Sub-freezing Temperatures Research Articles

Evolving Arctic maritime hazards: Declining sea ice and rising waves in the Northwest Passage

The ongoing and projected retreat of Arctic sea ice has garnered international interest toward the utilization of Arctic maritime corridors for shipping, tourism, and development. Yet, with potential for increasing traffic in Arctic regions, it's important to consider additional environmental variables affected by climate change which may threaten maritime operations. Here, we use four climate model projections to produce ocean wave simulations and investigate the future magnitude and seasonality of sea ice risk coupled with wave hazards. Analyzing the potential 5 mo shipping season spanning July to November along the Northwest Passage maritime route between 2020 and 2070, our results show a substantial decline in sea ice risk over the analysis time period, resulting in near open-water conditions along the route for a 5 mo period by 2070. However, as seasonal ice coverage retreats, there is a significant upward trend in wave heights along the route during July and November, with the timing of the greatest wave height shifting away from September toward later in the season. This result is pertinent as the possibility of seasonally unprecedented extreme waves coupled with subfreezing late fall temperatures makes for an especially hazardous environment, thus emphasizing the importance of considering the interaction between evolving sea ice and interdependent hazards when predicting the risks and challenges faced by Arctic maritime operations.

Adaptation to appropriate sub-freezing temperatures through reduction of mycelial porosity and alteration of cell wall composition in Stropharia rugosoannulata

Sub-zero temperatures are avoided for storing mushrooms due to freeze damage. Stropharia rugosoannulata (S. rugosoannulata) often encounter such low temperatures prior to harvest. To preserve S. rugosoannulata, sub-freezing was studied at −2 °C, −6 °C, and −10 °C. The mechanism that caused the differences in the quality was analyzed from the perspective of water distribution and microstructure. The results revealed that at −2 ℃, S. rugosoannulata achieved a firmness and flavor that was comparable to that of the fresh samples. Water migration was observed at −2 ℃. However, at this temperature, S. rugosoannulata exhibited a lower drip loss compared to the fresh samples, and there was no significant variation in the malondialdehyde (MDA) and the electrolyte leakage rate (EL). Despite the swelling of the cells, the mycelial porosity decreased and the cell wall protein and water-soluble polysaccharide content increased to acclimate to the low temperature. In summary, the results of this study imply that it is possible to store S. rugosoannulata at suitable sub-freezing temperatures.

Effect of enzymatic hydrolysis of arabinoxylan on the quality of frozen dough during the subfreezing process.

The objective of this investigation was to examine the impact of enzymatic hydrolysis of arabinoxylan (AX) on frozen dough quality under subfreezing conditions. The dough was subjected to freezing at -40 °C for 2 h and then stored at -9, -12, and -18 °C for 15 days. The water loss, freezable water content, water migration, and microstructure of the dough were measured. The dough containing 0.8% cellulase enzymatically hydrolyzed AX (CAX) required the shortest duration when traversing the maximum ice-crystal formation zone (6.5 min). The dough with xylanase enzymatically hydrolyzed AX (XAX) demonstrated a faster freezing rate than the dough with CAX. The inclusion of both XAX and CAX in the dough resulted in the lowest freezable water loss and reduced freezable water content and free-water content levels, whereas the inclusion of xylanase-cellulase combined with enzymatically hydrolyzed AX resulted in higher free-water content levels. The textural properties of the subfreezing temperature dough were not significantly different from the dough stored at -18 °C and sometimes even approached or surpassed the quality observed in the control group rather than the dough stored at -18 °C. In addition, the gluten network structure remains well preserved in XAX- and CAX-containing doughs with minimal starch damage. The enzymatic hydrolysis of AX from wheat bran can be used as a useful additive to improve the quality of frozen dough. © 2024 Society of Chemical Industry.

Evaluation of a Probabilistic Subfreezing Road Temperature Nowcast System Based on Machine Learning

Abstract Road surface temperatures are a critical factor in determining driving conditions, especially during winter storms. Road temperature observations across the United States are sparse and located mainly along major highways. A machine learning–based system for nowcasting the probability of subfreezing road surface temperatures was developed at NSSL to allow for widespread monitoring of road conditions in real time. In this article, these products were evaluated over two winter seasons. Strengths and weaknesses in the nowcast system were identified by stratifying the evaluation metrics into various subsets. These results show that the current system performed well in general, but significantly underpredicted the probability of subfreezing roads during frozen precipitation events. Machine learning experiments were performed to attempt to address these issues. Evaluations of these experiments indicate reduction in errors when precipitation phase was included as a predictor and precipitating cases were more substantially represented in the training data for the machine learning system. Significance Statement The purpose of this study is to better understand the strengths and weaknesses of a system that predicts the probability of subfreezing road surface temperatures. We found that the system performed well in general, but underpredicted the probabilities when frozen precipitation was predicted to reach the surface. These biases were substantially improved by modifying the system to increase its focus on situations with falling precipitation. The updated system should allow for improved monitoring and forecasting of potentially hazardous conditions during winter storms.

Sediment Transport Beneath a Simulated Partial Ice Cover: Effects of Asymmetric Border Ice

With the onset of winter in cold regions, border ice begins to form, impacting sediment transport rate and distribution. Understanding the effect of ice cover is crucial in regions with prolonged sub-freezing temperatures, as water bodies remain frozen for a considerable part of the year. While the existing literature includes many studies on sediment transport in open channel flow and several studies on completely ice-covered flow, there is limited research on sediment transport in partially ice-covered channels. Addressing this gap, the current study conducted laboratory experiments in a rectangular flume at the Hydraulics Research and Testing Facility, University of Manitoba, Canada. The investigation focused on examining the influence of asymmetric border ice, varying coverage ratios in asymmetric partially ice-covered flow, and changing flow strengths on bedload transport rate and distribution. Additionally, a comparison was made with symmetric partially ice-covered flow conditions. The findings indicate that the presence of asymmetric border ice indeed affected the bedload transport distribution within the channel, causing non-uniform bedload transport distribution across the channel width, with peak values concentrated in the center of the open flow section. Increased asymmetry in border ice leads to greater asymmetry in bedload transport rate distribution. Despite these pronounced differences in bedload transport rate across the channel width, the cross-section-averaged bedload transport rate could still be estimated utilizing the conventional equations, used for open channel flow, fully ice-covered flow, and symmetric partially ice-covered flow, with the effect of ice cover accounted for by incorporating an additional boundary in the calculation of the wetted perimeter, leading to adjustments in the flow strength.

Accuracy evaluation of heat pulse method to determine ice thermal conductivity

The heat pulse (HP) method is among the most widely used methods to measure thermal properties of frozen soil, snow or glaciers. The phase change or ice melting caused by the released heat of the HP method considerably affects the measurement accuracy. Accurate estimation of thermal properties at high subfreezing soil temperatures (e.g., −5–0 °C) remains as a challenge for decades, given that ice melting effects are too complicated to be accounted in the analytical solutions to heat conduction equation. Ice is the fundamental component that determines hydrothermal properties of frozen soil and snow/ice. Therefore, this study observed the different thermal responses of the ice to 6 heating strategies for the heat pulse (combination of 2 heating durations and 3 heating strengths). Meanwhile, the results of finite element method based on COMSOL numerical simulations and two classical analytical solutions were compared. The results showed that accuracy of the results was improved by optimizing the phase change parameters of latent heat term that is included in the governing equation in COMSOL. The main findings are: (1) The numerical simulations and SLS (short-time linear heat source) method well fit the observed temperature change as a function of time at a distance from the heater, ΔT(r, t) curves, with differences in phase change temperatures; (2) Modification of phase change parameters in COMSOL considerably optimized the ΔT(r, t) curve for heating duration over 15 s; (3) The numerical method effectively improved the calculation accuracy of ice thermal conductivity by 9.66% at −5 °C to −1 °C and 17.53% at −3 °C to −1 °C, respectively.

Trade-offs between cold protection and air pollution-induced mortality of China's heating policy.

The winter heating policy in northern China was designed to safeguard households from the harsh subfreezing temperatures. However, it has inadvertently resulted in seasonal spikes in air pollution levels because of the reliance on coal as an energy source. While the loss of life years attributable to mortality from air pollution caused by winter heating has been estimated, the beneficial effect of protection from cold temperatures has not been assessed, primarily due to a lack of individual-level data linking these variables. Our study aims to address this research gap. We provide individual-level empirical evidence that quantifies the impact of protection from cold temperatures and air pollution on mortality, studying 5,334 older adults living around the Huai River during the period between 2000 and 2018. Our adjusted Cox-proportional hazard models show that winter heating was associated with a 22% lower mortality rate (95% CI: 16-28%). Individuals residing in areas without access to winter heating are subjected to heightened mortality risks during periods of cold temperatures. The protective effect is offset by a 27.8% rise attributed to elevated PM2.5 levels. Our results imply that the equilibrium between the effects of these two factors is achieved when PM2.5 concentration exceeds 24.3 µg/m3 (95% CI: 18.4-30.2). Our research suggests that while the existing winter heating policy significantly mitigates winter mortality by lessening the detrimental effects of cold temperatures, future air pollution reduction could provide further health benefits.

Modeling sensitivities of thermally and hydraulically driven ice stream surge cycling

Abstract. Modeling ice sheet instabilities is a numerical challenge of potentially high real-world relevance. Yet, differentiating between the impacts of model physics, numerical implementation choices, and numerical errors is not straightforward. Here, we use an idealized North American geometry and climate representation (similarly to the HEINO (Heinrich Event INtercOmparison) experiments – Calov et al., 2010) to examine the process and numerical sensitivity of ice stream surge cycling in ice flow models. Through sensitivity tests, we identify some numerical requirements for a more robust model configuration for such contexts. To partly address model-specific dependencies, we use both the Glacial Systems Model (GSM) and the Parallel Ice Sheet Model (PISM). We show that modeled surge characteristics are resolution dependent, though they converge (decreased differences between resolutions) at finer horizontal grid resolutions. Discrepancies between fine and coarse horizontal grid resolutions can be reduced by incorporating sliding at sub-freezing temperatures. The inclusion of basal hydrology increases the ice volume lost during surges, whereas the dampening of basal-temperature changes due to a bed thermal model leads to a decrease.

Shape variation and flat plateau formation of a frozen nanofluid droplet

Droplet freezing is a phenomenon of great interest, not only from a fundamental perspective, but also due to its significant contributions to various industrial and ecological processes. Despite the extensive research on pure water droplet freezing, the freezing dynamics of nanofluid droplets have not been investigated to the same extent. It has been observed that frozen nanofluid droplets exhibit a distinctive flat plateau shape at their apex, in contrast to the pointed tip observed in pure water droplets. Our experimental investigation has revealed that when the vertical velocity of nanofluid droplet's freezing front is lower than a critical value, nanoparticles are expelled from the freezing liquid and aggregate at the freezing front to form a particle layer. This layer causes a deviation between the motion direction of the tri-junction line and the interface curve of the unfrozen liquid, resulting in an increased angle growth and the formation of a plateau at the top of the frozen droplet. The critical freezing velocity was found to be independent of the contact angle but showed a slight increase with subfreezing temperature. As the subfreezing temperature rises, the flat plateau of the frozen droplet transitions to a pointed tip. To further explore the freezing dynamics of nanofluid droplets, we conducted a statistical analysis of the cone angle at the apex of the frozen droplets. Our results indicates that in most cases, the cone angle is greater than the universal value observed for pure water droplets. And the cone angle is effected by the droplet volume size and subfreezing temperature.

Susceptibility of winter cut red pine (P. resinosa) stumps to heterobasidion root disease (HRD) infection

Heterobasidion root disease (HRD), a destructive disease of conifers, is a growing management concern. Infection by HRD fungus ( Heterobasidion irregulare) most often occurs when spores, usually produced when temperature is between 5 and 32 °C, land and germinate on freshly cut surfaces. Older stump surfaces are generally unsuitable for colonization, likely due to changes in chemical and physical properties of wood and competitor fungi that limit HRD infection. Stump protectants are effective but not used or recommended in subfreezing temperatures during winter when spores are less common. This study evaluated the potential for older cut stump infection following snowmelt in spring via inoculation of disks collected 7 weeks following initial thinning and exposed to extensive subfreezing temperatures. We found that a surprising number of disks (40%) were successfully colonized with H. irregulare. More research on potential for winter cut conifer HRD infection is warranted as are steps to limit this potential.

Simulated extreme climate event alters a plant-frugivore mutualism

Anthropogenic climate change is contributing to an increase in the frequency of extreme weather events. These extreme events may affect interactions in mutualisms that provide key ecosystem functions, especially when the event is rare for a given system and participants are differentially affected. The tropical hardwood hammocks of Key Largo, Florida, USA are inhabited by a highly specialized endangered rodent, the Key Largo woodrat (Neotoma floridana smalli), which may be an important seed disperser of many native fleshy-fruited plant species. Other potential mammalian dispersers are generalist omnivores, northern raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana), that are less selective. We sought to demonstrate that extreme climate events could alter seed dispersal mutualisms by differentially affecting fruit preference of potential dispersers. We designed a replicated cafeteria-style experiment across the entire range of the Key Largo woodrat with fruit from sixteen native plant species and simulated an extreme climate event by exposing half of the fruits to sub-freezing temperatures. Freezing temperatures are rare in this tropical environment, but increased frequencies of these types of extreme events are predicted with climate change. Using camera traps, we monitored the removal of fruit and seeds by woodrats and the generalist consumers, predicting that changes in fruit quality resulting from exposure to sub-freezing temperatures would reduce preference by the more specialized woodrat relative to its generalist consumers. Indeed, exposure to subfreezing temperatures decreased the probability of fruit and seed removal by woodrats while generalist consumers preferentially removed more of the fruits and seeds exposed to sub-freezing temperatures. These data provide evidence that extreme climate events may affect species preferences for food asymmetrically, which may shift the dynamics of seed dispersal mutualisms. Over time, increasing frequencies of extreme weather events could indirectly affect communities and ecosystem services by shifting interactions between organisms.

Ice Formation during PEM Fuel Cell Cold Start: Acceptable or Not?

Proton exchange membrane (PEM) fuel cell faces the inevitable challenge of the cold start at a sub-freezing temperature. Understanding the underlying degradation mechanisms in the cold start and developing a better starting strategy to achieve a quick startup with no degradation are essential for the wide application of PEM fuel cells. In this study, the comprehensive in situ non-accelerated segmented techniques are developed to analyze the icing processes and obtain the degradation mechanisms under the conditions of freeze-thaw cycle, voltage reversal, and ice formation in different components of PEM fuel cells for different freezing time. A detailed degradation mechanism map in the cold start of PEM fuel cells is proposed to demonstrate how much degradation occurs under different conditions, whether the ice formation is acceptable under the actual operating conditions, and how to suppress the ice formation. Moreover, an ideal starting strategy is developed to achieve the cold start of PEM fuel cells without degradation. This map is highly valuable and useful for researchers to understand the underlying degradation mechanisms and develop the cold start strategy, thereby promoting the commercialization of PEM fuel cells.

An experimental study on icephobicity and hydrophobicity of concrete surface with Dual crystallization Engineered topical treatment

Ice when formed on structural materials exhibits strong bonds, which poses a major challenge to many industries. To remove the ice, the creation of hydrophobic surfaces is used as a passive ice removal technique by reducing ice adhesion. Concrete surfaces treated by Pavix Dual Crystallization Engineered (DCE) material show strong water-repelling characteristics. However, the effect of such treatment on ice adhesion is yet to be studied. To quantify this effect, a series of direct shear tests were performed on concrete specimens with the top surface treated with a Pavix DCE material. TxDOT standard Class S concrete was used as control concrete and mixed at two water-cement ratios, 0.45 and 0.43. Ice-adhesion shear tests were performed on control and DCE-treated concrete disks using a customized direct shear test device at two controlled sub-freezing temperatures, −1 °C and −10 °C. In addition, water-repellent properties and contact angle were measured using a tensiometer under static and receding conditions. Results show reductions of more than 83% in ice adhesion of ice adhesion and more than 98-degree contact angles for DCE-treated concrete specimens. The measured results quantify the anti-icing benefit of DCE treatment and provide insights into understanding the anti-icing mechanism of the treated concrete.

Experimental investigation of sediment transport in partially ice-covered channels

It is important to understand the effects of ice cover on sediment transport in cold climates, where sub-freezing temperatures affect water bodies for a significant part of the year. The literature contains many studies on sediment transport in open channel flow, and several studies on sediment transport in completely ice-covered flow. There has been little or no research on sediment transport in partially ice-covered channels. In the current study, laboratory experiments were done in a rectangular flume to quantify the impact of border ice presence on the sediment transport rate. The effects of ice cover extent and changing flow strengths on sediment transport distribution also were investigated, and the results were compared to those for fully ice-covered and open channel flow. The ice coverage ratios considered were 0 (representing the open water condition), 0.25, 0.50, 0.67, and 1 (representing fully ice-covered flow). The partial ice cover was found to impact the sediment transport distribution within the channel. The effect of ice coverage extent on sediment transport distribution was more significant at lower flow strengths and became negligible at higher flow strengths. The conventional equations for sediment transport in open channel flow and fully ice-covered flow that relate the dimensionless bedload transport rate to the flow strength were found to be applicable to estimate the total cross-section-averaged bedload transport for partially ice-covered flow when modified appropriately. Empirical coefficients for these equations were determined using the experimental data.

Management of multiple frostbite casualties at a burn center: San Antonio, Texas, 12–20 February 2021

BackgroundFrostbite is an insidious disease that normally affects people of cold climates. Winter Storm Uri, which occurred from February 12–20, 2021, created unique metrological conditions for Texas. It caused prolonged sub-freezing temperatures and led to rolling blackouts, affecting 2.8 million Texans including 300,000 people in San Antonio. We report 13 frostbite patients admitted to one burn center during this event. ObjectiveWe aimed to determine the at-risk population for frostbite, to categorize their injury severity, and to describe their treatment. A secondary aim was to describe the rehabilitation management of these patients. MethodsThis is a single-center retrospective study. Each patient’s injuries were assessed by a topographical grading system. Comparisons were made among those who were admitted to the intensive care unit (ICU), admitted to the progressive care unit (PCU), and treated as outpatients. ResultsThirteen patients were identified. Ten (76.9 %) considered themselves homeless, and 9 (69.2 %) were directly exposed to the elements. The median delay between time of injury and presentation to a medical facility was 3 days (IQR 1–6). Only 3 patients presented to a medical facility within 24 h. Six (46 %) sustained grade 2 injuries, 2 (15 %) sustained grade 3 injuries, and 5 (38%) sustained grade 4 injuries. Only one patient met criteria to receive tissue plasminogen activator (tPA), which was discontinued due to hematochezia. Patients admitted to the ICU, when compared to patients admitted to the ward, had a longer length of stay (median 73 days v. 12 days, p = 0.0215), and required more amputations at below-the-knee or higher levels (3 v. 0, p-value 0.0442). ConclusionIn a region unaccustomed and perhaps unprepared to deal with winter storms, the population is particularly vulnerable to frostbite. Lack of awareness of frostbite injuries likely led to the delay in the presentation of patients, which prevented the timely use of tPA. Increasing public awareness may increase readiness.

40.1-GHz sub-freezing 850-nm VCSEL: microwave extraction of cavity lifetimes and small-signal equivalent circuit modeling.

We present an 850-nm vertical-cavity surface-emitting laser (VCSEL) constructed for a wide operating temperature range from 25°C to -50°C sub-freezing temperature, demonstrating 40.1-GHz at -50°C. The optical spectra, junction temperature, and microwave equivalent circuit modeling of a sub-freezing 850-nm VCSEL between -50°C and 25°C are also discussed. Reduced optical losses, higher efficiencies, and shorter cavity lifetimes at sub-freezing temperatures are the leading causes of the improved laser output powers and bandwidths. The e-h recombination lifetime and the cavity photon lifetime are shortened to 113 and 4.1 ps, respectively. Could potentially supercharge VCSEL-based sub-freezing optical links for applications in frigid weather, quantum computing, sensing, aerospace, etc.

Wind tunnel experiment and thermodynamic modeling for dry-snow accretion on a heated surface

Wind tunnel experiments and modeling of dry-snow accretion on a heated surface were performed to estimate the characteristics of dry-snow accretion occurring in sub-freezing temperatures by using cold-climate facilities. The experiments encompassed a wide range of meteorological conditions—air temperature, wind speed, and snow flux—and were conducted over a surface heat flux range of 300–1800 W/m2. The measurements were performed with respect to the snow properties, including growth rate, sticking efficiency, and liquid water content (LWC), and were used to analyze the impact of dry-snow accretion on a heated surface. The experimental results demonstrated the distinct influence of the surface heat flux on the snow accretion process. The sticking efficiency was found to highly correlate with the LWC of the accreted snow and meteorological parameters, and the accreted snow layer was shed from the surfaces when the LWC was slightly above 40%. Moreover, on the basis of heat and mass transfer during the accretion process, models for estimating sticking efficiency and LWC were developed for dry-snow accretion on a heated surface. The effects of convective cooling and evaporation of liquid water inside the accreted snow were incorporated, and the models were cross-validated with the experimental results. The equation was applied to the determination of the minimum value for sticking efficiency, and a linear proportional relation between sticking efficiency and meteorological parameters was demonstrated.

Phytohormones regulate the non-redundant response of ω-3 fatty acid desaturases to low temperatures in Chorispora bungeana

To explore the contributions of ω-3 fatty acid desaturases (FADs) to cold stress response in a special cryophyte, Chorispora bungeana, two plastidial ω-3 desaturase genes (CbFAD7, CbFAD8) were cloned and verified in an Arabidopsis fad7fad8 mutant, before being compared with the microsomal ω-3 desaturase gene (CbFAD3). Though these genes were expressed in all tested tissues of C. bungeana, CbFAD7 and CbFAD8 have the highest expression in leaves, while CbFAD3 was mostly expressed in suspension-cultured cells. Low temperatures resulted in significant increases in trienoic fatty acids (TAs), corresponding to the cooperation of CbFAD3 and CbFAD8 in cultured cells, and the coordination of CbFAD7 and CbFAD8 in leaves. Furthermore, the cold induction of CbFAD8 in the two systems were increased with decreasing temperature and independently contributed to TAs accumulation at subfreezing temperature. A series of experiments revealed that jasmonie acid and brassinosteroids participated in the cold-responsive expression of ω-3 CbFAD genes in both C. bungeana cells and leaves, while the phytohormone regulation in leaves was complex with the participation of abscisic acid and gibberellin. These results point to the hormone-regulated non-redundant contributions of ω-3 CbFADs to maintain appropriate level of TAs under low temperatures, which help C. bungeana survive in cold environments.

Study on Purging Strategy of Polymer Electrolyte Membrane Fuel Cell under Different Operation Conditions

The commercial proton exchange membrane fuel cell (PEMFC) system needs to be equipped with the capacity to survive a harsh environment, including sub-freezing temperatures. The cold start of PEMFC brings about great technical challenges, mainly due to the ice blockage in the components, which seriously hinders the multi physical transmission process. A multiscale, two-dimensional model was established to explore the gas purging in PEMFC under different electrochemical reaction intensities. The results indicate that the optimal case is obtained by B3-1 with a power density of 0.796 W cm−2, and the power density increases first and then decreases, followed by stoichiometric flow ratio (ξ) changes. It is worth noting that the water mole fraction in the PEM is closely related to the water concentration gradient. However, the differences in the initial water distribution in porous media have little bearing on the condensed water in the gas channel, and the liquid water in the gas diffusion layer (GDL) is preferably carried away ahead of other porous parts. The results also show that the increase in the purge speed and temperature can remove the excess water on GDL and the catalytic layer in a short time. For a nitrogen-based purge, the operating condition in case B3-1 is shown as the best strategy based on the output performance and economic analysis during the shutdown and purge process.

РЕЗУЛЬТАТЫ ИСПЫТАНИЙ СУШКИ УВЛАЖНЕННОЙ ИЗОЛЯЦИИ ТЯГОВЫХ ЭЛЕКТРОДВИГАТЕЛЕЙ ЭЛЕКТРОВОЗОВ НА ОСНОВЕ ЭЛЕКТРОКИНЕТИЧЕСКИХ ЯВЛЕНИЙ В УСЛОВИЯХ ДЕПО

The testing results of electroosmotic drying of humidified insulation of traction electric engines of electric locomotives in the conditions of a service locomotive depot are presented in the article. The technology of electroosmotic drying (combined with electrocaloriferous) during the period of sub-freezing air temperatures, based on the device developed by the authors, is proposed. The testing results indicate up to 60 % reduction in electricity consumption and a reduction in the idle time of electric locomotives at TR-1 by 20 %.