Polar Navigation Research Articles

Exploring the Use of Fengyun-3 Meteorological Satellite for Monitoring Sea Ice to Provide Services for Polar Navigation

This paper explores the feasibility and effectiveness of using the Fengyun-3 meteorological satellite to monitor sea ice, providing services for ships navigating in polar regions. Firstly, it analyzes the impact of Arctic sea ice changes on ship navigation and the importance of sea ice monitoring in route planning. Next, it provides a detailed introduction to the data sources and processing methods of the Fengyun-3 satellite, including radiometric calibration, geometric correction, image registration, and cropping. Subsequently, it discusses the characteristics of sea ice in the visible spectrum and successfully extracts sea ice information using MERSI-II data with land, cloud, and seawater masking techniques. The study indicates that the comprehensive use of multi-spectral data and other observation methods can significantly enhance sea ice monitoring capabilities. In the future, integrating more advanced technologies is expected to achieve refined identification and short-term prediction of sea ice movement, thereby providing more scientific and efficient support for ships navigating in polar regions, enhancing navigation safety and efficiency, and offering a scientific basis for the development of Arctic shipping routes.

Effect of Low Temperature on the Fatigue Crack Propagation Behavior of Underwater Manned Vehicle Rudder Materials in Arctic Environments.

During polar navigation, adverse environmental conditions like cold temperatures, fatigue, and corrosion can affect surface and underwater manned vehicles (UMVs). Understanding the fatigue fracture growth behavior of polar ship steel is crucial for ensuring safety. This study investigates the mechanical properties and fatigue fracture propagation of steel used in underwater vehicle rudders under various low-temperature conditions through experimental research. It compares and analyzes the static mechanical characteristics, fatigue crack growth rate, and fracture morphology of underwater manned vehicle rudder steels at different low temperatures. Findings show enhancements in yield strength, tensile strength, elastic modulus, and fatigue crack propagation life of steel 925A, steel 20#, and their welded parts under low-temperature conditions. The tensile strength of 925A steel, 20# steel, and their welded parts increases by 6.87%, 14.61%, and 12.55%, respectively, as the temperature decreases from 20 to -60 °C. The yield strength also increases by 14.17%, 29.09%, and 15.76%, respectively. Fatigue crack propagation rate experiments were conducted under different constant low-temperature conditions. This study offers direction for future modeling and experimental testing.

Dynamic Projection Method of Electronic Navigational Charts for Polar Navigation

Electronic navigational charts (ENCs) are geospatial databases compiled in strict accordance with the technical specifications of the International Hydrographic Organization (IHO). Electronic Chart Display and Information System (ECDIS) is a Geographic Information System (GIS) operated by ENCs for real-time navigation at sea, which is one of the key technologies for intelligent ships to realize autonomous navigation, intelligent decision-making, and other functions. Facing the urgent demand for high-precision and real-time nautical chart products for polar navigation under the new situation, the projection of ENCs for polar navigation is systematically analyzed in this paper. Based on the theory of complex functions, we derive direct transformations of Mercator projection, polar Gauss-Krüger projection, and polar stereographic projection. A rational set of dynamic projection options oriented towards polar navigation is proposed with reference to existing specifications for the compilation of the ENCs. From the perspective of nautical users, rather than the GIS expert or professional cartographer, an ENCs visualization idea based on multithread-double buffering is integrated into Polar Region Electronic Navigational Charts software, which effectively solves the problem of large projection distortion in polar navigation applications. Taking the CGCS2000 reference ellipsoid as an example, the numerical analysis shows that the length distortion of the Mercator projection is less than 10% in the region up to 74°, but it is more than 80% at very high latitudes. The maximum distortion of the polar Gauss-Krüger projection does not exceed 10%. The degree of distortion of the polar stereographic projection is less than 1% above 79°. In addition, the computational errors of the direct conversion formulas do not exceed 10−9 m throughout the Arctic range. From the point of view of the computational efficiency of the direct conversion model, it takes no more than 0.1 s to compute nearly 8 million points at 1′×1′ resolution, which fully meets the demand for real-time nautical chart products under information technology conditions.

Sea ice detection network for icebreakers in polar environments with attention-based deeplabv3+ architecture

Shipborne sea ice detection aboard icebreakers plays a paramount role in polar navigation. The continuous evolution of deep learning semantic segmentation networks has promoted the advancement of sea ice detection tasks. At this stage, there are relatively few studies on shipboard sea ice detection, and the accuracy of polar sea ice detection will be reduced due to problems such as blurred sea fog and indistinct boundaries. In this study, a shipboard sea ice detection dataset is constructed, and a sea ice detection method that combines multi-branch attention feature alignment and multi-scale feature extraction is proposed. The heterogeneous receptive field enhancement atrous spatial convolution pooling pyramid module is designed, and the feature alignment module based on the attention mechanism is constructed, which strengthens the model’s extraction of sea ice features and elevates representation performance. Experimental results underscore the heightened precision of our approach in sea ice detection, to some extent alleviating the issue of missed detections in new ice. It constitutes a positive contribution towards advancing shipborne sea ice detection in polar environments.

Numerical simulation of the maneuvering performance of ships in broken ice area

Maneuverability is a critical aspect of ship navigation performance, particularly during polar navigation, where the presence of ice significantly affects maneuverability compared to open water navigation. By coupling the non-smooth discrete element method (NDEM) with the Maneuvering Modeling Group (MMG) model, this paper proposes a numerical model to simulate the maneuvering motion of full-scale ships in broken ice regions. In the proposed model, the ship-ice interaction was solved through NDEM, while the 3-DOF MMG model was utilized to simulate the autonomous navigation movement of ships. Based on the relationship between ship turning radius and ship speed, the critical relationship between ice moment and ice resistance is derived in this paper, which can be used to verify the rationality of simulation results of maneuvering motion. In addition, the effects of ice concentration, size, thickness, and ship speed and rudder angle on the ship's maneuvering trajectory and steering flexibility are analyzed by simulating turning motion and Zig-Zag maneuvers. This provides an effective numerical model to simulate the maneuvering motion of a ship in a broken ice area with low-medium ice concentration.

Dynamic Response Analysis of Submarines Based on FEM-ALE Coupling Method in Floating Ice Conditions

To address global challenges, research on the safety of polar navigation is indispensable. However, most of studies focus on traditional surface vessels, with few research studies on submarine. The dynamic response of submarine during surface navigation in floating ice channels under special conditions is studied in this work. Firstly, a model of the submarine incorporating an intact internal frame was established. Subsequently, the FEM-ALE coupled method was employed to simulate the structure-ice interaction, and the obtained results was verified by the Colbourne method. Then, the parametric study (navigation speed, ice thickness, and floating ice size) were analyzed from the perspectives of ice resistance, stress and plastic strain. Finally, an empirical equation suitable for the interaction between submarine and floating ice during surface navigation is improved based on the Colbourne method.

Numerical analysis method of ship-ice collision-induced vibration of the polar transport vessel based on the full coupling of ship-ice-water-air

As the Arctic Channel continues to be developed, collisions between polar navigation vessels and sea ice are inevitable, which will directly affect structural safety and vibration comfort. However, the numerical analysis method of ship–ice collision-induced vibration is not perfect, and the effect of fluid coupling is not typically considered. In this paper, a simplified numerical analysis method for ship–ice collision-induced vibration is proposed, in which a reliable ice load is obtained by first performing ship–ice–water–air coupled collision calculations, followed by ship–ice–water coupled vibration calculations to obtain the vibration response of the structure. In addition, this paper investigates the full coupling method and the modeling ranges and meshing sizes involved in the analysis ship–ice collision-induced vibration, and the computational efficiencies of the traditional ALE algorithm and S-ALE algorithm are compared. The results indicate that the simplified simulation analysis method and gradient meshing model improve the calculation accuracy and efficiency in ship-ice collision and vibration response analysis. Moreover, the modeling range of the water and air models cannot be less than 6 times the ship width, 2 times the ship length, and 1 times the ship depth, and the S-ALE algorithm saves 47.86% time compared to the ALE algorithm. The research results in this paper can provide a reference for the numerical simulation of ship–ice collision-induced vibration.

Simulation Study on the Factors Affecting the Solidification of Liquid Droplets with Different Salinity on Cold Surfaces

Salt spray splashing on the structural surfaces of ships is a common difficulty in polar navigation. In this paper, experiments are designed to study the variation in the growth peak of pure water droplets on the surface of a hydrophobic coating with a contact angle of 90°, and the numerical simulation method is verified according to the experiment. The variation in the growth peak calculated by the numerical simulation is consistent with the experiment, and the calculation error of the freezing time obtained by numerical simulation is less than 10% of that of the experiment. The freezing processes of droplets with salinity levels of 0, 10, 20, 30, 40, and 10 μL on the surfaces of the hydrophilic, hydrophobic, and super hydrophobic plates are studied. The freezing time of the droplets is calculated, along with the effects of the wall temperature, surface contact angle, and salinity on the freezing time and freezing process of the droplets. The results show that the freezing time increased dramatically with increasing salinity. The influence of the contact angle and substrate temperature on the freezing process was also concentrated. All these results contribute to a better understanding of the icing mechanism on marine surfaces.

Ice load prediction of a podded propulsor under the dynamic azimuthing condition

In the process of cutting an ice layer by dynamic azimuthing of a podded propulsor, the unsteady and high pulsation characteristics of the ice load may compromise the safety and structural strength of podded propulsors. In this study, the failure criterion of simulated materials for the ice-breaking problem and the ice load calculation method were derived based on the peridynamics and the idea of panel division. The contact judgment method between the propeller and ice under the dynamic azimuthing condition of the podded propulsor was proposed. A numerical calculation model of the milling action of the ice–podded propulsor was established, and a numerical simulation of the ice–propeller milling process under the dynamic azimuthing conditions of the podded propulsor was realized. Moreover, numerical simulations under different ice layer moving velocities, propeller rotational speeds, podded propulsor azimuthing rates, and azimuth angles were carried out, and the ice layer breaking phenomenon and the variation characteristics of the propeller ice load under the dynamic azimuthing condition of the podded propulsor were obtained. The research results can guide technical support for the load evaluation, structural safety analysis, mechanism research of load components, and the selection of polar navigation steering strategies for ice-class podded propulsors.

A Measurement System to Monitor Propulsion Performance and Ice-Induced Shaftline Dynamic Response of Icebreakers

Polar navigation entails challenges that affect the continuation of ship operations in severe ice conditions. Due to ice-propeller interaction, propulsion shafting segments are often at a high risk of failure. Efficient methods for shaft line design are hence needed to ensure the safety of ice-going vessels and propulsion reliability. To this end, full-scale measurements have proven essential to support the development of ship-design tools and updated safety regulations for ice-going vessels. This paper presents a unique integrated measurement system that employs measuring equipment to monitor Polar-Class vessel performance and shaft line dynamics during ice navigation. The system was installed on board the Canadian Coast Guard (CCG) icebreaker Henry Larsen. This experimental concept aims to monitor the shaft’s torque and thrust fluctuations during ice navigation to obtain information about the ship’s propulsion efficiency. In the paper, we describe the arrangement of the measurement system and the components it features. Finally, we present preliminary datasets acquired during two icebreaking expeditions. This work is framed into a broader research project, which includes the long-term objective to determine a correlation between sea ice conditions and the dynamic response of shaft lines.

Scenario-based optimization design of icebreaking bow for polar navigation

Global warming and ice extent reduction in Arctic makes commercial shipping through Arctic waters be promising in the near future. The fuel consumption and emission from ships on the Arctic shipping routes, which mainly depends on the ship resistance, is key factor to determine if it is more cost-effective comparing to traditional shipping route. The shipping route in Arctic water include open water and ice-covered water areas. The polar ships traveling through Arctic water need to have ice-strengthened hull to have ice-breaking capability to proceed safely in ice-covered water. Usually the bow hull form with good ice-breaking capability have high resistance in open water, while the bow form with good open-water efficiency (such as bulbous bow) may not have ice-breaking capability. This paper is to develop a methodology for optimized hull form design so that the minimum overall resistance in open-water and ice-covered water can be achieved, while maintaining desired level of ice-breaking capability for considered shipping route with expected ice conditions. The methodology proposed in this paper is based on the ship's desired route with historic ice data to define its typical operation profile. For the test example of this methodology, based on the desired route, the historic ice data are extracted from public available data source to determine the sections of open-water and ice-covered water, as well as the ice-thickness distribution along the route. The ship's resistance in open-water is calculated based on Rankine source method, while the ice resistance is calculated by Lindqvist formula. The overall resistance is weight-averaged based on the route's sections of open-water and ice-covered water. The ice-breaking capability is measured by the ice loads giving by the IACS Polar UR, which serves as the constraint during the optimization process. The parametric model is established for the optimization process. With an ice-breaking bow base design, the optimized bow hull form is achieved on the specified shipping route with historic ice condition. The result shows that the overall resistance is reduced by 5.42% while maintaining enough ice-breaking capability for the considered sample ship. Discrete Element Method is used to verify the optimized hull form's ice-breaking performance compatible with original hull form. It is shown that the methodology developed in this paper can be generally applied to polar ship hull form design for different shipping route and ice conditions.

Ship resistance when operating in floating ice floes: Derivation, validation, and application of an empirical equation

With the effects of global warming, the Arctic is presenting a new environment where numerous ice floes are floating on the open sea surface. Whilst this has improved Arctic shipping navigability in an unprecedented way, the interaction of such floes with ships is yet to be understood to aid the designing of ships and route planning for this region. To further explore this topic, the present work develops a procedure to derive an empirical equation that can predict the effects of such floes on ship resistance. Based on a validated computational approach, extensive data are extracted from simulations of three different ships with varying operational and environmental conditions. The ice-floe resistance is shown to strongly correlate with ship beam, ship buttock angle, ship waterline angle, ship speed, ice concentration, ice thickness and floe diameter, and the regression powers of each of the parameters on resistance are ascertained. This leads to a generic empirical equation that can swiftly predict ice-floe resistance for a given ship in a given condition. Subsequently, demonstrations are given on the incorporation of the derived equation into a set of real-time Arctic ship performance model and voyage planning tool, which can predict a ship's fuel consumption in ice-infested seas and dynamically suggest a route with the least safety concern and fuel consumption. Moreover, the equation is validated by providing ice resistance prediction for experimental and full-scale conditions from multiple sources, showing high accuracy. In conclusion, the empirical equation is shown to give valid and rapid estimates for ice-floe resistance, providing valuable insights into ship designs for the region, as well as facilitating practical applications for polar navigation.

Arctic sea ice cover data from spaceborne synthetic aperture radar by deep learning

Abstract. Widely used sea ice concentration and sea ice cover in polar regions are derived mainly from spaceborne microwave radiometer and scatterometer data, and the typical spatial resolution of these products ranges from several to dozens of kilometers. Due to dramatic changes in polar sea ice, high-resolution sea ice cover data are drawing increasing attention for polar navigation, environmental research, and offshore operations. In this paper, we focused on developing an approach for deriving a high-resolution sea ice cover product for the Arctic using Sentinel-1 (S1) dual-polarization (horizontal-horizontal, HH, and horizontal-vertical, HV) data in extra wide swath (EW) mode. The approach for discriminating sea ice from open water by synthetic aperture radar (SAR) data is based on a modified U-Net architecture, a deep learning network. By employing an integrated stacking model to combine multiple U-Net classifiers with diverse specializations, sea ice segmentation is achieved with superior accuracy over any individual classifier. We applied the proposed approach to over 28 000 S1 EW images acquired in 2019 to obtain sea ice cover products in a high spatial resolution of 400 m. The validation by 96 cases of visual interpretation results shows an overall accuracy of 96.10 %. The S1-derived sea ice cover was converted to concentration and then compared with Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentration data, showing an average absolute difference of 5.55 % with seasonal fluctuations. A direct comparison with Interactive Multisensor Snow and Ice Mapping System (IMS) daily sea ice cover data achieves an average accuracy of 93.98 %. These results show that the developed S1-derived sea ice cover results are comparable to the AMSR and IMS data in terms of overall accuracy but superior to these data in presenting detailed sea ice cover information, particularly in the marginal ice zone (MIZ). Data are available at https://doi.org/10.11922/sciencedb.00273 (Wang and Li, 2020).

Summary of the Test Methods for Icing Strength of Freshwater and Seawater

Polar navigation ships, offshore platforms, and amphibious aircraft sometimes need to work in low temperature environments, which will inevitably form varying degrees of icing on the surface of structures such as cabin doors. In order to ensure their normal working conditions, it is advisable to choose reasonable anti-icing and deicing methods to prevent icing or effectively remove icing. Therefore, it is necessary to study the mechanical properties of ice to provide a reference for the selection of anti-deicing methods. This article summarizes the common methods for measuring the shear strength and tensile strength of ice, which can provide some guidance for the freezing strength test of fresh water and sea water.

Research on UE4 - based Visualization Simulation of Underwater Vehicle Polar Region Sailing

With the continuous exploration of polar sea areas, the reliability and safety of polar navigation have become the top priority. Due to various influencing factors in the polar region, including sea ice, ocean currents, geomagnetism, gravity, etc., navigation equipment in the polar region cannot achieve the performance of the mid-low latitude region. Because of the limitation of the actual ship entering the polar region, the performance of navigation system in polar region cannot be fully verified. It is difficult to verify the performance of equipment on a real ship. In order to reduce the cost of the experiment while ensuring the accuracy of the verification and making the simulation training system available at the same time. Based on UE4(Unreal Engine4) to design a virtual 3D visual simulation platform of underwater vehicle that is able to simulate the six-degree-of-freedom(6-dof) motion of the underwater vehicle and verify the performance of navigation equipment in polar region. Verify the virtual simulation platform is able to simulate the movement of underwater vehicle in the virtual polar sea and realize the operation training simulation of underwater vehicle.

Automated iceberg tracking with a machine learning approach applied to SAR imagery: A Weddell sea case study

Drifting icebergs represent a significant hazard for polar navigation and are able to impact the ocean environment around them. Freshwater flux and the associated cooling from melting icebergs can locally decrease salinity and temperature and thus affect ocean circulation, biological activity, sea ice, and –on larger spatial scales– the whole climate system. However, despite their potential impact, the large-scale operational monitoring of drifting icebergs in sea ice-covered regions is as of today typically restricted to giant icebergs, larger than 18.5 km in length. This is due to difficulties in accurately identifying and following the motion of much smaller features in the polar ocean from space. So far, tracking of smaller icebergs from satellite imagery thus has been limited to open-ocean regions not covered by sea ice. In this study, a novel automated iceberg tracking method, based on a machine learning-approach for automatic iceberg detection, is presented. To demonstrate the applicability of the method, a case study was performed for the Weddell Sea region, Antarctica, using 1213 Advanced Synthetic Aperture Radar (ASAR) satellite images acquired between 2002 and 2011. Overall, a subset of 414 icebergs (3134 re-detections in total) with surface areas between 3.4 km2 and 3612 km2 were investigated with respect to their prevalent drift patterns, size variability, and average disintegration. The majority of the tracked icebergs drifted between 1.3 km and 2679.2 km westward around the Antarctic continent, following the Antarctic Coastal Current (ACoC) and the Weddell Gyre, at an average drift speed of 3.6 ± 7.4 km day−1. The method also allowed us to estimate an average daily disintegration (i.e. iceberg area decrease) rate of ~0.13% (~37% year−1) for all icebergs. Using the sum of all detected individual surface area reductions, we estimate a total iceberg mass decrease of ~683 Gt year−1, which can be freshwater input and/or new ‘child’ icebergs calved from larger icebergs. The extension to an automated long-term tracking method for icebergs is challenging as the iceberg shape can vary significantly due to abrupt disintegration or calving of bergy bits. However, our machine learning approach extended by automatic shape-based tracking capabilities proved to be a reliable alternative for automatic detection and tracking of icebergs, even under the ambiguous SAR background signatures often found in the Southern Ocean. In particular, the method works in the challenging near-coastal environment where the presence of sea ice and coastal ocean dynamics such as surface waves usually pose major obstacles for other approaches.

Unified All-Earth Navigation Mechanization and Virtual Polar Region Technology

For a strap-down inertial navigation system (SINS), a traditional navigation frame switching mechanization can be used to solve the all-Earth navigation problem, however, this kind of method suffers from complex and discontinuous algorithms. On the basis of improving vertical channel damping technology, a complete and unified all-Earth navigation scheme arranged in the Earth-centered Earth-fixed (ECEF) frame is designed as an alternative for global applications, which results in a simpler continuous algorithm and lower computational complexity. We also propose a virtual polar region technology based on the grid attitude and velocity invariant method (G-AVIM), which can complete the polar navigation verification through the actual test data of nonpolar regions. In the reconstructed polar region trajectory, the vehicle attitude, velocity, and height information relative to the ground remain unchanged, so the real test environment can be completely reproduced in the polar region. Simulations and field test results verified the proposed methods.

Transverse SINS/DVL Integrated Polar Navigation Algorithm Based on Virtual Sphere Model

Due to the principle error caused by the Earth’s sphere model in transverse polar navigation, the ellipsoid model is usually used for transverse transformation. In order to avoid the complex transverse transformation of the ellipsoid model, a virtual sphere model, which can simplify the transformation of the ellipsoid model, is constructed in this paper. With the requirements of high accuracy and long-time navigation for AUV in the polar region, the integrated navigation scheme of SINS/DVL, which is based on the virtual sphere model, is proposed. The proposed method can improve the navigation accuracy and suppress the oscillation error. The error equations of transverse SINS are established based on the virtual sphere model. Then, the transverse SINS/DVL integrated navigation algorithm is derived according to the new error equations. The simulation results show that the navigation accuracy of the proposed method is equivalent with the traditional ellipsoid model method and is better than that of the traditional sphere model method. However, the complexity of the proposed method is simpler than the traditional ellipsoid model method. Moreover, it is verified that the navigation accuracy of SINS/DVL integrated navigation system based on the virtual sphere model meets the requirements of AUV.

Research on Polar-region Coarse Alignment Algorithm Based on Grid System

Due to the convergence of meridians in polar regions, the geography-based northern-azimuth mechanics arrangement has problems such as increase of error and computational overflow in polar navigation, and the traditional compass alignment scheme is unable to operate normally. In this paper, the problem in polar navigation is solved by using the mechanics arrangement scheme, and a simulated analysis has been carried out on the application of compass alignment in high latitudes through static data, which verifies that it is unable to operate normally at the pole. Then compass alignment has been replaced by anti-sloshing coarse alignment and a simulated verification has been conducted on its correctness. After that, the latitude increment method is used to convert the sports car data at low-latitude regions to high-latitude regions and carry out a semi-physical simulation, which further verifies the correctness of the grid inertial navigation and the coarse alignment method in anti-sloshing polar region.

Practice Study on Operation Evaluation and Limitation for Merchant Ships in Polar Water

All environmental hazards impact safety for polar ships, especially polar merchant ship with light ice-class. In order to provide a systematic guidance to deal with any situation during polar operation, International Maritime Organization (IMO) raised mandatory requirements of “Polar Water Operation Manual”(PWOM) in Polar Code. This paper focuses on how to determinate operational evaluation and limitation for the PWOM, which is an important measure to avoid polar ships exceeding operational capability. Features of polar navigation are summarized based on the former polar navigation experience, and typical risk model is set up to describe the process of operation evaluation. The operational limitation is analyzed to indicate the actual capability and limitation as the ship encounters unexpected incident in polar waters. In conclusion, the operation procedure is studied to give a detailed technical proposals for the whole polar operation, which is the main component of PWOM. The outcome may provide helpful to arctic shipping of merchant ships.