Freezing Melting Research Articles

Tower-based C-band radar measurements of an alpine snowpack

Abstract. To better understand the interactions between C-band radar waves and snow, a tower-based experiment was set up in the Idaho Rocky Mountains for the period of 2021–2023. The experiment objective was to improve understanding of the sensitivity of Sentinel-1 C-band backscatter radar signals to snow. The data were collected in the time domain to measure the backscatter profile from the various snowpack and ground surface layers. The data show that scattering is present throughout the snow volume, although it is limited for low snow densities. Contrasting layer interfaces, ice features and metamorphic snow can have considerable impact on the backscatter signal. During snowmelt periods, wet snow absorbs the signal, and the soil backscatter becomes negligible. A comparison of the vertically integrated tower radar data with Sentinel-1 data shows that both systems have similar temporal behavior, and both feature an increase in backscatter during the dry-snow period in 2021–2022, even during weeks of nearly constant snow depth, likely due to morphological changes in the snowpack. The results demonstrate that C-band radar is sensitive to the dominant seasonal patterns in snow accumulation but that changes in microstructure, stratigraphy, melt–freeze cycles and snow wetness may complicate satellite-based snow depth retrievals.

Polysiphonia morrowii Harvey'nin Biyokimyasal ve Fizyolojik Özellikleri Üzerinde Etkili Bir Parametre: Tuzluluk Stresi

In recent years, rising temperatures due to global climate change can constitute a decrease in salinity in the oceans by causing the ice to melt early and freeze late in its annual cycle and increased precipitation. On the other hand, high temperatures can increase the salinity of seawater locally by enhancing evaporation. It is expected that the changes in salinity of sea water would affect communities of seaweeds. In this study, Polysiphonia morrowii Harvey samples were collected from Altıntaş station in the Gulf of Gemlik in April 2013, and cultured in mediums with four different salt concentrations (10‰, 23‰, 33‰, 42‰). The changes of this species in the amounts of total protein, total phenol, phycocyanin (PC), phycoerythrin (PE), chlorophyll-a (Chl a), water-soluble antioxidant, oil-soluble antioxidant, total solid organic matter and the activity of the carbonic anhydrase were determined. The study clearly showed that studied biochemical and physiological properties of the species were affected by salinity changes. It is also detected that P. morrowii is a tolerant species that can adapt to changing salinity conditions with various defense strategies.

Simulation of Ice Melting–Freezing in the Problem of Fluid Flow Past a Small Irregularity

Simulation of Ice Melting–Freezing in the Problem of Fluid Flow Past a Small Irregularity

Ultra-rapid freezing of Al and Al–Si12: Formation of nanocrystals and metastable solid solutions

We report effects of ultra-rapid melt–freeze cycles on pure aluminum and on aluminum alloy 4047 (which contains ≈12 at. % Si) caused by a series of ≈15 ns-long pulses of 308-nm laser light at a fluence of around 3 J cm−2. This process achieves a calculated cooling rate of about 109 K s−1, which is much faster than splat cooling or melt spinning. The focus here is on the reduction in the lattice parameters of the resulting crystals. In pure aluminum, this reduction is caused by the formation of nanocrystals, whose sizes are determined by the magnitude of the change in the lattice parameter. However, for the alloy, previous investigators have also found a comparable reduction in the lattice parameter but attributed it, instead, to the formation of metastable solutions of Si in Al. We find that the effect in the Al–Si alloy is caused by an unknown combination of size and composition dependence, but it is possible that there is no size dependence in the alloy.

Detoxification of arsenite by iodide in frozen solution

The oxidation of arsenite (As(III)) to arsenate (As(V)) has received significant attention because it helps mitigate the hazardous and adverse effects of As(III) and subsequently improves the effectiveness of arsenic removal. This study developed an efficient freezing technology for the oxidative transformation of As(III) based on iodide (I−). For a sample containing a very low concentration of 20 μM As(III) and 200 μM I− frozen at −20 °C, approximately 19 μM As(V) was formed after reaction for 0.5 h at pH 3. This rapid conversion has never been achieved in previous studies. However, As(V) was not generated in water at 25 °C. The acceleration of the oxidation of As(III) by I− in ice may be attributed to the freeze-concentration effect. During freezing, all components (i.e., As(III), I−, and protons) are highly concentrated in the ice grain boundary regions, resulting in thermodynamically and kinetically favorable conditions for the redox reaction between As(III) and I−. The efficiency of the oxidation of As(III) using I− increased at high I− concentrations and low pH values. The low freezing temperature (below −20 °C) hindered the oxidative transformation of As(III) by I−. The efficiency of the oxidation of As(III) significantly increased using a fixed initial concentration of I− by subjecting the system to six freezing–melting cycles. The outcomes of this study suggest the possibility of the self-detoxification of As(III) in the natural environment, indicating the potential for developing an eco-friendly method for the treatment of As(III)-contaminated areas in regions with a cold climate. It also demonstrates radical remediation to almost completely remove a very small amount of As(III) that was input in As(III)-contaminated wastewater detoxification, a benchmark that existing methods have been unable to achieve.

Photothermal materials with energy-storage properties provide an energy-saving design for highly efficient anti-icing/deicing applications

All-weather, high-efficiency solar photothermal anti-icing/deicing systems are of great importance for solving the problem of ice accumulation on outdoor equipment surfaces. In this study, a photothermal phase change material with a micro-porous structure (MP@PPCM) is prepared via salt-template and melt-blending methods. Owing to the synergistic effect of the latent heat released from the phase change material and the thermal-insulation effect of the internal micro-porous structure, MP@PPCM exhibits a low cooling rate and a high equilibrium temperature during the cooling process. In addition, MP@PPCM exhibits excellent photothermal conversion performance under light illumination, providing the basis for highly efficient anti-icing/deicing. Notably, the single droplet icing and melting results show that the droplet has the longest icing delay time and the shortest melting time on the MP@PPCM sample compared to that on the other samples analyzed. Furthermore, day–night alternation, multiple freezing–melting, and chemical stability tests verify the outdoor applications potential of MP@PPCM. The study results provide a way to prepare high-efficiency photothermal anti-icing/deicing materials in the absence of light conditions.

Preparation and evaluation of polyvinyl alcohol hydrogels with zinc oxide nanoparticles as a drug controlled release agent for a hydrophilic drug

Abstract We report the preparation and application of ZnO/PVA nanocomposite hydrogel containing diclofenac sodium drug (DS) as a drug delivery system. The purpose of designing the nanocomposite hydrogels is to reduce the frequency of use and its side effects, and increase the effect of the drug. The desired nanocomposite hydrogel were prepared through the freezing–melting cycle. The structure and morphology were determined by FTIR and SEM, respectively. The gel fraction increased with adding the nanoparticles, from 67.49 % to 97.69 %. This amount also reaches 97.97 % by adding the drug. The degree of swelling decreased with increasing the amounts of nanoparticles and DS (998 % for PVA-710 % for 1 wt% DS). Based on the result of antibacterial properties and biocompatibility, the inhibition zones around the sample were about 2 mm for Staphylococcus aureus and for Escherichia coli. The cell viability of hydrogel increased from 66.02 % to 79.84 % with increasing the amount of DS. The biodegradation of PVA, is also higher (5–27.17 %) than ZnO/PVA with (3.8–20.2 %) and without (4–23.53 %) drug. The modeling results showed that Peppas–Korsmeyer is a good model for DS release from ZnO/PVA and the diffusion mechanism of DS is Fickian. In this way, we introduced an effective system for drug delivery.

High-Performance Forecasting of Spring Flood in Mountain River Basins with Complex Landscape Structure

We propose the methodology of building the process-driven models for medium-term forecasting of spring floods (including catastrophic ones) in the mountainous areas, the hydrological analysis of which is usually much more complicated in contrast to plains. Our methodology is based on system analytical modeling of complex hydrological processes in 34 river basins of the Altai-Sayan mountain country. Consideration of 13 types of landscapes as autonomous hydrological subsystems influencing rivers’ runoff (1951–2020) allowed us to develop the universal predictive model for the most dangerous April monthly runoff (with ice motion), which is applicable to any river basin. The input factors of the model are the average monthly air temperature and monthly precipitation for the current autumn–winter period, as well as the data on the basin landscape structure and relief calculated by GIS tools. The established universal dependences of hydrological runoffs on meteorological factors are quite complex and formed under influence of solar radiation and physical–hydrological patterns of melting snow cover, moistening, freezing, and thawing of soils. The model shows the greatest sensitivity of April floods to the landscape composition of river basins (49% of common flood variance), then to autumn precipitation (9%), winter precipitation (3%), and finally, to winter air temperature (0.7%). When it is applied to individual river basins, the forecast quality is very good, with the Nesh–Sutcliffe coefficient NSE = 0.77. In terms of the accuracy of process-driven predictive hydrological models for the mountainous areas, the designed model demonstrates high-class performance.

Diffusion of Circumpolar Deep Water Towards Antarctica

AbstractWarm, salty Circumpolar Deep Water (CDW) is recognized as the primary driver for Antarctic glacial melt, but the mechanism by which it reaches the continental shelves remains highly uncertain from an observational standpoint. With the scarcity of eddy flux estimation in the Antarctic margin, we quantify the isopycnal diffusivity of CDW using hydrographic variability and satellite altimetry under the mixing length framework. For comparison, the spiciness and thickness are used as isopycnal tracers, and the two tracers yield qualitatively similar estimates. Over the Antarctic Circumpolar Current (ACC), variation of mixing length is generally aligned with the jet‐induced mixing suppression, including in areas where topography blocks the jet's influence. In contrast, the mixing length does not depend on the mean flow in the subpolar zone, likely reflecting the relatively quiescent flow regime. The estimated isopycnal diffusivity ranges from 100 to 500 m2 s−1 south of the ACC. The eddy diffusivity tends to be enhanced where the gradient of isopycnal thickness becomes small and CDW intrudes onshore. The cross‐slope eddy CDW flux is estimated, and the associated onshore heat flux across is calculated as ∼3.6 TW in the eastern Indian sector. The eddy heat flux and coastal solar heating are generally balanced with cryospheric heat sinks including glacial melting and surface freezing, suggesting that the eddy advection is substantial for the onshore CDW flux. The thickness field is essential for determining mixing length and eddy fluxes in the subpolar zone, however this is not the case in the ACC domain.

Highly Stable MXene-Based Phase Change Composites with Enhanced Thermal Conductivity and Photothermal Storage Capability

To improve the solar energy storage efficiency and thermal conductivity, we developed stable 3D-Ti3C2Tx framework-supported composites as phase change materials (FCPCMs) fabricated by the spatial confining forced network assembly (SCFNA) method. The 3D-Ti3C2Tx framework was constructed by decomposition of a compressed mixture of NH4HCO3 and Ti3C2Tx nanosheets. The controllable porous structure of the 3D-Ti3C2Tx framework and hydrogen bonds between -OH groups (or -F groups) on the surface of MXene and the long chain of PEG benefited the good impregnation of PEG into the framework with good compatibility. Therefore, the developed PCM composites exhibited satisfactory phase change enthalpy in the range of 93.36–119.11 J/g. Compared with PEG8000, the thermal conductivity of the composite with loading 40 wt % of 3D-Ti3C2Tx increased from 0.166 to 1.733 W/(m·K). The improvement of the thermal conductivity is mainly derived from the thermal conduction path provided by the stable 3D-Ti3C2Tx framework. Based on the spatial confining forced network assembly, FCPCMs presented good shape stabilization and thermal reliability in 200 melting–freezing cycles. Benefiting from the construction of the 3D-Ti3C2Tx thermal conductivity path, the fast temperature increase rate under light irradiation is the highlight of FCPCMs. It is noted that FCPCMs exhibit both good photothermal conversion and energy storage efficiency, with the photothermal conversion and storage performance η as high as 95%. Consequently, the developed PCM composites in this work exhibited tremendous application potential in the solar energy utilization field.

Investigation of using conductive asphalt concrete with carbon fiber additives in intelligent anti-icing systems

ABSTRACT In winter, ice on the roads causes traffic accidents and congestion. In recent years, various techniques have been developed to provide more effective, efficient, and environmentally friendly solutions to the problem of road icing. One of these is electrically conductive asphalt concrete (CAC). This study aims to develop an intelligent anti-icing system by increasing the conductivity and mechanical properties of asphalt concrete. Two different conductive asphalt series were produced. Series 1 uses a binder modified with 3% styrene butadiene styrene (SBS) block copolymer and Series 2 uses a binder modified with both 3% SBS and 14% carbon black (CB). In both series, 0.3% carbon fiber (CF) by weight was added to the dry mixture. Thermal dissipation status, ice melting performance, freezing, and electrical conductivity heating cycle tests were conducted. The long-term mechanical and conductivity performances of CAC specimens were assessed with pre-and post-cycle experiments. CAC, developed for its conductivity and mechanical properties, was integrated with the intelligent anti-icing system. A comparative cost analysis was also performed to assess conventional asphalt concrete and the CAC. The binder phase was found to contribute to the mixture conductivity. Such systems can be integrated with Intelligent Transportation Systems (ITS).

The influence of Pseudomonas syringae on water freezing and ice melting.

Pseudomonas syringae is a widely spread plant pathogen known to have ice-nucleating proteins that serve as crystallization sites promoting ice growth at near-zero temperatures. Three temperatures that characterize water freezing and ice melting are (i) the freezing point of water, (ii) the temperature of coexistence of ice and water, and (iii) the melting point of ice. Here we show the influence of different concentrations of P. syringae on these three parameters. P. syringae appears to affect both the freezing point of water and the temperature of the coexistence of ice and water. Additionally, we propose a research technique for studying the freezing/melting process that is simple and requires no complex equipment.

Assessment of freeze melting technology for brine concentration

Assessment of freeze melting technology for brine concentration

The impact of the freeze–melt cycle of land-fast ice on the distribution of dissolved organic matter in the Laptev and East Siberian seas (Siberian Arctic)

Abstract. Permafrost degradation in the catchment of major Siberian rivers, combined with higher precipitation in a warming climate, could increase the flux of terrestrially derived dissolved organic matter (tDOM) into the Arctic Ocean (AO). Each year, ∼ 7.9 Tg of dissolved organic carbon (DOC) is discharged into the AO via the three largest rivers that flow into the Laptev Sea (LS) and East Siberian Sea (ESS). A significant proportion of this tDOM-rich river water undergoes at least one freeze–melt cycle in the land-fast ice that forms along the coast of the Laptev and East Siberian seas in winter. To better understand how growth and melting of land-fast ice affect dissolved organic matter (DOM) dynamics in the LS and ESS, we determined DOC concentrations and the optical properties of coloured dissolved organic matter (CDOM) in sea ice, river water and seawater. The data set, covering different seasons over a 9-year period (2010–2019), was complemented by oceanographic measurements (T, S) and determination of the oxygen isotope composition of the seawater. Although removal of tDOM cannot be ruled out, our study suggests that conservative mixing of high-tDOM river water and sea-ice meltwater with low-tDOM seawater is the major factor controlling the surface distribution of tDOM in the LS and ESS. A case study based on data from winter 2012 and spring 2014 reveals that the mixing of about 273 km3 of low-tDOM land-fast-ice meltwater (containing ∼ 0.3 Tg DOC) with more than 200 km3 of high-tDOM Lena River water discharged during the spring freshet (∼ 2.8 Tg DOC yr−1) plays a dominant role in this respect. The mixing of the two low-salinity surface water masses is possible because the meltwater and the river water of the spring freshet flow into the southeastern LS at the same time every year (May–July). In addition, budget calculations indicate that in the course of the growth of land-fast ice in the southeastern LS, ∼ 1.2 Tg DOC yr−1 (± 0.54 Tg) can be expelled from the growing ice in winter, together with brines. These DOC-rich brines can then be transported across the shelves into the Arctic halocline and the Transpolar Drift Current flowing from the Siberian Shelf towards Greenland. The study of dissolved organic matter dynamics in the AO is important not only to decipher the Arctic carbon cycle but also because CDOM regulates physical processes such as radiative forcing in the upper ocean, which has important effects on sea surface temperature, water column stratification, biological productivity and UV penetration.

NDVI Variations and Its Responses to hydrothermal process in the Naqu River Basin, Qinghai-Tibet Plateau-Alpine Region

Extensive studies have been conducted over the whole year and various seasons to characterize the temporal and spatial changes in vegetation NDVI. However, there are few studies on the variations of NDVI in different soil hydrothermal processes of the alpine region. So we studied the spatial-temporal variation of vegetation cover and its responses to hydrothermal process in the Qinghai-Tibet Plateau-alpine region. Based on the GIMMS NDVI remote sensing images from 1982 to 2015, the temporal and spatial variations of NDVI in the Naqu river basin at different time scales were studied by using maximum synthesis method, and the linear regression. Results show that the vegetation has an overall degradation trend in the Naqu river basin, with primarily moderate and mild degradation degrees. Completely freezing period, completely melting period and freezing process period are the main vegetation degradation periods.

Seasonal transition dates can reveal biases in Arctic sea ice simulations

Abstract. Arctic sea ice experiences a dramatic annual cycle, and seasonal ice loss and growth can be characterized by various metrics: melt onset, breakup, opening, freeze onset, freeze-up, and closing. By evaluating a range of seasonal sea ice metrics, CMIP6 sea ice simulations can be evaluated in more detail than by using traditional metrics alone, such as sea ice area. We show that models capture the observed asymmetry in seasonal sea ice transitions, with spring ice loss taking about 1–2 months longer than fall ice growth. The largest impacts of internal variability are seen in the inflow regions for melt and freeze onset dates, but all metrics show pan-Arctic model spreads exceeding the internal variability range, indicating the contribution of model differences. Through climate model evaluation in the context of both observations and internal variability, we show that biases in seasonal transition dates can compensate for other unrealistic aspects of simulated sea ice. In some models, this leads to September sea ice areas in agreement with observations for the wrong reasons.

Cloud history can change water–ice–surface interactions of oxide mineral aerosols: a case study on silica

Abstract. Mineral aerosol particles nucleate ice, and many insights have been obtained on water freezing as a function of mineral surface properties such as charge or morphology. Previous studies have mainly focused on pristine samples despite the fact that aerosol particles age under natural atmospheric conditions. For example, an aerosol-containing cloud droplet can go through freeze–melt or evaporation–condensation cycles that change the surface structure, the ionic strength, and pH. Variations in the surface properties of ice-nucleating particles in the atmosphere have been largely overlooked. Here, we use an environmental cell in conjunction with nonlinear spectroscopy (second-harmonic generation) to study the effect of freeze–melt processes on the aqueous chemistry at silica surfaces at low pH. We found that successive freeze–melt cycles disrupt the dissolution equilibrium, substantially changing the surface properties and giving rise to marked variations in the interfacial water structure and the ice nucleation ability of the surface. The degree of order of water molecules, next to the surface, at any temperature during cooling decreases and then increases again with sample aging. Along the aging process, the water ordering–cooling dependence and ice nucleation ability improve continuously.

Changing surface radiation and energy budgets of the Hudson Bay Complex using the North American regional reanalysis (NARR) model

Monthly and annual component fluxes of the surface radiation and energy budgets for the two-decade period from 1997 to 2016 are compared with the climate normal period (1981–2010) for the marine system consisting of James Bay, Hudson Bay, Hudson Strait and Foxe Basin using estimates from the North American regional reanalysis model. Reflected solar radiation has declined unevenly, primarily offshore of major rivers, in polynyas and along shore leads, both during earlier melt and later freeze up. Annually, net radiation increases are driven by albedo decreases during the summer. Over 94% of the increases in ocean heat gain during the melt season are due to increases in absorbed sunlight. Large enhanced oceanic heat losses in the late fall are almost entirely consumed by intensified convective losses of both sensible and latent heat. All the seas within the Hudson Bay Complex show a reduced rate of ocean warming over the past two decades. This outcome can be partially reconciled with the observation that all water bodies are experiencing enhanced losses of energy during extended ice-free winters that exceed enhanced gains of energy during the extended ice-free summers. The implications of seasonal changes in ice cover for future climate are discussed.

Development and Long-Term Stability Assessment of Co–C Eutectic Fixed Point for Thermocouple Thermometry

The long-term stability assessment on the Co–C eutectic fixed point cell indigenously developed at CSIR-National Physical Laboratory, India is presented. Metal–carbon eutectic fixed points are promising candidates for the direct traceability to high-temperature thermometry and radiometry. The acceptance of any fixed point as a temperature reference cell depends on its repeatability, reproducibility, and long-term stability. In this paper, we report the detailed investigations on development and realization of Co–C cell and comparison of successive 3-year data to evaluate the long-term stability and robustness of cell. We assigned melting transition temperature to Co–C cell by using Type-S thermocouple, calibrated on ITS-90 fixed points. The cell has been subjected for 270 h of melt–freeze cycle since its construction in 2014 and exhibits excellent thermo-mechanical stability. The Co–C melting transition temperature and measurement uncertainty were estimated by using the same Type-S thermocouple, for 3 years from 2015 to 2017, and overall drift for the cell was estimated to be 0.1 °C, after normalizing the drift of the thermocouple.

Nonlinear Dielectric Effect in the Vicinity of Solid–Liquid Phase Transition of 1-Decanol

The motivation to perform nonlinear dielectric effect (NDE) experiments in the vicinity of the freezing–melting region of 1-decanol was the intention to observe a pretransition anomaly in supercooled liquid, similar to that announced already for nitrobenzene. In the case of 1-decanol the pretransition effects related to supercooling were not observed, but we found interesting NDE behavior in the solid state approaching the melting temperature. To our best knowledge, it is the first time that NDE was measured in the solid state close to solid–liquid phase transition. In our opinion, the observed behavior could be interpreted as an effect of appearance of the rotator phase and premelting.