Long-Term Ice Conditions in Yingkou, a Coastal Region Northeast of the Bohai Sea, between 1951/1952 and 2017/2018: Modeling and Observations

Bohai Sea ice creates obstacles for maritime navigation and offshore activities. A better understanding of ice conditions is valuable for sea-ice management. The evolution of 67 years of seasonal ice thickness in a coastal region (Yingkou) in the Northeast Bohai Sea was simulated by using a snow/ice thermodynamic model, using local weather-station data. The model was first validated by using seasonal ice observations from field campaigns and a coastal radar (the season of 2017/2018). The model simulated seasonal ice evolution well, particularly ice growth. We found that the winter seasonal mean air temperature in Yingkou increased by 0.33 °C/decade slightly higher than air temperature increase (0.27 °C/decade) around Bohai Sea. The decreasing wind-speed trend (0.05 m/s perdecade) was a lot weaker than that averaged (0.3 m/s per decade) between the early 1970s and 2010s around the entire Bohai Sea. The multi-decadal ice-mass balance revealed decreasing trends of the maximum and average ice thickness of 2.6 and 0.8 cm/decade, respectively. The length of the ice season was shortened by 3.7 days/decade, and ice breakup dates were advanced by 2.3 days/decade. All trends were statistically significant. The modeled seasonal maximum ice thickness is highly correlated (0.83, p < 0.001) with the Bohai Sea Ice Index (BoSI) used to quantify the severity of the Bohai Sea ice condition. The freezing-up date, however, showed a large interannual variation without a clear trend. The simulations indicated that Bohai ice thickness has grown continuously thinner since 1951/1952. The time to reach 0.15 m level ice was delayed from 3 January to 21 January, and the ending time advanced from 6 March to 19 February. There was a significant weakening of ice conditions in the 1990s, followed by some recovery in 2000s. The relationship between large-scale climate indices and ice condition suggested that the AO and NAO are strongly correlated with interannual changes in sea-ice thickness in the Yingkou region.

Economics and politics of “old confrontation” in the New Arctic

The modern Arctic is becoming the strategic space and area of competition of many powers, the arena of political confrontations between Arctic and non-Arctic states. Arctic research has moved from the sphere of science to the sphere of geopolitics and geoeconomics and is of strategic importance in the system of national security. Climatic fluctuations in the Arctic have increased the availability of hydrocarbon, biological and other resources, and improved ice conditions in the water area of the Northern Sea Route. The study analyzes the Arctic policy of Western European and North American countries in the conditions of the “New Arctic”. An overview of strategic documents on ensuring the spatial development.

A review of level ice and brash ice growth models

Brash ice forms in harbours and ship channels from frequent ship passages and the resulting freezing–breaking cycles create a unique ice formation. The brash ice accumulation over the winter season is a result of meteorological, thermodynamical and mechanical processes. A reliable brash ice growth model is an important asset when determining navigation routes through ice conditions and when establishing port ice management solutions. This review aims to describe the brash ice development and its modelling as well as the key parameters that influence the brash ice growth and its estimation. This paper summarises the brash ice growth models and the fundamental theories of level ice growth upon which these models are based, and outlines the main knowledge gaps. The results highlight the importance of porosity and piece size distribution and their effect on the consolidation process. The inclusion of the brash ice lateral movement and the side ridge formation would improve the accuracy of forecast models. Furthermore, the findings of the study identify the effect of omitting meteorological parameters such as snow and radiation, from the brash ice growth models. Their contribution to the level ice thickness suggests a significant influence on the brash ice consolidation process.

Comparison of modern and fossil diatom assemblages and their implication on sea-ice conditions in coastal Antarctic region

Antarctic Coastal regions are thought to be characterized by high productivity usually dominated by diatoms. Considering their prime importance in global carbon biological pump, diatom distribution and abundance studies are sparse especially in coastal regions of Antarctica. Biogenic silica is considered to be severely affected by dissolution in the undersaturated ocean water, therefore, combined study of diatom assemblages from water column and those found in the sediments is important. Therefore, we conducted a combined study of sediment diatoms along with surface water diatoms collected from Coastal Antarctica. When the modern assemblages are compared to the fossil record, it is clear the most of the important diatoms from the summer assemblages are not preserved in the underlying sediments. The studies reveal that only F. kerguelensis is common abundant species in both water and sediment which suggests that coastal Antarctic region could be having more open ocean influence. In contrast, the presence of sea ice related diatom species from surface sediment indicate for expansion of sea ice or ice edge adjacent to the water column, however such species were not found in the overlying water samples which could be due to less sea-ice extent.

Ship operation in brash ice: results of investigations

The paper gives a review of the studies concerned with operation of vessels in brash ice. Recently, the ice conditions have received an ever increasing attention of the researchers related to the fact that shipping in the Arctic regions and freezing seas, as well as in inland waterways has been scaled up. One of the important fields of brash ice studies is specifics of sailing under these conditions and primarily determination of the ship ice resistance. The paper shows that theoretical methods combined with physical modeling in ice basins are used for determination of the ship ice resistance under brash ice conditions. The paper traces the evolution of theoretical models utilized for calculations. It is mentioned that the models are mainly based on loose material mechanics. A rapidly developing computer modeling of ship motion in brash ice based on discrete element method is considered. Physical modeling techniques used for modeling brash ice in ice basin are described, and challenges of experimental investigations are discussed. It is pointed out that experimental studies in ice basin can provide valuable data not only about ship ice resistance but also about the mechanisms giving rise to ice channels filled with brash ice. The paper describes the methods for studying operation of ship propellers in brash ice conditions. It is concluded that further research into brash ice is needed.

Subglacial bedform sensitivity to bed characteristics across the deglaciated Northern Hemisphere

Streamlined subglacial bedforms observed in deglaciated landscapes provide the opportunity to assess the sensitivity of ice dynamics to bed characteristics across broader spatiotemporal scales than is possible for contemporary glacial systems. While many studies of streamlined subglacial bedforms rely on manual mapping and qualitative (i.e., visual) assessment, we semi-automatically identify 11,628 erosional and depositional bedforms, created during and following the Last Glacial Maximum, across nine geologic and topographically diverse deglaciated sites in the Northern Hemisphere. Using this large dataset of landforms and associated morphometrics, we empirically test the importance of subglacial terrain on bedform morphology and ice-flow behavior. A minimum bedform length-width ratio threshold systematically provides a constraint on landform elongation during genesis and minimum morphometrics needed to resolve such bedforms in remote sensing data. Distribution ranges of bedform elongations are remarkably similar across all sites regardless of bed characteristics. These similarities in bedform metrics regardless of bed properties indicate all bed types may support streaming ice conditions. Regionally-constrained topography and easily erodible beds host the most elongate bedforms yet the widest range in bedform elongation and surface relief. This suggests higher ice-flow velocities and continuity of flow paths despite spatially heterogeneous landform-generating processes. In contrast, regions with unconstrained topography and lithified sedimentary beds contain high conformity in bedform density, relief, and elongation, indicating more spatially homogeneous interactions at the ice-bed interface and consistency in ice-flow velocity. Regardless of whether bedforms are erosional or depositional products, we ultimately find a relatively higher sensitivity of bedform elongation (i.e., ice streaming speed) to regional topography while bedform density is more sensitive to bed lithology. The findings presented here should be extrapolated to interpret processes of subglacial erosion and deposition, ice-bed interactions, and streaming ice flow within contemporary glacial systems.

Of a titan, winds and power: Transnational development of the icebreaker, 1890-1954

Icebreakers have traditionally been seen as symbols of technological nationalism. While ship science for open-water vessels developed during the late nineteenth and early twentieth centuries, understanding of how to cope with polar and subarctic ice conditions lagged behind. This led state organizations in charge of icebreaking services to minimize risks in the development of new vessels by encouraging transnational expert cooperation. This article argues that such interactions were critical to the evolution of the modern icebreaker. We examine the development of three icebreakers in different countries in successive decades, and the critical technologies with which they are associated: the Ymer from Sweden and diesel–electric propulsion (1933); the American ‘Wind’ class and power-hull proportion (1942–1946); and the Voima from Finland and twin bow propellers (1956). We reconstruct the flow of information to explain the rationale for transnational cooperation in maritime technology development. The concept of ‘technology carriers’ is deployed in the analysis to enhance understanding of the role of international cooperation in polar and winter seafaring.