Distribution Of Frost Research Articles

Analysis of Frost Heaving Force in Seasonal Frost Region Tunnels: A Case Study of the Xiangyang Tunnel in China

Frost damage in seasonally frozen regions is a primary factor affecting tunnel safety, with frost heaving forces being the main external cause. Therefore, analyzing and calculating the distribution and magnitude of frost heaving forces on surrounding rock is essential for addressing frost damage in tunnels. When the frost heaving force exceeds the design strength, it can lead to the cracking of the lining concrete and a reduction in the tunnel's load-bearing capacity and support stability, posing serious safety risks during construction and operation. This paper is based on the Xiangyang Tunnel project and is grounded in elasticity theory for deriving the frost heaving force formula. Utilizing the von Mises criterion, it employs finite element software to perform thermal-structural coupling analysis, which provides insights into the temperature distribution within the tunnel and the stress distribution patterns of both the lining and the surrounding rock under the influence of frost heaving forces. In the shallow-buried section of the Xiangyang Tunnel, the maximum frost heaving force on the lining is concentrated at the junction of the arch and the base slab. In the deeply buried sections, the distribution of the frost heaving force in the lining is relatively uniform. In contrast, the surrounding rock's frost heaving force distribution follows a layered pattern from the inside out. Beyond a burial depth of 7 meters, the lining and surrounding rock frost heaving forces gradually decrease, approaching a constant value.

The Impact of Climate Change on the Spatiotemporal Distribution of Early Frost in Maize Due to the Northeast Cold Vortex

The Impact of Climate Change on the Spatiotemporal Distribution of Early Frost in Maize Due to the Northeast Cold Vortex

Power optimization for defrosting heaters in household refrigerators to reduce energy consumption

Power optimization was conducted for the defrosting heaters (conductive and radiant heaters) in a freezer to enhance their performance. The distribution of frost in the evaporator was measured experimentally, and the required defrosting energy corresponding to frost accumulation was calculated. The influence of defrosting heaters on frost was evaluated by measuring the heat quantity of the evaporator. The optimization was carried out such that the two heaters distribute the valid energy to the evaporator minimizing the excessive waste heat. At the optimum heater power, the maximum surface temperature of the evaporator was reduced, and the temperature distribution of the evaporator became uniform. The heater power and defrosting time were reduced through power optimization, thereby increasing the defrosting efficiency up to 6.7%. The effective heater power distribution could be further promoted to other heat exchangers with various heat transfer technologies.

Control of the Interactions Between Stream and Groundwater by Permafrost and Seasonal Frost in an Alpine Catchment, Northeastern Tibet Plateau, China

AbstractWhile the individual effects of permafrost and seasonal frost on the interactions between groundwater and surface water have received much attention, few attempts have been made to investigate the effects of permafrost and seasonal frost together on groundwater flow and its interactions with surface water. In this study, hydraulic, chemical, and isotopic data as well as a Bayesian mixing model were employed to investigate the interactions between streams and groundwater, the contributions of groundwater to the mainstream, and their relationships to the distribution of permafrost and seasonal frost in a representative subcatchment in the headwater region of the Heihe River Basin on the northeastern Qinghai‐Tibet Plateau in China. Our results showed that due to the freezing and thawing of recharge water sources and soils, the groundwater flow and stream flux from the permafrost zone to the seasonal frost zone increased during the thawing period, with maximum values in thawed period, and decreased during the frozen period. These variations affected groundwater recharge in the seasonal frost zone, resulting in dynamic changes in the groundwater table and the hydraulic gradient between the recharge and discharge points in the seasonal frost zone during the different freeze‐thaw periods. Correspondingly, the contribution of groundwater to the mainstream discharge decreased from 95% during the frozen period to 80%–90% during the thawing period. It then decreased to ∼40%–60% of the mainstream discharge during the thawed period and increased to ∼70%–90% during the refreezing period. From the permafrost zone to the seasonal frost zone and the catchment outlet, the aquifers in the piedmont plain of the seasonal frost zone play an important role in maintaining streamflows by switching their hydrological functions, that is, slowly releasing groundwater to maintain the streamflow during the frozen period and rapidly transferring the groundwater to mainstream during the thawed period.

Mapping Io's Surface Composition With Juno/JIRAM

AbstractThe surface composition of Io is dominated by SO2 frost, plus other chemical species identified or proposed over the past decades by combining Earth‐based and space‐based observations with laboratory data. Here we discuss spectroscopic data sets of Io obtained by the Jovian InfraRed Auroral Mapper (JIRAM) spectro‐imager onboard Juno in nine orbits, spanning a 3‐year period. We display average spectral profiles of Io in the 2–5 μm range, and we use band depths derived from those profiles to map the geographic distribution of SO2 frost and other spectral features. This data set allows for an ~22% surface coverage at 58 to 162 km/px and in a broad range of latitudes. Our results confirm the broadly regional SO2‐frost trends already highlighted by Galileo/NIMS. Io's average spectral profiles as well as the mapping of the 4.47‐μm band also confirm that SO2 exists in the 32S16O18O isotopic form. Surprisingly, the mapping performed by JIRAM shows that the absorption band at 2.1 μm is unrelated to SO2 frost, while we map for the first time the depth of the 2.65‐μm band, highlighting regions enriched in this absorber, possibly H2S. JIRAM data confirm that the 3.92‐μm band, likely due to Cl2SO2, is largely related to the SO2 distribution. The correlation between Cl2SO2 and ClSO2, possibly revealed at 4.62 μm, is not equally clear. The simultaneous presence of two very weak spectral features at 4.55 and 4.62 μm suggests that nitrile compounds or tholins may also be present on the surface.

Analytical and numerical analysis for frost heaving stress distribution within rock joints under freezing and thawing cycles

Water-bearing joints within rock engineering in cold areas are often subjected to frost heaving force in cold season due to water–ice phase transition. To evaluate the damage and stability of rock mass in cold regions, a 3D model that considers moisture migration loss during freezing and thawing was established to study the characteristics of frost heaving force within joints. Then, the numerical simulation of cyclic freeze-thawing of water-bearing joints was carried out through equivalent expansion coefficient and particle flow calculation methods. The distribution of frost heaving force in and around the joints was obtained. According to the results of the numerical tests and theoretical calculations, the frost heaving force in joints is basically stable, the tensile stress concentration area appears at the joint tip, and the frost heaving force decreases gradually away from the jointed rock mass area. The frost heaving force decreases considerably with increasing cycle number and moisture migration loss but it increases with increasing mechanical strength and joint geometric size of rock and ice. The comparison between the numerical solution of the equivalent expansion coefficient method and the theoretical solution shows that the force size and distribution law of frost heaving for the two methods are consistent.

ANALYTICAL SOLUTION OF FROST HEAVING FORCE IN NON-CIRCULAR COLD REGION TUNNELS

A complex variable method is presented of stress and displacement problems for non-circular cold region tunnels. The complex variable method considers the non-circle tunnel support, the frost heaving circle and the unfrozen surrounding rock at the same time, making the problem from the single connected domain to multi connected domain problem, and can not directly apply the classical complex function theory to solve the problem of the stress and displacement of the non-circular tunnel. The analytical formula in Zeta plane orthogonal curvilinear coordinate system of non-circular tunnel lining to frozen surrounding rock to unfrozen surrounding rock system is derived by using classical complex variable method and continuity condition with power series and conformal transformation. Then, the frost heaving force and frost heaving deformation of the non-circular cold region tunnel are obtained by conformal transformation. This complex variable method is applied to Zhegushan tunnel research, and the analytical solution of Zhegushan tunnel openning frost heave stress and frost heave displacement is obtained. Comparing the analytical solution with the numerical solution to verify the correctness of the analytical solution. It can be seen from the results that frost heaving force has an obvious influence on the lining, and the additional circumferential stresses caused by frost heaving at the vault, arch foot and arch bottom are significantly increased. The additional normal stresses caused by frost heaving at the vault and both sides of arch shoulder are significantly increased. Because of the geometric configurations of lining, the frost heaving deformation is uneven, which leads to uneven distribution of frost heaving forces. Compared with previous studies, which consider the frost heaving ring as a single ring, the complex variable method is more practical. And the research results were expected to provide a referenced basis for elasto-plastic analysis of cold-region tunnel.

Age constraints of Mercury's polar deposits suggest recent delivery of ice

Surface ice at the poles of Mercury appears as several-m-thick deposits that are composed of nearly pure water. We provide new age estimates of the surfaces of Mercury's polar deposits from combined analyses of Poisson statistics and direct observations of crater densities within permanently shadowed, radar-bright regions imaged by the MESSENGER spacecraft. These age estimates conservatively suggest that ice was delivered to Mercury within the last ∼330 Myr. The geologically young ages suggest that the surfaces have been recently refreshed, and this may be accomplished by the delivery of ice in a young impactor or impactors. A single, recent impactor is more consistent with the relative purity of the ice, as suggested by the Earth-based radar observations. In contrast to ice on Mercury, observations of the lunar poles are suggestive of a highly patchy distribution of surface frost. The patchiness of lunar polar deposits is consistent with long exposure times to the space weathering environment. Given enough time, the polar deposits on Mercury may age into a more heterogeneous spatial distribution, similar to that on the Moon.

Spatial and Temporal Distribution of Frost in Jordan

Surface frost is a permanent natural hazard that affects almost all areas in Jordan. Daily grass minimum temperatures at seven stations representing the three geographic zones (the Jordan Valley, mountains, and desert) in the country were used to carry out the analysis. A set of years ranging from 68 (for Amman Airport) to 24 years was used in this investigation. Data were tested for normality using a variety of robust statistical procedures. The main objective of the present study is to describe the stochastic nature of frost at these stations. Early and late frost and number of frost-free days were extracted in this investigation. Frost in Jordan occurs as early as the beginning of October, and late frost can last until May or even as late as June, as is the case in the southern mountains. The probability of early and late dates of frost is presented for the various stations. Compensation provided by the government should take into account the probability of frost hazard before / after the date of occur...

Experimental investigation of frost formation on a parallel flow evaporator

This paper experimentally studied the frosting process of a folded–louvered-fin, parallel flow microchannel evaporator in a heat pump central air-conditioning system under three conditions, in which three open states of two capillaries were adopted. Surface temperature distribution on evaporator was measured by 16 thermocouples buried on the leeward side. Mesoscale frost formation processes on its front view surface for three different test conditions were observed using a Charge Coupled Device (CCD) camera. The results showed that the surface temperature distribution on the parallel flow evaporator was uneven and initial frost formation generally started on some partial surface areas of the louvered fins whose surface temperature was lowest after the heat pump system running 6 min later under conditions B and C, while the evaporator began to frost after 8 min under condition A. The non-uniform surface temperature distribution caused by the unequal distribution of the refrigerant flux in the flat tubes’ microchannels resulted in uneven distribution of frost. The ice crystals distribution and frost thickness in frost period could be obtained by the digital image processing method in which the initial pictures were converted into binary image. The results indicated that in a thin layer near fins’ surface, ice crystals had relatively high occupancy rate in the frost growing period and full growth period; the occupancy rate of ice crystals decreased almost linearly with the increasing of the frost thickness (frost height), where the decreasing rate in the frost full grown period was less than that in the frost growing period (in 0.1 mm frost thickness condition, the occupancy rate of ice crystals decreased to 58% in the frost growing period, while in the frost full grown period occupancy rate of ice crystals decreased to 90%; and in 0.25 mm frost thickness, they were 0%, 45% respectively). Furthermore, it can be found that the frost thickness increased as the time increasing and then finally reached maximum values of 0.3 mm, 0.35 mm, and 0.32 mm respectively at three conditions.

Plot studies and modelling of hydrology and erosion in southeast Norway

Soil erosion causes environmental problems in the agriculture landscapes of southeast Norway (785 mm y − 1 , 5.3 °C), especially on artificially levelled soils. Plot at five sites located within 60 km of Oslo mostly cultivated with small grain were used. They represented three soils: A) artificially levelled silty clay loam (3 sites); B) clay (1 site); and C) unlevelled loam with high aggregate stability (1 site). Mostly two of the used tillage systems are reported here: Pl-Au (ploughing in autumn, harrowing in spring), No-Au (no tillage in autumn). Winters could be cold, mild or variable. Due to the distribution of rainfall, evaporation and soil frost during the year, most of the surface runoff occurred during winter and early spring, but also in late autumn due to soil saturation by water. Average losses over 7 yr by Pl-Au were: 2700–6350 kg ha − 1 yr − 1 for soil type A, 1043 for type B and 158 for type C. With no tillage in autumn the following losses relative to ploughing autumn were 0.12, 0.2 and 0.66 respectively for A, B and C soils. Erosion risk was highest with autumn tillage, especially on soil A mostly due to the levelling effect. Infiltration capacity were greatest and erodibility lowest on soil type C. Infiltration capacity was less than 1 mm/h at saturation on soil type A causing surface runoff, even with moderate rainfall intensities. The empirical yet dynamic erosion model ERONOR simulated well the average soil losses for soil types and tillage systems over several years and also distributed surface runoff and soil losses throughout the year satisfactorily. The model does not handle processes on a large scale, but still it worked rather well in agricultural watersheds with no appreciable net losses due to large scale processes. The model can point out parcels with a high erosion risk within a watershed, and it can estimate the energy factor R in the Norwegian version of the USLE. The model predicts increased erosion in southeast Norway based on climate predictions of milder and rainier winters.

Rock moisture measurements: techniques, results, and implications for weathering

AbstractRock moisture is an important factor for the intensity and distribution of frost weathering processes. However, quantitative measurements are scarce, which is partly due to the lack of reliable measurement techniques. This paper presents five different techniques for obtaining rock moisture data. While collecting rock pieces and two‐dimensional geoelectric measurements allow determination of the spatial moisture distribution, the temporal variability can be derived from conductivity and time domain reflectometry records. Computer simulations, using rock properties and climatic records as input data, render it possible to clarify the important aspects that are responsible for the moisture distribution. It proved to be advisable to use several methods to check and validate the results.The results, obtained in study areas in the Bavarian Alps, make it clear that direct rainfall is the main source of rock moisture. The influence of snow is limited to the immediate vicinity of the snow fields and is not equally pronounced at different times and positions. Rock moisture levels are higher in summer than they are in winter, since in winter less water is supplied in liquid form. Northerly exposed rockwalls are generally more moist than those exposed in a southerly direction, which is due to the different insolation as well as to the wind direction during rainfall. In every position the rock is, on average, wetter on the inside than it is on the surface. This means that shallow frost cycles, as typical for south‐exposed sites, are not affecting weathering, since they take place at a depth level that is mostly dried out.Numerous spatial and temporal patterns of rockfall found in the same study areas can be explained through variations in rock moisture. Thus, the moisture content of the rock is considered to be one of the major controlling factors of the frost‐shattering rate. Copyright © 2005 John Wiley & Sons, Ltd.

Modelling vertical and lateral water flow in frozen and sloped forest soil plots

Snowmelt runoff from forest land is influenced by the spatial distribution of soil frost which depends on climatic conditions and stand structure. Snow and frost dynamics as well as near-surface runoff and liquid water content in the soil were measured for two years in two small plots located on a slope within a subalpine spruce stand. These measurements were used to calibrate the one-dimensional water and heat transport model SOIL by only fitting three snow- and two soil-related parameters. The simulated snow and frost dynamics agreed well with field data. The partitioning of snowmelt water into lateral runoff and vertical percolation at the snowpack bottom was best represented assuming that downward water flow through the frozen layers occurred not only in the liquid phase between soil particles and pore ice (low-flow-domain) but also as microscopic bypass flow in the previously air-filled macropores (high-flow-domain). Simulated near-surface runoff is very sensitive to the impedance factor accounting for a reduced upward water flow in frozen soil layers and also to the heat transfer coefficient controlling the refreezing of water infiltrating through the empty voids. The runoff dynamics differed only slightly when the model was driven by daily instead of hourly weather variables.

Spatial and temporal variability of nocturnal summer frost in elevated complex terrain

This paper presents an investigation of summer night temperatures as influenced by a sharply undulating terrain, with a view towards the consequences of summer frost on forest regeneration in thermally marginal areas. The focus is on the presentation of the spatial distribution of monthly mean frost (MMF) in an elevated frost prone area, located approximately 100 m below the timber-line in the southern Swedish Scandes. The MMF is defined as the lowest temperature over a 4 h period at each location on each frost occasion in the study area which is then summed up and averaged for each month of the growing season. Geostatistics (kriging) is used for modelling the MMF distribution in June, July, August and September, 1994. Kriging is essentially a weighted moving average technique which aims to estimate the temperature at a given site based on observations at neighboring sites. The results from modelling using two different sampling strategies are compared over a 90,000 m 2 clear-felled area. A lower density of 18 observations is used for sampling on a fixed grid and a higher density of 29 observations aims to cover the spacing of distinct terrain features in the area. The investigated region is characterized by a local topography with sharp vertical variations, i.e. ‘basin and knob’ terrain. The estimated frost patterns are evaluated in relation to a set of typical pre-defined forms in such terrain. It is found that the spatial distribution of low temperatures corresponded well with local terrain forms and that frost is experienced during each month of the vegetative period. However, there are obvious differences in frost intensity and duration. The single most important factor for explaining the frost patterns during the peak of the growing season is the difference in radiative cooling due to the surrounding local terrain. Variations in the cooling rate of up to 6°C h −1 are recorded between sites that are partially screened from solar radiation and sites that are well exposed. Wind shelter provided by the immediate surroundings of a site is also found to have a significant influence on the near-surface temperature. Maximum differences of 3–5°C are maintained between sites with various degrees of shelter at a mean wind speed of 1.5 m s −1. In June, August and September, drainage of cold air is identified as another important process affecting the distribution of frost. It is suggested that the drainage flow is a shallow gravitational cold air flow of a strictly localized nature.

Classification of meteorological conditions to assess the potential for concrete frost formation in boreal forest floors

During spring 1990, 76% of the Lac Laflamme watershed (47∞N, 71∞W), Canada, was covered with substantial amounts of concrete frost in the boreal forest floors (litter, organic layer). Spatial distribution of concrete frost on the watershed was associated with forest floor composition. The objective of this note is to assess the potential for concrete frost formation in the forest floor by classification of different meteorological conditions and to verify if the type of meteorological combination encountered during 1989n1990 was exceptional. Meteorological records at the Montmorency Forest station for air temperature and precipitation from 1965 to 1990 were analyzed and classified to detect events potentially favourable for the development of concrete frost. Each year was divided into two seasons: snow accumulation and spring snowmelt. When we considered together the accumulation and the snowmelt seasons, 21 years showed one or more events susceptible to initiate concrete ice formation. Four of 25 years had meteorological conditions harsher than the accumulation season of 1989n1990. If the meteorological conditions permitting the formation of concrete frost in the forest floor are not exceptional, then we can hypothesize that the formation of concrete frost is not exceptional as well. Resume : Durant le printemps 1990, 76% du bassin du lac Laflamme (47∞N, 71∞W), Canada, Otait recouvert de quantitOs importantes de glace compacte dans ses litires forestires. La distribution spatiale de cette glace Otait associOe ‡ la

Seasonal Nitrogen Cycles on Pluto

A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model was used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters. Volatile transport was confirmed to have a significant effect on Pluto's climate as nitrogen moved around on a seasonal time scale between hemispheres, and sublimed into and condensed out of the atmosphere. Pluto's high obliquity was found to have a significant effect on the distribution of frost on its surface. Conditions that would lead to permanent polar caps on Triton were found to lead to permanent zonal frost bands on Pluto. In some instances, frost sublimed from the middle of a seasonal cap outward, resulting in a “polar bald spot”. Frost which was darker than the substrate did not satisfy observables on Pluto, in contrast to our findings for Triton. Bright frost (brighter than the substrate) came closer to matching observables. Atmospheric pressure varied seasonally. The amplitudes, and to a lesser extent the phase, of the variation depended significantly on frost and substrate properties. Atmospheric pressure was found to be determined both by Pluto's distance from the sun and by the subsolar latitude. In most cases two peaks in atmospheric pressure were observed annually: a greater one associated with the sublimation of the north polar cap just as Pluto receded from perihelion, and a lesser one associated with the sublimation of the south polar cap as Pluto approached perihelion. Our model predicted frost-free dark substrate surface temperatures in the 50 to 60 K range, while frost temperatures typically ranged between 30 to 40 K. Temporal changes in frost coverage illustrated by our results, and changes in the viewing geometry of Pluto from the Earth, may be important for interpretation of ground-based measurements of Pluto's thermal emission.

Mass transfer of supersaturated contaminants in cryogenic helium heat exchangers

A new experimental technique is developed to measure the distribution of frost accumulated inside the passage of a cryogenic helium heat exchanger. The frost is accumulated by condensation of a contaminant on the passage wall during steady-flow operation of the balanced counterflow heat exchanger. The distribution is measured by flushing the accumulated contaminant into a detector at the exit of the passage. A heat source is moved from the cold to the warm end to convert the spatial distribution of the contaminant to concentration as a function of time in the exiting helium stream. When the degree of supersaturation is small, the accumulation distribution agrees reasonably well with the analytical solution without snow formation. As the supersaturation increases, a clear secondary peak in the distribution is observed, which results from the formation of snow in the free stream and its subsequent deposition as frost on the wall. Based on the results, an onset condition is developed for the formation of snow of a supersaturated contaminant in helium.

Methane absorption variations in the spectrum of Pluto

Absolute spectrophotometry of Pluto in the wavelength range of 5600 to 10,500 Å was obtained on 4 nights covering lightcurve phases of 0.18, 0.35, 0.49, and 0.98. The four phases included minimum light (0.98) and one near maximum light (0.49). The spectra reveal significant variations in the absorption depths of the methane bands at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 Å. The minimum amount of absorption was found to occur at minimum light. This variation would imply a 30° change in the column abundance of methane within 3 days. A model employing an anisotropic surface distribution of methane frost and a clear layer of CH 4 gas was developed to explain the variation in absorption strength with rotational phase. The fit to the overall spectrum requires the presence of a frost with particle sizes on the order of a few millimeters. An upper limit of 5.5 m-am is derived for the one-way column abundance of CH 4 gas. An equally good fit to the variation of the 7200-Å band is obtained if the atmosphere is removed from the model entirely.

Cold Air Drainage and Local Distribution of Frost

Cold Air Drainage and Local Distribution of Frost

Studies on the distribution of frost in the Ingelfingen vineyard. [German

Temperature measurements taken at various positions in a 40-hectare hillside vineyard during night frosts in the spring of 1954 are recorded.-Inst. Phys. Met. landw. Hochsch., Hohenheim. (Abstract retrieved from CAB Abstracts by CABI’s permission)