower layer). Under the same soil moisture content,the frost heave rate of loam was highest, whereas that of loess was lowest, and the frost heave of the uppermost 15 cm, which is the biologicallyenrichedlayer, accounted for ~55% of the frost heave. As a result, we determined the empirical relationship between frost heave and freezing depth, which is important for interpreting the effects of frost heave on increases in the storage space of forest soils and for calculating changes in soil porosity.

The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of −0.18 ± 0.03 cm yr−1, resulting in a net decrease of 8.05 ± 1.5 cm over 1967–2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr−1 in most parts of China during 1950–2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze–thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.

Frost tubes filled with methylene blue solution are commonly used tools for measuring soil frost and thaw depths in the field. To quantify the accuracy of this method, soil frost depths were measured in agricultural fields in the Tokachi district of the northernmost of Japan's main islands. The frost depths measured using frost tubes coincided with those determined from direct observations of the soil profile. The root mean square error (RMSE) between these two methods (i.e. frost tubes and direct observations) was ± 0.035 m, which is expected for frost tubes in this region. The soil temperature profile was characterized over four winters using thermocouples to estimate soil frost depths in an experimental field in central Tokachi. Frost depths were also measured using frost tubes during this period. A scatter diagram of the frost depths obtained using these two methods showed a concentration of points along a 1:1 line. The RMSE between these two methods was ± 0.028 m, suggesting that frost depth can be accurately estimated from the soil temperature profile. Unlike soil frost depth, soil thaw depths measured using frost tubes were consistently deeper than those determined through direct observation of the profile of soil hardness. This might be true because the frozen soil around the frost tube thawed earlier because of the greater insolation and heat conduction from atmosphere resulting from the decrease in snow cover as a result of snowmelt around the frost tube. However, because a scatter diagram of the thaw depths obtained using these two methods showed an approximately linear relation, the thaw depths measured using frost tubes can be calibrated using this relation.

In the northernmost region of Japan (Hokkaido Island), earlier onsets of thick snowcover in recent years (post 1980) have reduced the penetration depth of soil frost, resulting in over-winter survival of unharvested small potato (Solanum tuberosum) tubers that emerge as weeds in the spring in rotation crop fields. To prevent the occurrence of potato weeds, a method was developed to manipulate soil-frost depths by artificially controlling snowcover thickness, guided by a simple numerical model that simulates soil freezing-thawing processes using daily mean air temperature and snowcover thinckness as input variables. The method involves removal of snowcover to expose the soil surface in the beginning of winter until the soil freezes to a sufficient depth. After that time, snow is deposited back or allowed to accumulate naturally to prevent further penetration of frost, which may cause undesirable delay in the seeding of spring crops. Field trials indicated that the model predicted frost depths within several centimeters of observed values, when measured temperature and snowcover thickness were used as model input. Based on the field and laboratory data, a soil temperature of −3°C is necessary for complete elimination of potato tubers. To achieve this temperature in potato-burial zones without causing excessive freezing, an optimal frost depth is 0.3 to 0.4 m. The method is being adopted by progressive potato producers in the region, who use tractor-mounted snow ploughs to manipulate snowcover over a large scale. This is an emerging new technology for agricultural adaptation to climate variability.

The dynamics of stone-banked lobes were investigated by monitoring soil movements and environmental parameters over 14 years on a limestone slope subject to deep seasonal frost. The monitored parameters included downslope soil movement, frost heave, soil temperature, moisture and snow depth. Despite being composed of the same soil, lobes on the upper slope (∼20°) display pressure ridges on the tread and terminate in a high riser (∼1 m), whereas lobes on the lower slope (∼10°) have a flat tread and a low riser (∼0.5 m). The long-term monitoring demonstrates that gelifluction, resulting from seasonal frost heave of approximately 5 cm and thaw settlement, occurs annually in the lower lobes at a mean surface rate of 4 cm a−1 and with a movement base at approximately 40-cm depth. The rate of gelifluction shows some interannual fluctuation depending primarily on the annual frost heave amount, but overall regularity of the rate and depth of movement regardless of seasonal frost depth results in lobes having similar morphologies. On the upper, steeper lobes located just below late-lying snow patches, rapid, shallow mudflows (∼20 cm thick) are often superimposed on gelifluction. The rate of surface movement varies spatially, in places exceeding 2 m per event. The prolonged water supply and low consistency limits of the limestone soil favour mudflows on seasonal thawing. The transported sediments pile up near the lobe front, resulting in a high riser. Such modification of solifluction lobes by mudflows can occur in other slopes with similar gradients, soils, frost and snow conditions. Copyright © 2010 John Wiley & Sons, Ltd.

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...

Rates and processes of frost weathering in the Alps were investigated by visual observations of intensively shattered rocks, continuous monitoring of frost wedging and rock temperatures in bedrock and measurements of rockfall activity. Rapid frost weathering of hard-intact rocks occurs along lakes and streams where seasonal freezing promotes ice segregation in the rock. Otherwise, rocks require pre-existing weakness or a long exposure period for intensively shattered. Automated monitoring shows that crack opening occurs at three scales, including small opening accompanying short-term frost cycles, slightly larger movements during seasonal freezing and occasional large opening originating from refreezing of snow-melt water during seasonal thawing. The opening events require at least partial water saturation in the crack. The repetition of crack opening (frost wedging) results in permanent opening and finally debris dislocation. Debris collections below fractured rockwalls show that pebble falls occur at an average rate of about 0.1 mm a − 1 with significant spatial and inter-annual variations. Occasional large boulder falls significantly raise the rockwall erosion rates, controlled by such factors as the joint distribution in the bedrock, repetition of annual freeze–thaw cycles and extraordinary summer thaw.

The depth of soil frost is decreasing in cold regions around the world as a result of climate warming. To evaluate the potential impacts of the reduction in frost depth on the hydrologic cycle, it is necessary to understand snowmelt infiltration processes in frozen soils. A field study was conducted at an agricultural site characterized by volcanic ash soil in Tokachi, Hokkaido, Japan, where frost depths have decreased significantly in the last 20 yr. Soil temperature, water content, matric potential, snow cover, and meteorological parameters were monitored to quantify snowmelt infiltration flux for four winters that had different snow and soil conditions. When snowmelt began, the soil frost was 0.1 to 0.2 m thick in two winters and was absent in two other winters, providing a unique opportunity to compare snowmelt infiltration under frozen and unfrozen conditions. Most of the snowmelt water infiltrated into the soil under both frozen and unfrozen conditions, indicating that the frozen soil layer did not impede infiltration. The lack of flow impedance in the frozen soil was partly due to relatively high air temperature and an absence of freeze-back events during the snowmelt period. Furthermore, the temperature of the frozen soil layer was close to 0°C when the melt started, meaning that very little meltwater refroze in the soil before the temperature reached 0°C. The thick (>1 m) snow cover insulated the soil surface, allowing the frozen soil layer to warm up with the upward conduction of heat from the unfrozen layer below. These results indicate the importance of the interaction between snow cover and soil, which can be significantly affected by climate change.

Hillslope runoff in permafrost regions covered by organic soil is strongly influenced by subsurface flow in the active layer, as well as surface flow where the active layer is very shallow. Flow rates in the organic-rich active layer are strongly dependent on the depth to the thawing front (i.e. frost table) and the corresponding soil hydraulic conductivity at that depth. Therefore, hydrological models for permafrost terrains need to simulate the thawing of the active layer accurately. In order to simulate the downward movement of the frost table, a simple heat-conduction model was proposed and compared to field data from a wet, organic-covered watershed in a discontinuous permafrost region of Canada. Ground heat flux was measured simultaneously using the calorimetric, gradient, and flux-plate methods to increase the confidence in data sets. The majority (>86%) of ground heat flux was used to melt the ice in frozen soil, and the soil temperature had a linear profile from the ground surface to the frost table when averaged over several days. Assuming a linear temperature profile, the proposed method calculates the daily rate of thawing from ground surface temperature and bulk thermal conductivity, where the latter is essentially determined by soil water content. Simulated depths to the frost table during three thaw seasons (2003-2005) matched closely with the observed data for two contrasting ground-cover types with distinctly different thaw rates. The method can be easily implemented in hydrological models, and will provide a useful tool for simulating hillslope drainage in organic-covered permafrost terrains, and for evaluating the effects of topography and land cover on the temporal and seasonal variability of the frost table.

Our aim is to measure and explain the seasonal changes in soil ice content in the frost boils of Galbraith Lake, Alaska. Instruments were installed in a frost boil to monitor the ground surface position and soil state over a period of 4 years. By comparing the subsidence and thaw rates, we calculate the soil ice content as a function of depth. Measured soil temperatures, liquid water contents and bulk apparent thermal conductivities are used to estimate latent heat production and release in the soil. The frost boil heaves during freezing and settles during thaw while the surrounding tundra heaves negligibly, but subsides measurably. Despite large changes in freezing rates from year to year, total heave and its distribution across the frost boil are similar between years. Winter air temperature and snow depth influence the freezing rate and ice distribution as a function of depth, but not the overall heave. This suggests that heave is controlled by water availability rather than the rate of heat removal from the soil. Areal ground subsidence rates between 2 and 5 cm/yr are due to the disappearance of ice at the base of the active layer, raising the possibility of ongoing thermokarst expansion around Galbraith Lake.

The occurrence of snow and soil frost influences hydrology and, in turn, the mechanisms of soil erosion processes in cold regions. For these regions, reliably modeling the dynamics of snow accumulation and melt, and soil frost formation and melt, is necessary prior to accurately predicting runoff and erosion. Only then will methods for predicting the rates and amounts of soil erosion by water be established on a firm hydrological footing. This article examines the potential of an energy budget approach to simulate the magnitude and variations of snow and soil frost depths. It is assumed that the net sum of all energy components in the environment is consumed or compensated by water phase change occurring near or under the ground surface, such as snow melting or soil freezing and thawing. Testing indicates that this energy budget approach demonstrates promise to simulate winter hydrology and to be adapted to erosion prediction models.

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...

Frost boils in northern Alaska vary from large, 2–3-m diameter, barren non-sorted circles to completely vegetated hummocks. Summer warmth increases southwards from the coast. Average thaw-layer thickness shows the opposite trend. Frost heave shows no trend along the climate gradient but is affected by soil texture. Heave is greatest on frost boils with fine-grained sediments. Biomass increases from 183 g m � 2 at the coast to 813 g m � 2 in the Arctic Foothills. An aggrading permafrost table is evident in most of the frost-boil soil profiles, indicating that, over time, accumulation of plant biomass leads to reduced thaw-layer thickness. A conceptual model suggests how vegetation affects the morphology of patterned ground forms. In the coldest parts of the High Arctic well-developed frost boils do not form and there is little vegetation on frost boils or the inter-boil areas. In the warmest parts of the Low Arctic, vegetation is usually sufficient to stabilize the frost boil soils. Frost boils play an important role in Arctic ecosystems functions, including the flux of trace gases to the atmosphere, flux of water and nutrients to streams, and the recycling of important nutrients to wildlife populations. Copyright # 2004 John Wiley & Sons, Ltd.

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...

The effect of soil frost on runoff was investigated using a comprehensive data set collected at the Svartberget Experimental Forest, near Vindeln, Vasterbotten in northern Sweden. Measurements of snow depth, soil temperature, frost depth and other climate parameters have been made at three sites since 1981, as part of a long-term climate monitoring programme. Simulation residuals from the HBV rainfall-runoff model, in which no effect of soil frost is assumed, were compared with 16 years of measured soil frost conditions. A simple model for simulation of soil frost depth was developed and incorporated into the HBV model. The model parameters were calibrated to observations of snow depth, soil frost depth, groundwater levels and runoff, by use of a simple weighted optimization criterion. No clear effect of soil frost could be seen on the timing and magnitude of runoff in this analysis, or when analysing data on the conservative oxygen isotope O-18. The soil at the forested site froze in only slightly more than half the years, despite the high latitude and low winter temperatures. Furthermore, the soil had often thawed before the start of the spring flood. Almost all spring floods, therefore, occurred when the soil was unfrozen. Snow depth and soil frost depths were inversely related, with the deepest soil frost during winters with little snow. Soil frost therefore is unlikely to aggravate the very high floods in forested basins of this type, except perhaps under exceptional circumstances such as large rain events on frozen ground. Copyright (C) 2002 John Wiley Sons, Ltd.

An existing, physically based soil freezing model applicable to humid climates is modified for use in the central and western United States. Simulations using the state-of-the-art Simultaneous Heat and Water (SHAW) model indicated that the original model required the addition of a water budgeting scheme and alteration of the equation for soil thermal conductivity. Using only daily temperature, liquid precipitation, snowfall, and snow cover, this new model allows the simulation of maximum seasonal frost depths at several thousand U.S. stations. Comparison of the model-derived maximum frost depths with observed and soil temperature–inferred soil freezing maxima at 32 arid and semiarid locations indicates excellent agreement. Observed maximum soil freezing depths, ranging from 0 to over 100 cm, are simulated, with an average absolute error of 5.4 cm. At individual stations, the seasonal penetration and thawing of soil freezing tracks that of the observations very closely, regardless of ambient soil ...

The present paper describes a model for frost assessment in mountainous areas in relation to forest management. Data were collected at 38 locations within a 625 km 2 region, which is characterised by a diverse topography and vegetation cover. Air temperature measurements were performed during the peak of the growing season. (July–August 1996) in the southern Swedish mountains at elevations between 500 and 1200 m a.s.l. The variation in nighttime minimum temperatures was analysed in relation to the prevailing weather and terrain type of the measuring sites. From the analysis of the temperature and weather conditions, i.e., wind and radiation, it was concluded that more than 90% of the frost situations, occurring during the study period, were of the radiation type. It was further concluded that the variation among the studied stations was closely related to the terrain type during these situations. Frost occurred most frequently in narrow valleys, then in concave and flat locations. Elevated and convex areas were found to have very few situations of radiation frost. Local terrain information was used together with a calculated frost index for assessment of the spatial variation in frost risk. Furthermore, a grid net was applied to the study area and the pixels were given a terrain form of the type convex, slope, flat, wide concave or narrow concave according to the dominating terrain curvature. For each pixel a frost index value was estimated from the recorded temperatures at the field stations. A cluster analysis was used to group the terrain types according to the index, whereby six obvious clusters were obtained each with clearly differentiated frost intensity. The analysis showed that this kind of treatment is a suitable method for assessing the spatial variation in frost risk.

Ground water and surface water interaction in the prairie pothole region of the United States and Canada is seasonally dominated by the presence of thick, frozen soil layers that affect infiltration. During a spring thaw, the subsoil may remain frozen, preventing infiltration. The impact of the frozen soil layer on the timing of infiltration of depressional-focused recharge to the ground water is not clearly understood. The objective of this paper is to relate changes in the water table during spring to changes in frost depth and soil water content. A depression and adjacent upland study site were instrumented with CRREL-type frost tubes, neutron probe access tubes, and ground water monitoring wells. Increases in water table levels in a depression occurred before the frost layer decomposed and infiltrating water quickly formed a recharge mound. Water table responses at the upland site took place as two events. The first event was a gradual rise, probably caused by the lateral dissemination of the recharge mound. The second rise was a rapid rise coinciding with the decomposition of the soil frost layer. Because of the accumulation of surface water in depressions, agricultural practices that remove water from a field can affect water resources management by limiting the addition of water recharge to unconfmed ground water.

A mathematical model of snow-cover influence on soil freezing, taking into account the phase transition layer, water migration in soil, frost heave and ice-layer formation, has been developed. The modeled results are in good agreement with data observed in natural conditions. The influence of a possible delay between the time of negative temperature establishment in the air and the beginning of snow accumulation, and possible variations of the thermophysical properties of snow cover in the wide range previously reported were investigated by numerical experiments. It was found that the delay could change the frozen-soil depth up to 2–3 times, while different thermophysical characteristics of snow changed the resulting freezing depth 4–5 times.

The prairie pothole is an important hydrologic component of the Prairie Pothole Region of North America. Snow cover and frozen soil affect runoff and soil water recharge, but little is known about their temporal and spatial characteristics across a prairie pothole. A 2-ha prairie pothole near Morris, MN was instrumented to assess snow cover, soil water, and frost depth at 11 locations across two that traversed the major and minor axes. Measurements were made over three winters beginning in 1990. Snow cover was on the side of a ridge located on the NW end of the major axis and shallowest least variable in the bottom of the depression. Maximum of of the freezing front in the soil approached 25 mm d -1 whereas maximum depth of soil freezing neared 1.2 m across the site during this study. Rate of soil freezing during the fall was more at positions of higher elevation and with snow cover. and snow cover accounted for as much as of the variability rate of soil freezing across the site. Snow cover accounted for as much as 46% of the variation in maximum frost penetration; penetration was deepest at positions with the least snow cover. Thawing of the soil profile was most rapid in the bottom of the depression and appeared to be accentuated by infiltration of surface water through localized unfrozen soil pores or cracks. Maximum surface thaw rate approached 40 mm d -1 . Soil water recharge occurred during spring snowmelt, but snow cover accounted for

裸地・積雪地・植生地における凍土の凍結深について,鉛直1次元モデルに中国東北部の季節凍土帯の気象データを用いて,気象条件・地表面パラメータに対する依存性を調べた.その結果,裸地については気温が凍結深を支配すること,風速が大きくなると凍結深がやや減ることが確かめられた.また,土壌の含水率への依存性は含水率が0.1以下の場合を除くと小さいこと,乾燥密度にも大きく依存しないことがわかった.積雪が存在する場合には,凍結深が積雪深のほかに雪の熱物理係数にも強く影響されることがわかった.植生地については,森林を想定すると森林密度の凍結深への影響は大きくないことが示された.続いて,積雪下の凍結深の推定について,数値計算によらない方法を提案した.この方法は積雪内の温度分布を半理論的に解いて求めたものであり,汎用性をもっている.しかしながら,推定に必要な項目が多いなどの問題点も抱えている.

Soil temperatures play a key role on the dynamics of geomorphological processes in periglacial environments. However, little is known about soil thermal dynamics in periglacial environments of semiarid mid-latitude mountains, where seasonal frost is dominant. From September 2006 to August 2012 we have monitored soil temperatures at different depths (2, 10, 20, 50 and 100 cm) in a solifluction landform located at 3005 m.a.s.l. in the summit area of the Sierra Nevada (South Spain). Mean annual temperatures in the first meter of the soil ranged from 3.6 to 3.9 °C while the mean annual air temperature at the nearby Veleta peak was 0.08 °C. Therefore, these data point out the inexistence of widespread permafrost conditions today in this massif. Seasonal frost controls the geomorphodynamics even in the highest lands. Climate conditions have shown a large interannual variability, as it is characteristic in a high mountainous Mediterranean environment. These variations are reflected in the patterns of soil thermal dynamics. The depth and duration of the frozen layer are strongly conditioned by the thickness of the snow cover. The date of the first significant snowfalls conditioned the beginning and rhythm of freezing of the soil. Wet years resulted in a thick snow cover which insulated the ground from external climate oscillations and favored a shallow frost layer (2008–2009, 2009–2010 and 2010–2011). On the other hand, years with low precipitations promoted deeper freezing of the soil down to 60–70 cm extending until late May or early June (2006–2007, 2007–2008 and 2011–2012). When snow melted a high increase of temperatures of 10–12 °C in few weeks was recorded at all depths. At this time of the year, periglacial activity is enhanced due to higher water availability and the existence of freeze–thaw cycles. These were recorded mostly in spring and autumn in the first 50 cm depth of the soil, ranging from 9.8 days (at 2 cm) to 3.7 days (at 50 cm). However, the inactivity of solifluction landforms suggests that the combination of present-day soil temperatures together with moisture conditions is not favorable to promote solifluction activity in the periglacial belt of the Sierra Nevada. Future climate scenarios point to a temperature increase and precipitation decrease in the area, which would entail deeper but shorter frozen soil layers. These conditions would not be favorable for active periglacial slope processes in the Sierra Nevada.

Evaluation of WEPP (Water Erosion Prediction Project) of USDA-ARS indicates the winter subroutines in this model predict longer soil freezing periods and deeper frost depths than are actually observed in many areas. An energy budget approach was selected and tested for its potential in replacing the current winter subroutines in WEPP. This approach has been used to model snow pack development and snow melting in many studies. It has also been used to predict the occurrence of soil freezing. This project further develops the energy concept to quantify temporal depth variation of soil frost. It is based on an energy balance relationship composed of four components: net radiation, latent heat, sensible heat and the heat flow through the soil surface. Results of testing with observed data show this approach satisfies our needs and has flexibility for future enhancements.

Seasonal soil freezing is an important natural perturbation common in cold regions around the world. A thorough evaluation of ecological responses to seasonally frozen ground is hampered by our inability to adequately characterize the frequency, depth, duration and intensity of soil frost events. When soil freezes, its dielectric value drops creating a detectable interface. Ground penetrating radar (GPR) has the potential to nondestructively quantify seasonal soil freezing in forests, though it requires further evaluation before it can be used in ecological applications. A series of test plots were established at sites in Vermont (2) and New Hampshire (1). Each site was fitted with frost tubes (30) to make direct comparisons with GPR estimates of frost depth using a SIR-3000 GPR system equipped with a 900 MHz antenna (Geophysical Survey Systems, Salem, NH) during winter 2011-2012. Half of the experimental plots were shoveled free of snow every other week to increase frost penetration. GPR was able to reliably detect and delineate frost at depths greater than 10 cm. Favorable conditions for GPR include bare soil or shallow snow; while standing water, wet snow and surface thawing interfered with detection. Soil frost was detectable through snow 50cm. The best use of GPR would be intensive campaigns where capturing spatial variability is valuable.

A one-dimensional heat flow model is developed to estimate depths of soil freezing and thawing using a daily time step. This physically based model assumes near-saturated soil moisture conditions and simulates freezing under bare soil and sod using only those meteorological variables observed at cooperative network stations (i.e., daily temperature, precipitation, and snow depth). Therefore, using this relatively dense observation network, climatological model-derived frost depth statistics can be developed for stations in regions where soil conditions are typically near saturation during the winter. Soil-freezing estimates should be useful in a variety of applications, especially those concerned with agricultural and engineering design specifications. Based on comparisons with measured soil temperature data, the model successfully captures the seasonal progression, rate, and maximum depth of soil freezing and thawing at several climatically diverse locations. Verification results indicate that m...

In the winters of 2010 and 2011, several hundred kilometers of the Finnish railway network had decreased speed limits due to uneven rail caused by frost problems. To study the causes more closely, Tampere University of Technology has developed a monitoring system for measuring the frost depth and frost heave of railway track structures at selected sites across a range of different climatic zones in Finland. The system includes measuring the temperature using analog semiconductor-type temperature sensors placed on 100- to 500-mm intervals down to a depth of 3 m. Linear displacement transducers installed on both ends of instrumented sleepers are used for measuring frost heave and/or settlement of the sleepers. The moisture content in different layers is measured with dielectric-type moisture sensors. Two kinds of data loggers are used for data collection, with data being transferred from the field sites via a wireless network connection. The first monitoring sites have collected and sent data since 2008 with minimum maintenance. The final purpose of the monitoring is to enable modeling of frost heave in the field based on material properties determined in the laboratory and conditions (moisture, temperature) in the field.

Rock temperatures were monitored for a year at two alpine rockwalls in the Akaishi Range, Japan, where permafrost is absent. Diurnal frost and thaw penetration depths were evaluated from subsurface isotherms drawn on the basis of the temperature records at 0, 10 and 40 cm depths. The surface of the rockwalls experienced more than 100 diurnal freeze-thaw cycles, most of which accompanied a frost or thaw penetration shallower than 50 cm, and several long duration cycles with deeper frost or thaw penetration. Theoretical frost and thaw depths were also calculated by incorporating the surface freezing indices into the modified Berggren equation, the results from which were then compared with the actual values. The modified Berggren equation provided values that showed a strong correlation with observed depths, despite somewhat underestimating the actual values. Using the modified Berggren equation, the seasonal frost depth in the observed winter was estimated to be about 4·5 m. The frost and thaw depths are considered to give the maximum estimation of the depth to which frost-induced cracking can propagate in the bedrock.

In order to establish the amount of removal of SO2 and sulphates from the lowest layer of the atmosphere during frost formation, a field measurement experiment was conducted in January 1990 in the Ravenna area. Frost can bring about removal of particles, gases and hydrosoluble substances. In common with areas of the Po Valley, Ravenna is frequently subjected to atmospheric conditions that can cause frost. During the winter of 1990, clear skies at night, that were associated with high pressure fields, strongly influenced the formation of frost. Close to industrial plants, characterized by wet emission of plumes, this frost has an adverse impact on soil, commonly known as ‘chemical snow’. A large number of frost samples, collected in three locations representing typical but different features of the area (rural, urban and sea front sites), were analyzed. Analysis of the data reveals that SO2 is the major contributor SO4 −− trapped in frost.

[1] The retreat of the seasonal polar cap at the Phoenix landing site is analyzed through observations of high resolution images and thermal modeling of the CO2 frost mass. Numerical simulations indicate that the onset of CO2 frost formation occurs around Ls = 220° at 68°N; however, the polar hood prevented imaging of the surface during this time. In the late winter/early spring a continuous layer of frost coated the surface obscuring the underlying polygonal patterns; however, rocks are clearly evident indicating that the frost depth was relatively shallow. Rare dark fans originating from rocks are also observed in an image from early spring. Frost dissipated from the polygon centers first and lingered longer in polygon troughs. Polygon centers were first exposed on Ls = 13.9°, and the polygon troughs were frost free by Ls ∼57°. Frost distributions varied slightly between geologic units; however, in general, global observations at similar latitudes are consistent with what is seen in the Phoenix region. A series of hypotheses is also explored to explain the preference for the CO2 frost to linger in the troughs: lower thermal inertia material in the troughs, aeolian redistribution of frost, burial of the ice table via aeolian redistribution of dust, and shadowing. Each of these hypotheses has drawbacks to explaining this phenomenon as stand-alone components. Shadows do play a role in keeping the CO2 frost on the surface; however, this effect is small and cannot alone account for the observations.

[1] A dramatic reduction in soil frost depth has been reported for Hokkaido Island of northern Japan over the last 20 years. Since soil frost strongly affects snowmelt infiltration and runoff, the reduction in frost depth may have altered the water and nutrient cycles in this region. A paired-plot experiment was conducted in an agricultural field in Tokachi, Hokkaido, to compare the movement of soil water at different frost depths, controlled by manipulating the depth of snow cover. Snow was removed to enhance soil freezing in the treatment plot and was undisturbed in the control plot. The soil froze to a maximum depth of 0.43 m under the treatment plot and 0.11 m under the control plot. During the freezing period, the amount of upward soil water flux toward the freezing front in the treatment plot was more than double that in the control plot. During the snowmelt period, infiltration of meltwater was unimpeded by the thin frozen layer in the control plot, whereas the relatively thick frozen layer in the treatment plot impeded infiltration and generated 63 mm of runoff. These results clearly show that the changes in the timing and thickness of snow cover deposition can cause a dramatic reduction of frost depth and change in the soil water dynamics.

Studying the winter survival of forage grasses under a changing climate requires models that can simulate the dynamics of soil conditions at low temperatures. We developed a simple model that simulates depth of snow cover, the lower frost boundary of the soil and the freezing of surface puddles. We calibrated the model against independent data from four locations in Norway, capturing climatic variation from south to north (Arctic) and from coastal to inland areas. We parameterized the model by means of Bayesian calibration, and identified the least important model parameters using the sensitivity analysis method of Morris. Verification of the model suggests that the results are reasonable. Because of the simple model structure, some overestimation occurs in snow and frost depth. Both the calibration and the sensitivity analysis suggested that the snow cover module could be simplified with respect to snowmelt and liquid water content. The soil frost module should be kept unchanged, whereas the surface ice module should be changed when more detailed topographical data become available, such as better estimates of the fraction of the land area where puddles may form.

Long-term data from the Hubbard Brook Experimental Forest in New Hampshire show that air temperature has increased by about 1 °C over the last half century. The warmer climate has caused significant declines in snow depth, snow water equivalent and snow cover duration. Paradoxically, it has been suggested that warmer air temperatures may result in colder soils and more soil frost, as warming leads to a reduction in snow cover insulating soils during winter. Hubbard Brook has one of the longest records of direct field measurements of soil frost in the United States. Historical records show no long-term trends in maximum annual frost depth, which is possibly confounded by high interannual variability and infrequency of major soil frost events. As a complement to field measurements, soil frost can be modelled reliably using knowledge of the physics of energy and water transfer. We simulated soil freezing and thawing to the year 2100 using a soil energy and water balance model driven by statistically downscaled climate change projections from three atmosphere-ocean general circulation models under two emission scenarios. Results indicated no major changes in maximum annual frost depth and only a slight increase in number of freeze-thaw events. The most important change suggested by the model is a decline in the number of days with soil frost, stemming from a concurrent decline in the number of snow-covered days. This shortening of the frost-covered period has important implications for forest ecosystem processes such as tree phenology and growth, hydrological flowpaths during winter, and biogeochemical processes in soil.

There widely exists permafrost over Qinghai-Tibetan Plateau. Many roads have to pass permafrost regions. In northeast edge of the plateau, a section of a road has been suffering from frost heave damage for many years. In 2004, a drilling investigation was carried out. It was found that the section of the road was built on a permafrost island, and the soil in active layer belongs to the frost-susceptible silt. Springs on mountain slopes supply the silt with sufficient water. Samples of the silt were taken back to conduct frost heave tests. The frost heave tests were conducted under three moisture conditions, namely sufficient water supply, at liquid limit water content without water supply, and at plastic limit water content without water supply. Test results show that a considerable frost heave appears for the water supply samples, and multi-layer segregated ice is observed. On the other hand, the frost heave is not obvious while keeping water content of samples below its plastic limit. Based on the results, reasonable suggestions were proposed to the road re-construction.

Sensitivity analyses conducted on hydrologic models are useful for understanding the complicated interactions of hydrologic processes and for demonstrating the potential errors resulting from incorrect estimation of input parameters. The effects of typical changes (measurement errors or natural variability) in input parameters on soil freezing as simulated by the Simultaneous Heat and Water (SHAW) model were investigated. The SHAW model simulates the interrelated heat and water transfer within snow, residue, and soil using estimated or measured weather data. Simulated frost depth was found to be very sensitive to small changes in air temperature (1° C) and initial snow depth (10 cm). Simulated frost depth was also potentially sensitive to the specified soil temperature for the lower boundary depending on the proximity of frost depth to the depth of the simulated profile. Site, residue soil characteristics having the greatest impact on simulated frost were slope, thickness of the residue layer, thermal conductivity of soil particles, soil bulk density, and a surface roughness parameter. Soil hydraulic parameters had little effect on frost depth, but had a large impact on water movement toward the zone of freezing and ice content of the frozen soil.

[1] Frost boils in the Arctic are a manifestation of patterned ground in the form of nonsorted circles. Active frost boils involve convection of water through the soil that can bring basic salts from depth to the surface. As such, active frost boils can mitigate acidification and thereby strongly influence the type of vegetation supported by Arctic soils. The presence or absence of active frost boils is thought to play a pivotal role in establishing the sharp demarcation between moist nonacidic tundra (MNT) and moist acidic tundra (MAT) in the Arctic. The focus of this paper is to corroborate the predictions of a mathematical model that relates observable patterned ground features to ecosystem parameters with observations at the field sites along the North American Arctic Transect (NAAT) established by the Biocomplexity of Patterned-Ground Ecosystems Project. Model predictions indicate that recurrent one-dimensional frost heave can become unstable and evolve into multidimensional differential frost heave (DFH). A laboratory frost heave simulation produced a 28-cm pattern in an active layer of 10 cm, which agrees with linear stability theory predictions. A finite element solution predicts three-dimensional patterns with approximately 3-m spacing develop in a 1.0-m active layer with a surface n factor of 0.35, which agrees well with field observations from the NAAT. The lack of significant frost boil activity in the MAT is a result of suppression of DFH owing to denser surface vegetation characterized by low n factors. Prominent active frost boils are observed in the MNT at higher latitudes with more sparse vegetation characterized by higher n factors that promote DFH. However, at the northernmost field sites frost boils cannot be generated even though the n factors are relatively high owing to very rapid freezing conditions that mitigate DFH.