Ice Parameters Research Articles

Effects of flow parameters on thermal performance of an inner-liner anti-icing system with jets impingement heat transfer

The multiple jets impingement heat transfer is widely applied in the wing anti-icing system. It is challenging to apply the similarity criterion to carry out the anti-icing experiments due to the complex flow and heat transfer behavior. In the present study, the full-scale slat model is used to carry out anti-icing experimental researches in a 2 m × 3 m icing wind tunnel of China Aerodynamics Research and Development Center. The effects of icing parameters Liquid Water Content (LWC) and Median Volume Diameter (MVD) and hot air parameters (mass flow rate and temperature) on the thermal performance of an inner-liner anti-icing system with jets impingement heat transfer are studied. The effects of the experimental parameters are analyzed in detail by combining impingement and evaporation heat transfer mechanisms. The impingement hot air mass flow rate dramatically affects the heat transfer performance of the impingement stagnation region within the range of the experimental parameters. The temperature of impingement hot air and that of wing skin are approximately linear correlated. The experimental results show the effects of LWC and MVD on water film formation and runback ice accretion. The formation of water film is analyzed by an analytical method based on the wing skin temperature difference of dry and wet air conditions.

Hydrodynamic Forces Exerting on an Oscillating Cylinder under Translational Motion in Water Covered by Compressed Ice

This paper presents the calculation of the hydrodynamic forces exerted on an oscillating circular cylinder when it moves perpendicular to its axis in infinitely deep water covered by compressed ice. The cylinder can oscillate both horizontally and vertically in the course of its translational motion. In the linear approximation, a solution is found for the steady wave motion generated by the cylinder within the hydrodynamic set of equations for the incompressible ideal fluid. It is shown that, depending on the rate of ice compression, both normal and anomalous dispersion can occur in the system. In the latter case, the group velocity can be opposite to the phase velocity in a certain range of wavenumbers. The dependences of the hydrodynamic loads exerted on the cylinder (the added mass, damping coefficients, wave resistance and lift force) on the translational velocity and frequency of oscillation were studied. It was shown that there is a possibility of the appearance of negative values for the damping coefficients at the relatively big cylinder velocity; then, the wave resistance decreases with the increase in cylinder velocity. The theoretical results were underpinned by the numerical calculations for the real parameters of ice and cylinder motion.

Sea ice decline drives biogeographical shifts of key Calanus species in the central Arctic Ocean.

In recent decades, the central Arctic Ocean has been experiencing dramatic decline in sea ice coverage, thickness and extent, which is expected to have a tremendous impact on all levels of Arctic marine life. Here, we analyze the regional and temporal changes in pan-Arctic distribution and population structure of the key zooplankton species Calanus glacialis and C. hyperboreus in relation to recent changes in ice conditions, based on historical (1993-1998) and recent (2007-2016) zooplankton collections and satellite-based sea ice observations. We found strong correlations between Calanus abundance/population structure and a number of sea ice parameters. These relationships were particularly strong for C. glacialis, with higher numbers being observed at locations with a lower ice concentration, a shorter distance to the ice edge, and more days of open water. Interestingly, early stages of C. hyperboreus followed the same trends, suggesting that these two species substantially overlap in their core distribution area in the Arctic Ocean. Calanus glacialis and C. hyperboreus have been historically classified as shelf versus basin species, yet we conclude that both species can inhabit a wide range of bottom depths and their distribution in the Arctic Ocean is largely shaped by sea ice dynamics. Our data suggest that the core distribution patterns of these key zooplankton are shifting northwards with retreating sea ice and changing climate conditions.

Investigation of model-scale brash ice properties

A brash ice channel is a typical operation condition for ice-going commercial vessels. The Finnish-Swedish Ice Class Rules (FSICR) define the vessels ice class performance requirements particularly in a brash ice channel. The vessel performance can be verified using model tests, which are conducted according to the FSICR guidelines. However, the guidelines define mainly the channel thickness and width. This research examined, which other brash ice parameters influence the brash ice behavior around a ship hull. The study focuses on the brash ice as a material. Based on literature review of earlier research, the author focused on five central parameters: porosity, piece size and distribution, angle of repose, compressibility, and angle of internal friction. These parameters were examined in three different model brash ice types. The results show that different brash ice types have different properties covering all the five investigated parameters. This variation in brash ice properties presumably affect the behavior of brash ice mass around a moving ship hull and the vessel resistance in brash ice indicating a need for better model brash ice standardization to secure consistent channel model test results.

Arctic ocean–sea ice reanalysis for the period 2007–2016 using the adjoint method

AbstractWe present an Arctic ocean–sea ice reanalysis covering the period 2007–2016 based on the adjoint approach of the Estimating the Circulation and Climate of the Ocean (ECCO) consortium. The spatiotemporal variation of Arctic sea surface temperature (SST), sea ice concentration (SIC), and sea ice thickness (SIT) is substantially improved after the assimilation of ocean and sea ice observations. By assimilating additional World Ocean Atlas 2018 (WOA18) hydrographic data, the freshwater content of the Canadian Basin becomes closer to the observations and translates into changes of the ocean circulation and of transports through the Fram and Davis straits. This new reanalysis compares well with previous filter‐based (TOPAZ4) and nudging‐based (PIOMAS) reanalyses regarding SIC and SST. Benefiting from using the adjoint of the sea ice model, our reanalysis is superior to the ECCOv4r4 product considering sea ice parameters. However, the mean state and variability of the freshwater content and the transport properties of our reanalysis remain different from TOPAZ4 and ECCOv4r4, likely because of a lack of hydrographic observations.

A Method for Assessing the State of the Snow and Ice Cover by the Brewster Angle

Introduction. Landing is the most challenging and dangerous part of the helicopter flight. The development of systems facilitating safe landing is a priority task for both Russian and foreign engineering companies. Landing on unprepared sites covered with snow and ice may be determined by the need to deliver cargo and ammunition in combat conditions, during search and rescue operations, evacuations of victims, etc.Aim. Development of a method for remote assessment of the snow and ice cover based on the results of oblique sensing of the underlying surface with a radio signal with vertical polarization.Materials and methods. In the MatLab environment, the authors conducted numerical simulations of Fresnel reflection coefficients of echo signals with vertical polarization in the 40–90 degree sensing range in the operating frequency range when solving the direct and inverse problem of reconstruction of the parameters of snow and ice layers.Results. Intervals of the Brewster angle values were obtained at which the value of the Fresnel reflection coefficient from the boundaries of the snow and ice cover takes minimal. Thus, was found to be – 47...55°, – 55...58° and – 58...61° for dry snow, dry firn and dry ice, respectively. The depth resolution when using an ultra-wideband LFM signal with a frequency from 2 to 8 GHz is about 4 cm. The methodological error in determining the dielectric permittivity of layers by the Brewster angle comprises not more than 3 %.Conclusion. The error in determining the relative permittivity and the depth of k layers under an increase in the RMS values of the noise level from 3.8 to 4.8 with a step of 0.1 for 100 implementations of each with a probability of 0.95 does not exceed 10 %, which confirms the validity of this method. The implementation of which allows you to automate the process of evaluating the possibility of a safe landing, thereby reducing the decision-making time and increasing the level of safety.

Infrared thermal wave detection and compression experiment of accreted ice

Icing environment incurs great inconvenience to production and life. In order to study the physical characteristics of accreted ice, an experimental platform for ice detection is performed in this paper, and the influence of icing parameters is analyzed by using active infrared thermal wave nondestructive detection system and universal mechnical testing machine, we analyze the influence of icing parameters are icing height, icing diameter and freezing time. With the help of the logarithmic function of temperature difference and time in infrared thermal wave experiment, the relationship between the inflection point of stress-strain curve in compression strength tests and icing parameters is discussed. Results show that larger icing height, smaller icing diameter and longer freezing time will delay the turning point of logarithmic temperature difference curve with time; whereas larger icing height, appropriate freezing time and larger icing diameter will enhance the compressive strength of accreted ice. In addition, the strain level is also one of the factors closely related to the compressive strength. These conclusions lay the foundation for further research on the physical characteristics of the infrared detection of ice.

Исследование воздействия подводного взрыва на ледовый покров

The paper presents the results of studies of the features of deformation and destruction of the ice cover affected by a close underwater explosion, as well as by horizontally installed cylindrical shells under the combined action of the explosion and hydrostatic pressure. The research is based on the results of computer simulation of the processes of underwater explosion and ice cover deformation. It is shown that the second pulsation of the bubble exerts a controlling influence on the nature and parameters of the deformation and destruction of the ice cover under the combined action of a close underwater explosion and a large hydrostatic pressure on the shell. The dependence of the ice explosion resistance on the depth and power of the charge is determined. The influence of the main physical parameters of ice on the explosion resistance is revealed. The results of the research can be used for creating structures effectively resisting the effects of a close underwater explosion.

A Comparison of Decimeter Scale Variations of Physical and Photobiological Parameters in a Late Winter First-Year Sea Ice in Southwest Greenland

Small-scale variation in the physical and biological properties of sea ice was examined by collecting nine sea ice cores within 1 m2 in a land-fast first-year ice in southwest Greenland in late winter. Cores were sectioned in four segments and sea ice physical, biological, and photobiological parameters were measured. The main purpose was to explore the decimeter-scale horizontal and vertical variations in common sea ice parameters. ANOVA analyses revealed significant within-core variations for bulk salinity, brine salinity, brine volume, gas volume, chlorophyll a (Chl a), and the maximum light-limited photosynthetic efficiency (α). Only temperature and bulk salinity variations were significant between cores, and no significant variations were found within or between cores for other photobiological parameters. Power analyses were applied to determine the number of replicates needed to achieve a significance at p < 0.05 with sufficient power, and showed a minimum of four and preferably five replicate cores to detect the observed variability in this first-year ice. It is emphasized that these results only apply to this type of first-year ice in late winter/early spring, and that different variations may apply to other types of ice.

Method for the level optimization of vehicle parameters when using fuels of different quality in cold climates

The task of improving the efficiency of a motor vehicle during operation in cold climates is reduced to the task of ensuring integrated optimization of the main engine values and parameters with an unconditional assessment of ICE fuel quality. The task of ICE integrated optimization includes: justification of the choice of the main ICE values, based on the objectives and optimal solution of the tasks of efficient vehicle operation; assessment of the technology level of fuel and determination of its optimal composition; determination of the optimal parameters for the elements of ICE subsystems. Based on the proposed method for level optimization of ICE parameters when using fuels of different quality, an automated diesel fuel quality control system for vehicles used in regions with cold climates in the form of software was developed.

Estimation of sea ice parameters using an assimilated sea ice model with a variable drag formulation

In this work, sea ice concentrations in the regions of Baffin Bay, Hudson Bay, the Labrador Sea and the Gulf of St. Lawrence were estimated using a standalone regional configuration of Los Alamos Sea ice Model, CICE. A sensitivity analysis of the mixed layer depth criteria that affects the predicted sea ice formation/ablation has been carried out to tune the model. Sea ice concentration from AMSR2 OSISAF, sea ice edge from SSMIS/ASCAT OSISAF, and sea surface temperature from OISST AVHRR-only products were then assimilated into the tuned model using a combined optimal interpolation method. Extending previous studies, which used a constant drag formulation in their assimilation schemes, we use a variable drag formulation to represent the friction associated with effective sea ice surface roughness at the ice–atmosphere and ice–ocean interfaces. The variable drag coefficient is estimated from properties of the sea ice cover such as the ice concentration, the vertical extent and area of the ridges, the freeboard, the floe draft, the size of floes and melt ponds. The new features of the assimilated model include tracers to estimate ridged ice, level ice, melt ponds, freeboard, sail height and keel depth. The estimates of ice concentration from the assimilated models are then compared with the ice concentration product from the Canadian Ice Service. The results show that the updates provided to the tracers through the assimilation of sea ice products are reasonable and the model estimates of ice concentration from the assimilated models are better than the non-assimilated model estimates. Finally, the estimates of updated sea ice parameters such as ridged ice area, volume and ice thickness are compared with the estimates from non-assimilated models and the literature to verify the results.

Parameter optimization in sea ice models with elastic–viscoplastic rheology

Abstract. The modern sea ice models include multiple parameters which strongly affect model solution. As an example, in the CICE6 community model, rheology and landfast grounding/arching effects are simulated by functions of the sea ice thickness and concentration with a set of fixed parameters empirically adjusted to optimize the model performance. In this study, we consider the extension of a two-dimensional elastic–viscoplastic (EVP) sea ice model using a spatially variable representation of these parameters. The feasibility of optimization of the landfast sea ice parameters and rheological parameters is assessed via idealized variational data assimilation experiments with synthetic observations of ice concentration, thickness and velocity. The experiments are configured for a 3 d data assimilation window in a rectangular basin with variable wind forcing. The tangent linear and adjoint models featuring EVP rheology are found to be unstable but can be stabilized by adding a Newtonian damping term into the adjoint equations. A set of observation system simulation experiments shows that landfast parameter distributions can be reconstructed after 5–10 iterations of the minimization procedure. Optimization of sea ice initial conditions and spatially varying parameters in the stress tensor equation requires more computation but provides a better hindcast of the sea ice state and the internal stress tensor. Analysis of inaccuracy in the wind forcing and errors in sea ice thickness observations show reasonable robustness of the variational DA approach and the feasibility of its application to available and incoming observations.

The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness

Abstract. We offer a view of the Antarctic sea ice cover from lidar (ICESat-2) and radar (CryoSat-2) altimetry, with retrievals of freeboard, snow depth, and ice thickness that span an 8-month winter between 1 April and 16 November 2019. Snow depths are from freeboard differences. The multiyear ice observed in the West Weddell sector is the thickest, with a mean sector thickness > 2 m. The thinnest ice is found near polynyas (Ross Sea and Ronne Ice Shelf) where new ice areas are exported seaward and entrained in the surrounding ice cover. For all months, the results suggest that ∼ 65 %–70 % of the total freeboard is comprised of snow. The remarkable mechanical convergence in coastal Amundsen Sea, associated with onshore winds, was captured by ICESat-2 and CryoSat-2. We observe a corresponding correlated increase in freeboards, snow depth, and ice thickness. While the spatial patterns in the freeboard, snow depth, and thickness composites are as expected, the observed seasonality in these variables is rather weak. This most likely results from competing processes (snowfall, snow redistribution, snow and ice formation, ice deformation, and basal growth and melt) that contribute to uncorrelated changes in the total and radar freeboards. Evidence points to biases in CryoSat-2 estimates of ice freeboard of at least a few centimeters from high salinity snow (> 10) in the basal layer resulting in lower or higher snow depth and ice thickness retrievals, although the extent of these areas cannot be established in the current data set. Adjusting CryoSat-2 freeboards by 3–6 cm gives a circumpolar ice volume of 17 900–15 600 km3 in October, for an average thickness of ∼ 1.29–1.13 m. Validation of Antarctic sea ice parameters remains a challenge, as there are no seasonally and regionally diverse data sets that could be used to assess these large-scale satellite retrievals.

Effect of air parameters on ice sublimation in ice rink

This study aims at the sublimation rate of ice and analyzes the influence of supply air and ice parameters on ice surface smoothness. The sublimation rate can be expressed as the product of the sublimation coefficient and humidity ratio difference. COMSOL Multiphysics is adopted as a simulation tool to calculate the associated ice sublimation rate. In ice rinks, the sublimation coefficient is 0.1–0.2 mm/(h·kPa), and the sublimation rate is 0–0.07 mm/h. The results show that the main factor affecting the sublimation coefficient is air velocity over the ice surface. Therefore, the ice sublimation can be decreased by reducing air velocity and decreasing humidity ratio difference between the air and ice surface. The aforementioned findings were applied in an actual curling venue to reduce the sublimation of the ice surface, and the accumulated sublimation within 10 h was reduced from 0.24 mm to 0.016 mm, which effectively solved the problem of ice surface unevenness. This study working on the ice sublimation rate provides inspiration for maintaining the ice stability in ice rinks and improving the quality of venues.

Mapping Sea Ice Surface Topography in High Fidelity With ICESat‐2

AbstractThe Advanced Topographic Laser Altimeter System on Ice, Cloud and land Elevation Satellite 2 (ICESat‐2) offers a new remote sensing capability to measure complex sea ice surface topography. We demonstrate the retrieval of six sea ice parameters from ICESat‐2/Advanced Topographic Laser Altimeter System data: surface roughness, ridge height, ridge frequency, melt pond depth, floe size distribution, and lead frequency. Our results establish that these properties can be observed in high fidelity, across broad geographic regions and ice conditions. We resolve features as narrow as 7 m and achieve a vertical height precision of 0.01 m, representing a significant advance in resolution over previous satellite altimeters. ICESat‐2 employs a year‐round observation strategy spanning all seasons, across both the Arctic and Southern Oceans. Because of its higher resolution, coupled with the spatial and temporal extent of data acquisition, ICESat‐2 observations may be used to investigate time‐varying, dynamic, and thermodynamic sea ice processes.

Mid-frequency propagation and reverberation time series ina deep ice-covered ocean: Modeling and data analysis

Mid-frequency (3.5 kHz) pulses (5 pings, 5 s-long, one per minute) were radiated by an omnidirectional source of opportunity in a deep (3 km) Arctic ocean at 30m depth under ice during the ICEX14 experiment, ALAS component [Williams et al., IEEE-JOE 43, 145–159 (2018)]. Data analysis and modeling results are presented for normalized (re source level) acoustic intensityreceived by an omnidirectional hydrophone located at a 719 m distance from and the same depth as the source. Received time series showed a clear direct blast signal followed by an about 30 s-long reverberation coda. Modeling of the under-ice propagation shows that magnitude of the direct signal is strongly affected by presence of a weak near-surface (within 50 m depths) acoustic channel and by reflectivity of the ice, controlled by its physical properties and acoustical parameters, particularly the ice layer thickness. Analysis of the reverberation coda shows effects of reflections and scattering from rough and/or heterogeneous bottom, as well as reflectivity of the ice layer. Some other effects that may be caused by variability of the sound speed profile and absorption in water are considered as well. Possibilities of inversions for water column, bottom and ice parameters based on this and similar experiments are discussed. [Work supported by ONR.]

Relationships between the Baltic Sea ice extent and ice parameters in the sheltered basins of the southern Baltic coast

Abstract In the study, archive data on the maximum annual ice extent in the Baltic Sea (MIB) for the period 1961–2018 were used. They were obtained from the FIMR database. Data on ice parameters for the four largest southern Baltic coastal lakes: Jamno, Bukowo, Gardno and Łebsko, and for Szczecin, Puck, and Vistula Lagoons, come from the Maritime Branch of Institute of Meteorology and Water Management – National Research Institute (in Polish: Instytut Meteorologii i Gospodarki Wodnej – Panstwowy Instytut Badawczy, IMGW-PIB) in Gdynia. The time series for the lakes cover the years from 1960 to 2018, and for the lagoons – from 1946 to 2018. Three ice parameters were selected for this study: the number of days with ice, the duration of the ice season and the maximum ice thickness for a given winter. Relationships between the selected ice parameters for the studied basins and the MIB were examined using correlation and regression methods. Correlations between the MIB and values of the ice parameters for the lakes and the southern Baltic coastal lagoons do not differ significantly. Considerable differences are observed amongst the correlation coefficients for individual ice parameters and the MIB. Larger differences are found in relationships between the values of individual ice parameters in the sheltered basins and the MIB. The strongest correlation with the MIB is observed for the maximum ice thickness and the number of days with ice.

Performance evaluation of electrothermal anti-icing systems for a rotorcraft engine air intake using a meta model

A meta model was developed to evaluate the performance of electrothermal anti-icing systems for a rotorcraft engine air intake. A reduced-order model based on proper orthogonal decomposition and a general regression neural network was employed to build the meta model, which covered the entire envelope of icing conditions. A compressible Navier-Stokes-Fourier computational fluid dynamics code was used to simulate the three-dimensional airflow around the rotorcraft engine air intake. High-fidelity droplet trajectory and ice accretion codes were also used to calculate the collection efficiencies and ice accretions on the anti-icing surface of the engine air intake in the heat-on mode. By considering airfoil and rotorcraft engine air intake cases, a feasibility study was then conducted to assess the meta model, using the leave-one-out cross validation method. The module was updated using a self-organizing map that contained k-mean clustering for the new samples in the parametric space. Lastly, the performance of the electrothermal anti-icing system was evaluated to demonstrate the practical use of the meta model. The distributions of ice thickness and icing parameters on the anti-icing surfaces can be used as guidelines for determining the required level of heater power and the size of heat pads.

Characteristics of icing without icicle on insulators under natural conditions

Icing on insulators seriously threatens the safe and stable operation of transmission lines. Most of the existing research has focused on the flashover characteristics of ice-covered insulators, lacking attention to the icing process on insulators. In order to reveal the mechanism of insulator icing, and lay the foundation for further establishment of insulator ice flashover model, this paper studies the characteristics of insulator icing without icicle. The characteristics of icing processes including the collision and freezing of water droplets, the generation and flowing of water film are analysed. On this basis, a three-dimensional numerical calculation model of insulator icing without icicle is established by using boundary element method, and the expressions of the local icing weight and thickness on the insulator surface are derived through the droplet local collision efficiency and freezing efficiency. Moreover, the time-varying characteristics of icing parameters are simulated. And the related icing tests are conducted on two kinds of insulators with different structures at Xuefeng Mountain. The results show that the distribution of collided water droplets and water film on the insulator surface will change with the increasing ice weight. Under natural conditions, compared with the aerodynamic insulator LDQ-100, the insulator LXY-120 with a smaller skirt diameter and a larger inclination angle can have a faster icing rate. However, at the insulator edge, the insulator LDQ-100 with a thinner shed has a greater icing rate of thickness. Compared with the test results, the simulation error of the model in this paper is within 15%.

Assessing the Potential of Enhanced Resolution Gridded Passive Microwave Brightness Temperatures for Retrieval of Sea Ice Parameters

A new enhanced resolution gridded passive microwave brightness temperature (TB) product is used to estimate sea ice concentration and motion. The effective resolution of the TBs is found to be roughly twice that of the standard 25 km resolution, though the gridded resolution of the distributed product is higher. Enhanced resolution sea ice concentrations from the Bootstrap algorithm show more detail in the sea ice, including relatively small open water regions within the ice pack. Sea ice motion estimates from the enhanced resolution TBs using a maximum cross-correlation method show a smoother motion circulation pattern; in comparison to buoys, RMS errors are 15–20% lower than motion estimates from the standard resolution fields and the magnitude of the bias is smaller as well. The enhanced resolution product includes other potentially beneficial characteristics, including twice-daily grids based on local time of day and a complete timeseries of data from nearly all multi-channel passive microwave radiometers since 1978. These enhanced resolution TBs are potential new source for long-term records of sea ice concentration, motion, age, melt, as well as salinity and ocean-atmosphere fluxes.