|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
Kovalev, Sergey M. (Arctic and Antarctic Research Institute) | Smirnov, Victor N. (Arctic and Antarctic Research Institute) | Borodkin, Vladimir A. (Arctic and Antarctic Research Institute) | Shushlebin, Aleksandr I. (Arctic and Antarctic Research Institute) | Kolabutin, Nikolay V. (Arctic and Antarctic Research Institute) | Kornishin, Konstantin Alexandrovich (Rosneft Oil Company) | Efimov, Yaroslav Olegovich (Arctic Research Centre) | Tarasov, Petr Alexandrovich (Arctic Research Centre) | Volodin, Dmitry Alexandrovich (IK Sibintek LLC)
In the spring period of 2013–2017, the Russian Arctic and Antarctic Research Institute, in cooperation with the Rosneft Oil Company and the Arctic Research Centre, organized four complex expeditions in the Kara and Laptev Seas to study the physical and mechanical properties of sea ice (Fig. 1). Obtained data shows that for level ice with an increase in thickness, its mean temperature, salinity, and density decrease, but mean values of local strength and strength of ice samples at uniaxial compression increase. Failure zones of different intensity developed after the indenter penetration are studied. A range of comparison coefficients for local strength and uniaxial compression strength is updated.
Complex expeditions in the Kara and Laptev Seas were conducted in a period of maximum ice thickness onboard the nuclear icebreaker “Yamal,” with an onboard MI-8 helicopter. The main task was to evaluate the sea ice’s main physical (temperature, salinity, density, texture) and mechanical properties. Ice structures of different age gradations were studied with both borehole indenters and sample coring. A comparison of strength at the uniaxial compression of cylindrical ice samples drilled parallel to the ice cover surface, with the ice strength in conditions of uniform compression (local strength), was performed.
Measurements of ice temperature, salinity, and density, together with texture description, were performed at ice stations on two or more points. Sample coring was made with the core barrel “Kovacs Enterprise” with an internal diameter of 141 mm. Cores for texture analysis were oriented to cardinal directions with a magnetic compass. Taking into account the proximity of coring points, the texture pattern and physical properties of ice were considered as relative to the same ice.
Mironov, Yevgeny U. (Arctic and Antarctic Research Institute (AARI)) | Guzenko, Roman B. (Arctic and Antarctic Research Institute (AARI)) | Porubaev, Viktor S. (Arctic and Antarctic Research Institute (AARI)) | Kharitonov, Victor V. (Arctic and Antarctic Research Institute (AARI)) | Khotchenkov, Stepan V. (Arctic and Antarctic Research Institute (AARI)) | Nesterov, Aleksandr V. (Arctic and Antarctic Research Institute (AARI)) | Kornishin, Konstantin A. (Rosneft Oil Company) | Efimov, Yaroslav O. (Arctic Research Centre)
The article presents the results of an analysis of the expedition data on morphometry and internal structure of stamukhas, investigated in spring 2017 in the southwestern part of the Laptev Sea. Using a thermal drilling method, researchers obtained average and extreme values of all measured parameters and made an approximation by theoretical distribution functions. Analysis of sonar and tachometric survey data shows the average values of stamukha volume/mass to be more than five times greater than the average values of ice ridge volume/mass. The maximum duration of the recorded stamukhas’ drift was thirty days.
Stamukhas are grounded hummocked ice features (WMO, 2014). They present typical forms of immobile ice in the shallow offshore area of the Arctic ice-covered seas. Stamukhas are located in the coastal areas of the ice-covered seas at depths of 20–25 m. One distinguishes both large, separate stamukhas and chains consisting of several stamukhas. Being natural anchors, stamukhas influence the stability of landfast ice and the structure of the ice drift field, since ice floes are destroyed or change drift direction when they come into collision with stamukhas.
In the winter-spring period, stamukhas floating in the shipping routes are high-risk sites for ships and icebreakers, especially when visibility is poor. At the time of significant surge and tidal fluctuations of sea level in spring-summer, stamukhas can possibly float up to the surface and start drifting. Having a larger mass than ice ridges, stamukhas can influence the offshore structures, which makes it necessary to take them into account when calculating the ice loads (Alekseev et al., 2001). In addition, in the wintertime, influenced by the tidal currents, stamukhas can move over insignificant distances, but gouging the seabed at the same time. These negative phenomena should be taken into account in the design and pipe-laying over the seabed of shallow water areas of the seas.
Ishibashi, Shojiro (Japan Agency for Marine-Earth Science and Technology) | Tanaka, Kiyotaka (Japan Agency for Marine-Earth Science and Technology) | Yoshida, Hiroshi (Japan Agency for Marine-Earth Science and Technology) | Shinbori, Takashi (KOWA Co., Ltd.) | Uemura, Takayuki (KOWA Co., Ltd.) | Takegaki, Masato (KOWA Co., Ltd.)
The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is now developing a new special platform that will be moved freely under the sea ice and measure various kinds of data continuously and automatically. It is an Intelligent Underwater Drone for Arctic Ice (IUDA). The IUDA is designed in order to visualize the sea ice shape and topography from the “backside” by using acoustic technologies and optical technologies, at the same time it will measure sea water components under the sea ice in detail using science sensors. Since it is difficult to communicate with the IUDA under the sea ice, it should control all actions and behaviors by its own autonomous function. Now the conceptual design and basic design of the IUDA have already been finished and building has been started a proto-type.
In order to understand the present and the future earth, it is very important to grasp the details about the Arctic Ocean. The Arctic Ocean is located at the northernmost of the Earth and is the base point of the Earth, which is the center of movement. It is also the starting point for various phenomena occurring on the earth. In order to grasp the global environment as accurately as possible and precisely forecast the future environment, it is necessary to elucidate the change of the Arctic Ocean and the phenomenon caused by the change. Moreover, under the sea ice of the Arctic Ocean, there is a lot of valuable information to further accelerate understanding whole the Arctic Ocean. However, it is true that the Arctic Ocean covered by the wide and thick sea ice is an extreme environment that refuses human approach. To approach the true and real Arctic Ocean, it is required to know deeply not only the upper side (on the sea ice) but also under the sea ice.
Xu, Ning (National Marine Environmental Monitoring Center) | Wan, Yanlin (Dalian University of Technology) | Zhao, Boqiang (Liaoning Hongyanhe Nuclear Power Co., Ltd.) | Xu, Peng (Liaoning Hongyanhe Nuclear Power Co., Ltd.) | Chen, Yuan (National Marine Environmental Monitoring Center) | Yuan, Shuai (National Marine Environmental Monitoring Center) | Shi, Wenqi (National Marine Environmental Monitoring Center) | Ma, Yuxian (National Marine Environmental Monitoring Center) | Sun, Jianqiao (Tianjin University)
Sea ice is the main risk source for cold water acquisition of coastal nuclear power plants at high latitudes. In the waters with better hydrodynamic conditions, crushed ice accumulation is the main cause for blocking cooling water intakes of nuclear power plants. Therefore, the risk of sea ice accumulation should be assessed for nuclear power plants. In the study, the risk assessment and case analysis of sea ice dynamic accumulation in front of nuclear power intakes were performed. Firstly, theoretical analysis and historical case analysis indicated that the main risk indicators of sea ice dynamic accumulation are ice thickness, concentration, velocity, size and duration. Secondly, the technical process of dynamic sea ice accumulation risk assessment of intake port based on simulation was established. The sea ice accumulation risk should be considered or not depending on sea ice environmental conditions. Finally, a coastal nuclear power plant in the Bohai Sea was selected as an example to verify the assessment model. With the dilated disk discrete element model, sea ice dynamic accumulation was simulated. The ice blockage degree in the water intake channel was selected as the indicator for risk grading. The thresholds of sea ice risk levels corresponding to different blocking levels of intake channel as well as corresponding design recurrence periods were calculated. The overall ice force caused by ice accumulation was also evaluated. The assessment method of dynamic sea ice accumulation risk proposed in this paper can be applied in the risk management of equipment involving the cold water intake function in ice-covered sea areas.
China’s first ice area nuclear power project, Liaoning Hongyanhe Nuclear Power Plant, has entered the commercial operation stage. A nuclear power plant consumes a large quantity of circulating cooling water during operation. The nuclear power project in the cold area of China is facing the safety risk of cold water intake, especially the risk that the sea ice may pose to water intakes. The experiences in the operation of nuclear power projects in ice regions in China are not enough and especially the anti-icing design standard of the cold water intake projects is not available. In addition, the mechanism of the impact of ice floes on the water intake of cold sources is not clear. Therefore, the economic industry and ecological environment in the northern seas of China are exposed to unknown risks caused by potential ice disasters of nuclear power projects. The operation state of the water intake directly affects the operation safety and reliability of the power plant and the problem of water intake blockage is one of its important safety problems. Ice floes in front of the water intake of a nuclear power plant is prone to be sucked into the water intake, thus blocking the water intake (Ding, 2000; Xu and Yue, 2009). Therefore, it is necessary to analyze the mechanism of floating ice accumulation in front of the water intake of a nuclear power plant and analyze the water intake safety for early warning.
Kovalev, Sergey M. (Arctic and Antarctic Research Institute) | Smirnov, Victor N. (Arctic and Antarctic Research Institute) | Borodkin, Vladimir A. (Arctic and Antarctic Research Institute) | Shushlebin, Aleksandr I. (Arctic and Antarctic Research Institute) | Kolabutin, Nikolay V. (Arctic and Antarctic Research Institute) | Kornishin, Konstantin A. (Rosneft Oil Company) | Efimov, Yaroslav O. (Arctic Research Centre) | Tarasov, Petr A. (Arctic Research Centre) | Volodin, Dmitry A. (IK "Sibintek" LLC)
In 2013-2017 Russian Arctic and Antarctic Research Institute in cooperation with Rosneft Oil Company and Arctic Research Centre organized four complex expeditions in the Kara and Laptev seas to study sea ice physical and mechanical properties (Fig. 1). Obtained data show that generally with increase of ice thickness its’ mean temperatures decrease, mean salinity and density for level ice decrease, but thickness mean local strength and strength of ice samples at uniaxial compression increase. Failure zones of different intensity developed after indenter penetration are studied. A range of comparison coefficient for local strength and uniaxial compression strength is updated.
Complex expeditions in the Kara and Laptev seas were conducted in the period of maximum ice thickness on the board of atomic icebreaker “Yamal” with an onboard MI-8 helicopter. The main task was evaluation of the sea ice main physical (temperature, salinity, density, texture) and mechanical properties. Ice structures of different age gradations were studied with both borehole indenter and sample coring. A comparison of strength at uniaxial compression of cylindrical ice samples drilled parallel to the ice cover surface with the ice strength in conditions of uniform compression (local strength) was performed.
Measurements of ice temperature, salinity, density together with texture description were performed at ice stations on two or more points. Sample coring was made with core barrel «Kovacs Enterprise» of 141 mm internal diameter. Cores for texture analysis were oriented to cardinal directions with a magnetic compass. Taking to account proximity of coring points the texture pattern and physical properties of ice were considered as relative to the same ice.
At all stations ice and snow thickness as well as ice over water surface exceeding, air temperature, temperature at snow/ice boundary were measured. Textural analysis was made based on a study of ice plates of 2-3 cm thickness. Digital pictures of all plates were taken with a camera that allowed to receive high quality photos with resolution sufficient for further processing.
Strength-temperature relationships are presented for four categories of ice: first-year ice (FYI), second-year ice (SYI), young multi-year ice (yMYI) and thick multi-year ice (TkMYI). The equations are based upon the borehole strengths (BHS) measured during 876 tests in 162 boreholes. The strength of every type of sea ice decreases with increasing ice temperature. FYI and SYI are governed by nearly identical BHS-temperature relations for overlapping temperatures in the range −10°C to 0°C, but it is also important to note that SYI can be expected to deteriorate about one month later than FYI. The BHS-temperature relations for yMYI and TkMYI are similar over the temperature range −9°C to −2°C. Factors other than ice temperature affect ice strength, so it is to be expected that equations based solely upon ice temperature cannot reproduce the BHS exactly. The BHS was overestimated for 56.8 to 69.4% of tests performed at individual test depths and 61.1 to 72% of the depth-averaged BHS for individual boreholes, depending upon ice category. Cold ice produces the lowest relative errors in strength, and warm porous ice the highest relative errors in strength.
Multi-year ice (MYI) and second-year ice (SYI) exert the highest loads on offshore structures (Frederking and Sudom, 2006; Sudom and Frederking, 2010). MYI and SYI are not the same, yet they are usually grouped together as ‘old ice’, which the WMO (1985) defines as sea ice that has survived at least one summers’ melt. Differentiating MYI and SYI has become more pressing since the International Maritime Organization’s (IMO) Polar Code came into effect in January 2017. Two of the three Polar Ship categories will be permitted to transit regions of FYI that may contain old ice inclusions if the ship has (a) an appropriate ice class and (b) an approved methodology for determining the ship’s operational limitations in ice. One such methodology, POLARIS, permits mariners to differentiate between SYI, ‘light’ MYI, and ‘heavy’ MYI when the ice thickness can be determined confidently (IMO, 2014). That approach may seem reasonable since the WMO’s graduated classification system is based upon ice thickness, but it may not be appropriate for old ice because thickness can be an unreliable indicator for gauging the severity of old ice (B. Gorman personal communication; Johnston, 2012). The question that this study seeks to address is “does classifying sea ice incorrectly carry serious consequences for shipping and offshore activities?”. To help answer that question, we investigate whether different types of sea ice have different strengths, for comparable temperatures. That said, the temporal aspect (i.e. time of year) is also important because ice takes time to reach a given temperature. The temporal aspect is not examined here since it is discussed in Johnston (2017).
The form drag on sea ice ridge plays an important role in ice-ocean momentum exchange and determines the drift of sea ice. This paper presents a study on the water drag force on ridge keels of sea ice through both physical and numerical simulations. Tests comprising of six slope angles (α) of ridge keel, five keel depths (h), and twelve flow velocities (u) have been conducted, and the physical modelling results agree well with the numerical simulations. The results reveal that the drag force on ridge keel increases with increasing α, h, and u. The impact of the size of the tank on ice-water drag force is discussed, and size-free results are obtained through numerical simulations. The form drag coefficient on ridge keel nearly has nothing to do with u and h, but obviously increases with α. A parameterization of the drag coefficient is proposed as C = 0.315×ln(α) − 0.616, which is potential to be applied to full scale sea ice in the polar regions
Climate warming is an important distinct trend of global climate. Global warming is amplified in Arctic and is called Arctic amplification (Screen and Francis, 2016). As the most important feature of polar regions, sea ice has an important influence on atmospheric circulation, ocean circulation and global climate. In recent years, the rapid changes in Arctic sea ice on northern hemisphere weather becomes more and more obvious, so the research on the change of Arctic sea ice is also becoming increasingly important (Stephenson and Pincus, 2017). Among the research methods on polar sea ice, numerical simulation is becoming one of the important means. Ice dynamics describes the interaction between flow and the sea ice, also between atmosphere and the sea ice, when the interaction between flow and sea ice, the drag coefficient is an important factor in determining the flow drag force, and the parameterization on the drag coefficient has been gradually developed (Tsamados et al., 2014).
The recurrent interactions between ocean waves and sea ice are a widespread feature of the polar regions, and their impact on sea-ice dynamics and morphology has been increasingly recognized as evidenced by the surge of research activity during the last two decades. The rapid decline of summer ice extent that has occurred in the Arctic Ocean over recent years has contributed to the renewed interest in this subject. Continuum models have recently gained popularity to describe wave propagation in various types of ice cover and across a wide range of length scales. In this paper, we propose a continuum wave-ice model where the floating sea ice is described as a homogeneous poroelastic material and the underlying ocean is viewed as a slightly compressible fluid. The exact dispersion relation for linear traveling wave solutions of this coupled system is established and compared to predictions from existing theories.
Wave-ice interaction is a two-way process. Ice scatters ocean waves and redistributes wave energy, in turn gravity waves stress and potentially fracture ice. In this paper, we focus on the phenomenon of ice-induced wave attenuation (Wadhams et al, 1988). A common place where waveice interactions play an important role is the marginal ice zone (MIZ), which is the outer edge of the ice cover, closest to the open ocean. It typically consists of ice floes, brash ice and open water.
Several linear models have been proposed to study wave-ice interactions and can generally be classified into two categories: solitary-floe models and continuum models (Squire, 2007; Kohout and Meylan, 2008). Of special interest here is the latter category. The mass-loading (ML) model is probably the most basic continuum formulation. It treats ice floes as a simple mass load on the ocean surface. The thin elastic plate model (hereafter referred to as FS) incorporates the elastic response of the ice layer into the formulation, with the ice layer being described as a Kirchhoff-Love plate (Fox and Squire, 1994). Alternatively, Keller (1998) proposed a two-layer formulation where a viscous fluid layer lies on top of an ideal fluid region. In this context, viscosity stems from the fact that the ice cover is viewed as a suspension of solid particles in water. Building upon Keller’s work, Wang and Shen (2010, now referred to as WS) included elasticity in the upper layer and described the ice layer as a homogeneous incompressible viscoelastic medium according to Voigt’s model. Their viscoelastic fluid model synthesizes the thin elastic plate and viscous layer models as limiting cases under suitable conditions. Recently, Mosig et al (2015) extended the FS model by introducing a complex Voigt shear modulus to account for viscous dissipation. This extended model is referred to as EFS in the following sections.
Smirnov, Victor N. (Arctic and Antarctic Research Institute) | Kovalev, Sergey M. (Arctic and Antarctic Research Institute) | Znamensky, Maxim S. (Arctic and Antarctic Research Institute) | Kolabutin, Nikolay V. (Arctic and Antarctic Research Institute) | Kornishin, Konstantin A. (Rosneft Oil Company) | Efimov, Yaroslav O. (Arctic Research Centre) | Pavlov, Vladimir A. (Rosneft Oil Company)
This paper describes dynamic processes in the sea ice observed during ice monitoring in the Kara and Laptev seas. Wave events are studied instrumentally under assumption that sea ice is an interaction indicator of the air-ice-water system. Wind waves and free swell waves from far storms in the open water are considered as background oscillations. Compression/ridging events and heterogeneity of ice drift generate periodic micro-shearings that can be registered in ice cover as mechanical horizontally polarized waves. Ice compression/fracture event can be predicted by analyses of ice micro-shearings. This shortterm method of ice compression and ridging forecast showed good results for processes in drifting and fast ice.
Forecasting of extreme ice events is based on ice cover monitoring and in particular its physical and mechanical changes and large-scale dynamic reactions. Oscillation and wave processes in the ice give a lot of important information for analysis. The most typical dynamic processes in sea ice are vertical and horizontal displacements. These ice movements and failures occur continuously and determine the ice cover structure. Extensive fractures, ridges of hummocks and open-water channels can originate from significant ice compression forces.
First big-scale experiments of ice cover monitoring were carried out by authors in the Kara sea during Rosneft Oil Company expedition “Kara-winter-2014”. Fluctuations of ice drift velocity and ice horizontal displacements were continuously registered during the tests by special measurement complex. It is shown how sea ice drift is accompanied by ice deformations during different ice events (compression, formation of cracks). Ice drift depends not only on local wind and on sea currents but also on wind in neighboring areas. Displacement velocity in consolidated compressed ice for measurements in a distance of 100 km reached 3 cm/s (Legenkov, 1988). Estimation of ice forces in the periods of intensive compression allows to obtain external forces and investigate their distribution along the ice drift trajectory. Due to the total mass and acceleration of ice, these forces of drifting ice interaction can reach hundreds of kilonewtons (Sheikin et al., 2006).
The IMO Polar Code requires operators to consider the hazards associated with the specific environment of operation in Polar waters. Various sources of climate and environmental data are publicly available to quantify environmental hazards. This study considers an example Ice Class IB ship, that is not intended to operate in low air temperature (as defined in the Polar Code), and not intended to operate in marine icing conditions. Considering these hazard limitations in concert with analysis of historical data, a theoretical operational envelope for the ship is established. The methodology presented in this paper can be expanded to include more hazards as appropriate. Proposals are provided on future enhancements.