Ice-covered Areas Research Articles

Linking PVA models into metamodels to explore impacts of declining sea ice on ice-dependent species in the Arctic: the ringed seal, bearded seal, polar bear complex

Arctic ecosystems are especially vulnerable to the impacts of climate change because of the limit to possible northward shifts for species dependent on land or continental shelf and because the rate of warming of the region has been 2-4 x the global average in recent decades. The decline in sea ice in the Arctic has both direct and indirect impacts on the species that live in association with ice, breeding on it, traveling over it, feeding on other ice-dependent species or avoiding competition with subarctic species that cannot exploit resources in ice-covered areas. Herein, we present a metamodel of a top-level predator, the polar bear (Ursus maritimus), and two of its key prey species, ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus), which are important in maintaining current polar bear densities and in turn are strongly influenced by bear predation. We used a metamodel that links Population Viability Analyses of the three species in order to examine how the impacts of declining spring land-fast sea ice on the fjords of Svalbard (Norway) and Frans Josef Land (Russia) can cascade through this predator-prey system. As the ice conditions that allow ringed seals to raise pups in snow-covered lairs on the frozen fjords diminish, or even disappear, ringed seal populations using the land-fast sea ice will collapse due to lack of successful recruitment. Consequently, the polar bear population, which relies heavily on hunting ringed seals in the land-fast sea ice to be able to raise their own offspring is also likely to decline. Our models suggest time-lags of decades, with the polar bear population not entering into decline until the lack of recruitment of ringed seals results in the depletion of breeding age ringed seals – starting in the third decade from the start point of the model and dropping below the initial population size only some decades later. Although lags between climate change and impacts on the ice-associated fauna are expected, the sea ice conditions have already changed dramatically in the northern Barents Sea region, including the Svalbard Archipelago, and the collapse of this Arctic species assemblage might already be underway.

Dynamic numerical simulation of ice-propeller milling based on GPU parallel computing

To integrate high-performance GPU parallel computing with the peridynamics method and enhance the computational efficiency of numerical simulations for ice-propeller milling, thus providing better data support for the design of propellers in ice-covered areas, a GPU-based parallel peridynamics computational approach was developed on CUDA in this study. The approach was built upon the bond-based peridynamics theory and CUDA programming framework, and its validity was confirmed using test cases involving an airfoil cutting ice and an ice ball impacting a rigid wall. A corresponding three-dimensional GPU parallel computational program was created for the ice-propeller milling process, and the computational code was optimized, resulting in a 24-fold increase in computational efficiency. Utilizing the high-performance computational code, the influence of sea ice elastic modulus and propeller pitch on the mechanical performance of the blades was investigated. The computational results revealed that the ice loads on the blades increased with rising elastic modulus and decreased with increasing pitch, and a larger pitch led to more sea ice being milled away.

Modelling snowpack on ice surfaces with the ORCHIDEE land surface model: application to the Greenland ice sheet

Abstract. Current climate warming is accelerating mass loss from glaciers and ice sheets. In Greenland, the rates of mass changes are now dominated by changes in surface mass balance (SMB) due to increased surface melting. To improve the future sea-level rise projections, it is therefore critical to have an accurate estimate of the SMB, which depends on the representation of the processes occurring within the snowpack. The Explicit Snow (ES) scheme implemented in the land surface model Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) has not yet been adapted to ice-covered areas. Here, we present the preliminary developments we made to apply the ES model to glaciers and ice sheets. Our analysis mainly concerns the model's ability to represent ablation-related processes. At the regional scale, our results are compared to the MAR regional atmospheric model outputs and to MODIS albedo retrievals. Using different albedo parameterizations, we performed offline ES simulations forced by the MAR model over the 2000–2019 period. Our results reveal a strong sensitivity of the modelled SMB components to the albedo parameterization. Results inferred with albedo parameters obtained using a manual tuning approach present very good agreement with the MAR outputs. Conversely, with the albedo parameterization used in the standard ORCHIDEE version, runoff and sublimation were underestimated. We also tested parameters found in a previous data assimilation experiment, calibrating the ablation processes using MODIS snow albedo. While these parameters greatly improve the modelled albedo over the entire ice sheet, they degrade the other model outputs compared to those obtained with the manually tuned approach. This is likely due to the model overfitting to the calibration albedo dataset without any constraint applied to the other processes controlling the state of the snowpack. This underlines the need to perform a “multi-objective” optimization using auxiliary observations related to internal snowpack processes. Although there is still room for further improvements, the developments reported in the present study constitute an important advance in assessing the Greenland SMB with possible extension to mountain glaciers or the Antarctic ice sheet.

Plastid marker variation reveals immigration history in Scandinavian Syntrichia norvegica and S. ruralis (Pottiaceae, Bryophyta)

ABSTRACT Introduction Based on previous analyses of Syntrichia norvegica and S. ruralis, the idea of panmictic populations in Scandinavia can be rejected, despite the high dispersal capacities of wind-dispersed spores. We tested, using comprehensive European datasets, whether intraspecific phylogeographical structure reflects glacial and post-glacial history. We expected different entities to indicate immigration from known Late Glacial Maximum refugial areas, and habitat differentiation. Methods Using plastid markers (atpB–rbcL and rpl16), we investigated 45 and 190 Scandinavian and 17 and 15 non-Scandinavian specimens of Syntrichia norvegica and S. ruralis, respectively. Key results We revealed four intraspecific entities in Syntrichia norvegica. Two were from the Scandinavian mountains and the Alps, and one from the Scandinavian mountains only. The fourth was widespread across the Scandinavian mountains, the northern lowlands, and the Baltic Sea islands Öland and Gotland. For S. ruralis, we recovered five entities, of which three were from both Scandinavia and the Alps. One of these occurred in strongly calcareous habitats in southern Scandinavia and the Alps and dominated on Öland and Gotland. One entity was widely distributed only in Scandinavia. One was restricted to the border between boreo-nemoral and southern-boreal Scandinavia. Conclusions The plastid haplotype distribution patterns suggest glacial survival of Syntrichia norvegica and S. ruralis in refugia south, east and possibly within ice-covered areas of Scandinavia. We hypothesise that one S. ruralis entity evolved adaptations to strongly calcareous habitats. The dominance or prevalence of specific haplotypes of both species on Öland and Gotland contributes to the unique biodiversity of these islands.

Enhanced Analysis of Ice Accretion on Rotating Blades of Horizontal-Axis Wind Turbines Using Advanced 3D Scanning Technology

This study investigated the meteorological conditions leading to ice formation on wind turbines in a coastal mountainous area. An enhanced ice formation similarity criterion was developed for the experimental design, utilizing a scaled-down model of a 1.5 MW horizontal-axis wind turbine in icing wind tunnel tests. Three-dimensional ice shapes on the rotating blades were obtained and scanned using advanced 3D laser measurement technology. Post-processing of the scanned data facilitated the construction of solid models of the ice-covered blades. This study analyzed the maximum ice thickness, ice-covered area, and dimensionless parameters such as the maximum dimensionless ice thickness and dimensionless ice-covered area along the blade. Under the experimental conditions, the maximum ice thickness reached 0.5102 m, and the ice-covered area extended up to 0.5549 m2. The dimensionless maximum ice thickness and dimensionless ice-covered area consistently increased along the blade direction. Our analysis of 3D ice shape characteristics and the ice volume under different test conditions demonstrated that wind speed and the liquid water content (LWC) are critical factors affecting ice formation on blade surfaces. For a constant tip speed ratio, higher wind speeds and a greater LWC resulted in increased ice volumes on the blade surfaces. Specifically, increasing the wind speed can augment the ice volume by up to 57.2%, while increasing the LWC can enhance the ice volume by up to 149.2% under the experimental conditions selected in this study.

Towards automatic identification of ship-ice contact using acceleration measurement

When a ship navigates in ice-covered areas, its hull experiences motion and vibration responses due to ship-ice contact. The magnitude of such responses can be represented well by acceleration, which is easy to measure onboard ice-going ships. The level of acceleration is determined by the environmental and operational conditions through excitation via the ship-ice contact. Conversely, it is possible to infer excitation and environmental conditions using acceleration measurements via appropriate methods. Accelerations associated with such responses can also affect the functionality of the onboard equipment and therefore, should be quantified. Nevertheless, studies on shipborne acceleration measurements in ice fields and their links to prevailing excitations and environmental conditions are rare. This study explores the feasibility of using shipborne acceleration measurements to infer the corresponding excitations (i.e., ship-ice contacts) as a first step towards the inference of ice conditions via acceleration measurements. An automatic identification method for ship-ice contact is proposed that can effectively separate ship-ice contact events from acceleration measurement signals. The acceleration signals are decomposed in the time-frequency map obtained through a short-time Fourier transformation (STFT). An improved detection transformer (DETR) model was used to automatically identify ship-ice contact events and achieved good accuracy in the validation set. This model was then applied to automatically identify ship-ice contacts using acceleration signals under various environmental and operational conditions. The frequency of the identified ship-ice contact reasonably reflects its dependence on prevailing environmental and operational conditions, which confirms the validity of the proposed methodology.

Numerical simulation of hydraulic characteristics and pollutant transport in the channels with different ice coverages

ABSTRACT In winter, rivers at high latitudes often freeze and an ice cover emerges at the free surface of the river. According to the coverage degree of the ice cover, rivers can be divided into free-flowing, partially frozen, and completely frozen. The presence of ice cover can greatly alter the hydraulic conditions of rivers, complicating the transport of pollutants in river channels. The distribution of pollutants in rivers with different ice coverages was simulated using the Detached Eddy Simulation (DES) model in this paper. The velocity distribution, the pollutant diffusion coefficient distribution, the turbulent kinetic energy distribution, and the vortex distribution with different ice coverages were analyzed. The velocity in the ice cover zone is at a lower rate than in the open flow zone. With the increase of the ice coverage, the turbulent kinetic energy of the ice cover area in partially frozen conditions gradually increases, which makes the water flow turbulence increase. The diffusion coefficient of pollutants in the ice cover area is greater than that in the open flow area, so pollutants disperse more quickly in the ice cover area. The turbulence energy and the diffusion coefficient have similar distribution characteristics beneath the ice cover. The presence of the ice cover promotes the movement of the vortex from the open flow area to the ice cover area, which may be the reason for the larger turbulence energy and the diffusion coefficient. The simulation results can provide a reference for ice disasters and water quality remediation.

Ice cover loss and debris cover evolution in the Afghanistan Hindu Kush Himalaya between 2000 and 2020

ABSTRACT Glaciers in Afghanistan are crucial elements for water resource and summer river flows. They are also threatened by rapid climate warming. This study presents an up-to-date assessment of ice cover loss for the entire country over two periods, 2000–2008 and 2008–2020, using newly developed remote sensing indices that include a more reliable determination of changing debris cover. The results suggest an estimated ice-covered area of 2,684 ± 101 km2 in 2020, that was 75 ± 0.7% clean ice and 25 ± 3.0 percent debris-covered ice. Total ice-covered area retreated by −0.15 ± 0.01 percent yr−1 between 2000 and 2008 and −0.43 ± 0.05 percent yr−1 between 2008 and 2020. Notably, 60 percent of ice cover loss (2000–2020) related to ice cover extents with a size ≤ 2.5 km2, comprising 60 percent of the total ice-covered area in 2000. Higher altitude accumulation zones also exhibited mass loss. However, there was also substantial spatial variation in these rates of loss based on geographical region, glacier size, and climate zones. In the north-eastern regions that are geographically close to or part of the north-west Karakoram ice cover was declining at a substantially lower rate, stable, or even increasing slightly, as compared with the northern and central regions of Afghanistan.

Sea ice and waves in the Sea of Okhotsk from 1989 to 2012

Coastlines along the Sea of Okhotsk in Hokkaido are the southernmost regions in the northern Pacific Ocean where sea ice reaches the coast. It has been demonstrated that global warming affects and decreases the ice cover area in the Sea of Okhotsk. This study thus aims to investigate the relationship between sea ice and waves in the Sea of Okhotsk by analyzing ice cover area, sea ice volume, significant wave height and significant wave period. Additionally, we made an attempt to clarify trends in ice cover area and sea ice volume from 1989 to 2012 using satellite images. Sea ice volumes in the northern part of the Sea of Okhotsk correlate with significant wave height and significant wave period. Furthermore, ice cover area and sea ice volume have decreased since 2001 or 2002, which may enhance wave action during winter.

Sea ice cover in the Copernicus Arctic Regional Reanalysis

Abstract. The Copernicus Arctic Regional Reanalysis (CARRA) is a novel regional high-resolution atmospheric reanalysis product that covers a considerable part of the European Arctic including substantial amounts of ice-covered areas. Sea ice in CARRA is modelled by means of a one-dimensional thermodynamic sea ice parameterisation scheme, which also explicitly resolves the evolution of the snow layer over sea ice. In the present study, we assess the representation of sea ice cover in CARRA and validate it against a wide set of satellite products and observations from ice mass balance buoys. We show that CARRA adequately represents general interannual trends towards thinner and warmer ice in the Arctic. Compared to ERA5, sea ice in CARRA shows a reduced warm bias in the ice surface temperature. The strongest improvement was observed for winter months over the central Arctic and the Greenland and Barents seas where a 4.91 °C median ice surface temperature error in ERA5 is reduced to 1.88 °C in CARRA on average. Over Baffin Bay, intercomparisons suggest the presence of a cold winter-time ice surface temperature bias in CARRA. No improvement over ERA5 was found in the ice surface albedo with spring-time errors in CARRA being up to 0.08 higher on average than those in ERA5 when computed against the CLARA-A2 satellite retrieval product. Summer-time ice surface albedos are comparable in CARRA and ERA5. Sea ice thickness and snow depth in CARRA adequately resolve the annual cycle of sea ice cover in the Arctic and bring added value compared to ERA5. However, limitations of CARRA indicate potential benefits of utilising more advanced approaches for representing sea ice cover in next-generation reanalyses.

“Environmental Dimension” of Article 234 of the United Nations Convention on the Law of the Sea and Russian Legislation on the Regulation of Navigation in the Waters of the Northern Sea Route

INTRODUCTION. Climate change in the Arctic, caused by global warming, as well as the political processes taking place in the world associated with increased pressure from the countries of the collective West on the Russian Federation, again raise in Western doctrine the question of the validity of the Russian Federation establishing a national regime for navigation in the waters of the Northern Sea Route in accordance with Article 234 of the 1982 UN Convention on the Law of the Sea. Doubts have been raised about our country’s compliance with the Convention’s requirement to maintain a balance between freedom of navigation and environmental protection. The purpose of this work is to analyze the validity of claims against the Russian Federation regarding its alleged abuse of the right to establish a national regime for navigation in the Arctic under the guise of environmental protection.MATERIALS AND METHODS. The problems raised in the work are structurally divided into three main groups. The first of them is related to the analysis of the characteristics of shipping in the Arctic under conditions of a changing climate, as well as the determination of the need to establish a special legal regime for navigation in polar waters. The second is devoted to the systematic interpretation of Article 234 of the UN Convention on the Law of the Sea, in its relationship with other norms of the Convention, identifying the criteria and restrictions established therein in relation to the rules of navigation adopted by the coastal state in ice-covered areas, as well as the legal content of the requirement of “due attention to navigation and protection and conservation of the marine environment.” The third part of the work is devoted to assessing the legislation of the Russian Federation on the regulation of navigation along the Northern Sea Route for its compliance with the requirements of Article 234 and maintaining the balance of freedom of navigation and protection of the marine environment in the Arctic.RESEARCH RESULTS. The legislation of the Russian Federation on the regulation of navigation in the waters of the Northern Sea Route fully meets the conditions and criteria established by Article 234 of the Convention, and is aimed at ensuring the functioning of a unified and centralized system for managing the safety of navigation in the particularly dangerous conditions of the Arctic, preventing accidents and environmental pollution environment. The restrictions established by Russian legislation are not discriminatory and are based on current and constantly updated scientific data.DISCUSSION AND CONCLUSIONS. Shipping in polar waters involves enormous risks to human life, valuable property and an extremely fragile and vulnerable environment. The effects of global warming are only exacerbating these risks, leading to increased ice instability and worsening climate problems. In this regard, in ice-covered areas, a centralized navigation management system is objectively necessary, and the establishment of special, uniform legal regulation to ensure the uninterrupted functioning of such a system. A systematic interpretation of Article 234 of the UN Convention on the Law of the Sea allows us to conclude that the establishment by a coastal state within its EEZ of non-discriminatory laws and regulations aimed at preventing, reducing and keeping under control pollution of the marine environment from ships is not a privilege, but a duty of the state based on its more general obligation to protect the marine environment, established in articles 192 and 194 of the UN Convention on the Law of the Sea. The rule of “due respect to navigation” in this regard should be interpreted to mean that the restrictions and requirements imposed by the laws and regulations of the coastal State must be primarily aimed at ensuring the safety and protection of the marine environment in harsh climatic conditions, without being at the same time discriminatory, unreasonable and excessive.

Peridynamic Simulation of the Penetration of an Ice Sheet by a Vertically Ascending Cylinder

The vertical ice breaking of marine structures in ice-covered areas involves the deformation and failure of an ice sheet. Different from the existing conventional scenarios where the ice sheet is used as a transportation and support medium, the damage to the ice sheet will be more severe when a structure penetrates the ice sheet from below, due to the lack of elastic support from the fluid above the ice sheet. In order to investigate the failure mode of the ice sheet and the ice load characteristics during vertical penetration, a mesh-free bond-based peridynamic method is used in this paper to simulate the mechanical behaviors of the ice sheet. The cracks simulated in this study exhibit a higher level of similarity to experimental results, which improves the accuracy of the ice load. The numerical model established shows satisfactory applicability for the analysis of penetration failure of an ice sheet. In addition, the influence of ice thickness, impact velocity, and cylinder diameter on the failure characteristics of the ice sheet and breakthrough load are analyzed. The results of a parametric study indicate that the relationship between ice thickness and breakthrough load, as well as the relationship between load area and breakthrough pressure, can both be fitted using quadratic functions.

The role of China in protecting the Arctic against pollutions from vessels: a legal perspective.

In the past decade, global climate change and the rapid melting of polar ice have dramatically transformed the Arctic landscape from a vast ice-covered area to a seasonally navigable sea. This accessibility has sparked increased commercial activity, posing a threat from various pollutants, particularly from vessel sources. Given China's profound interests in Arctic shipping, its involvement may face resistance from Arctic states, and therefore, it is important for China to ensure that its presence benefits local communities and states. This study explores China's role in shaping the international legal landscape to protect the Arctic from vessel-source pollutions. The intricate interplay between China's economic interests, maritime security concerns, and environmental commitments in the Arctic underscores China's potential role. By aligning with existing international legal structures, such as UNCLOS and MARPOL, China has already started to demonstrate its commitment to preserving the Arctic environment. This study assesses and discusses the potentially strategic importance of China's involvement in influencing legal regimes, offering a crucial contribution to global efforts to preserve this vital region.

Interannual variability of ice cover across Davis Strait and the Labrador Sea for the period from 1979 to 2023

In conditions of rapid development of trade and transport communications, the issue of navigation through ice regime zones became of greater importance. In particular, reduction of the area of ice cover in the Canadian Arctic because of global warming opens up favourable prospects for further development of maritime shipping in this zone. Considering that the routes through the Northwest Passage are the shortest ones of all the routes connecting the Atlantic and Pacific oceans, it is clear that all aspects of this topic are of great importance and relevance. This especially applies to the aspects dedicated to studying the characteristics of appearance, formation, concentration, physical characteristics, trajectory of ice movement and forecasting the area of the ice cover in a given zone, i.e. the characteristics affecting the conditions of ice navigation and serving as determining factors in terms of navigation safety.
 The research examines some of these issues, namely the spread of the ice cover during the period of its maximum formation across Davis Strait and the Labrador Sea (where the routes through the Northwest Passage start) and the establishment of statistical relations between the ice spread and the temperatures of surface water and surface air. The research method to be used: synoptic-climatic and statistical analysis of numerical series of ice cover deviations from its average limit as of April 15 over the period of 1979-2023 within the zone in study.
 Based on the set goal, the study processed raw data on distribution of ice cover across Davis Strait and the Labrador Sea for the period of 1979-2023 and completed its statistical analysis. The results of the analysis showed presence of a statistically significant negative trend and cyclical fluctuations with periods of 3-6, 9, 10 and 13 years in relation to the interannual variability of ice cover distribution for the studied period. Positive trends are also observed in the interannual variability of surface water temperature and surface air temperature. After bringing the original series to a quasi-stationary form, a correlation analysis of the relationships between the ice cover distribution and the temperature of water and air was carried out. The results of the analysis determined zones and points with statistically significant correlation coefficients between them during the year. It turned out that the highest values of coefficients are observed from December to March, and the maximum one occurs in March.
 Systematization and analysis of the ice field across Davis Strait and the Labrador Sea during the period of maximum development made it possible to establish that the spread of ice between 60° and 55° north parallels was the most stable during the studied period, and the least stable was observed in the area below 55° north parallel.
 The results of the conducted research open up prospects for development of methods for forecasting the distribution of ice cover across Davis Strait and the Labrador Sea. This will make ice navigation in this area safer.

Numerical Study on Wave–Ice Floe Interaction in Regular Waves

The marginal ice zone (MIZ) is located at the junction of ice-covered areas and open water, where waves cause ice floes to break up and change their state of motion, thus threatening the safety of ships navigating the ice. This study employs the Structured Arbitrary Lagrangian–Eulerian (S-ALE) method and the numerical wave-making method based on dynamic boundary conditions to numerically examine the motion response of ice floes in waves. The longitudinal motion of ice floes in waves can be classified into two distinct states, namely irregular and regular, depending on the wavelength. In the short-wave range, the ice floes exhibit primarily irregular motion, whereas in the long-wave range, their motion becomes regular, resembling that of isolated ice floes. The longitudinal motion response of the ice floes remains unaffected by their size. However, the longitudinal velocity, surge velocity, and displacement of the ice floes are influenced by the wavelength. Furthermore, the numerical calculations are compared to the model test conducted in a towing tank using paraffin artificial ices, revealing a qualitative agreement between the experimental and numerical results.

From winter to late summer in the northwestern Barents Sea shelf: Impacts of seasonal progression of sea ice and upper ocean on nutrient and phytoplankton dynamics

Strong seasonality is a key feature of high-latitude systems like the Barents Sea. While the interannual variability and long-term changes of the Barents Sea are well-documented, the seasonal progression of the physical and biological systems is less known, mainly due to poor accessibility of the seasonally ice-covered area in winter and spring. Here, we use an extensive set of physical and biological in situ observations from four scientific expeditions covering the seasonal progression from late winter to late summer 2021 in the northwestern Barents Sea, from fully ice-covered to ice-free conditions. We found that sea ice meltwater and the timing of ice-free conditions in summer shape the environment, controlling heat accumulation, light and nutrient availability, and biological activity vertically, seasonally, and meridionally. In March and May, the ocean north of the Polar Front was ice-covered and featured a deep mixed layer. Chlorophyll-a concentrations increased strongly from March to May along with greater euphotic depth, indicating the beginning of the spring bloom despite the absence of surface layer stratification. By July and in September, sea ice meltwater created a shallow low-density surface layer that strengthened stratification. In open water, chlorophyll-a maxima were found at the base of this layer as surface nutrients were depleted, while in the presence of ice, maxima were closer to the surface. Solar heating and the thickness of the surface layer increased with the number of ice-free days. The summer data showed a prime example of an Arctic-like space-for-time seasonal variability in the key physical and biological patterns, with the summer situation progressing northwards following sea ice retreat. The amount of sea ice melt (local or imported) has a strong control on the conditions in the northwestern Barents Sea, and the conditions in late 2021 resembled pre-2010 Arctic-like conditions with high freshwater content and lower ocean heat content.

Prevention and control of ship-source pollution in the Arctic shipping routes: challenges and countermeasures

Ship-source pollution is one of the important contributors to marine environment pollution. Because the legal status of the Arctic shipping routes is not clear, there is a considerable degree of dispute in the application of the rules on the prevention and control of ship-source pollution. The increased melting of sea ice undermines the legal legitimacy of the “ice-covered areas” clause under the United Nations Convention on the Law of the Sea. The conflict between the application of the Polar Code and “ice-covered areas” will also reach an initial conclusion in the context of melting sea ice. However, the inadequacy of ship-source pollution rules in the Polar Code hampers its application, which has led to a negative impact on the more active role in the governance of pollution from Arctic shipping. For replying to the Challenges in the prevention of ship-source pollution in Arctic shipping routes, the relevant rules of the Polar Code need to be further improved, while a more binding HFO ban according to ship types needs to be applied. Therefore, a more important role in the future Arctic governance mechanism will be played by the enhanced enforcement of the Polar Code, meanwhile, the target for uniform international regulation of preventing and controlling ship-source pollution in Arctic shipping routes should be achieved.

New particle formation leads to enhanced cloud condensation nuclei concentrations on the Antarctic Peninsula

Abstract. Few studies have investigated the impact of new particle formation (NPF) on cloud condensation nuclei (CCN) in remote Antarctica, and none has elucidated the relationship between NPF and CCN production. To address that knowledge gap, we continuously measured the number size distribution of 2.5–300 nm particles and CCN number concentrations at King Sejong Station on the Antarctic Peninsula from 1 January to 31 December 2018. Ninety-seven NPF events were detected throughout the year. Clear annual and seasonal patterns of NPF were observed: high concentration and frequency of nucleation-mode particles in summer (December–February: 53 NPF cases) and undetected nucleation-mode particles in winter (June–August: no NPF cases). We estimated the spatial scale of NPF by multiplying the time during which a distinct nucleation mode can be observed at the sampling site by the locally measured wind speed. The estimated median spatial scale of NPF around the Antarctic Peninsula was found to be approximately 155 km, indicating the large scale of NPF events. Air back-trajectory analysis revealed that 80 cases of NPF events were associated with air masses originating over the ocean, followed by sea-ice (12 cases), multiple (3 cases), and land (2 cases) regions. We present and discuss three major NPF categories: (1) marine NPF, (2) sea-ice NPF, and (3) multiple NPF. Satellite estimates for sea-surface dimethylsulfoniopropionate (DMSP; a precursor of gaseous dimethyl sulfide) data showed that the production of oceanic biogenic precursors could be a key component in marine NPF events, whereas halogen compounds released from ice-covered areas could contribute to sea-ice NPF events. Terrestrial sources (wildlife colonies, vegetation, and meltwater ponds) from Antarctica could affect aerosol production in multiple air masses. Out of 97 observed NPF events, 83 cases were characterized by the simultaneous increase in the CCN concentration by 2 %–270 % (median 44 %) in the following 1 to 36 h (median 8 h) after NPF events. Overall, Antarctic NPF events were found to be a significant source of particles with different physical characteristics and related to biogenic sources in and around the Antarctic Peninsula, which subsequently grew to cloud condensation nuclei.

A review of aerial survey density estimates of bearded seals (Erignathus barbatus) in the Canadian Arctic highlights important knowledge gaps and research needs

AbstractThere has been significant sea ice loss in the Arctic as a result of climate change, with measurable impacts on available habitat for ice-obligate marine mammals. Bearded seals (Erignathus barbatus) have a circumpolar distribution and primarily inhabit coastal areas of shallower depths with seasonal pack ice cover. However, there is limited information and no formal estimates on population abundance and densities of bearded seals within Canada. Here, we review historic field reports and publications from aerial surveys conducted from 1974 to 2022 to compile the density and abundance estimates of bearded seals across Canadian waters. Aerial surveys for marine mammals have been flown in several areas across the Canadian Arctic, including the Beaufort Sea (1974–2006), Canadian High Arctic (1979–2022), Baffin Bay-Davis Strait (1979–2014), and the Hudson Complex (1994–2017). After reviewing all published data sources, we report that the density of bearded seals in Canada were highest (and highly variable) in the Beaufort Sea (0.01–8.68 seals*km−2), then in Baffin Bay-Davis Strait (0.004–8.3 seals*km−2), and lowest and less variable inter-annually in the Hudson Complex (0.02 to 0.12 seals*km−2) at the time of these surveys. We also determined that bearded seals are more often found in areas of patchy ice cover (50–75%) with shallow water depths ≤ 500 m. Further, this review identifies regions within the Canadian Arctic and sub-Arctic that require updated aerial survey information. Quantifying the abundance and density estimates of bearded seals in Canada is essential for monitoring population status over time to better understand how this species is responding to environmental variation from anthropogenic activity and climate change.

Singlet oxygen-induced alteration of bacteria associated with phytodetritus: Effect of irradiance.

Contrasting irradiation of senescent cells of the diatom Thalassiosira sp. in association with the bacterium Pseudomonas stutzeri showed the effect of intensity of irradiance on the transfer of singlet oxygen (1 O2 ) to bacteria attached to phytoplanktonic cells. Under low irradiances, 1 O2 is produced slowly, favors the oxidation of algal unsaturated lipids (photodynamic effect), and limits 1 O2 transfer to attached bacteria. However, high irradiances induce a rapid and intense production of 1 O2 , which diffuses out of the chloroplasts and easily reaches the attached bacteria, where it efficiently oxidizes their unsaturated membrane components. Analysis of numerous sinking particle samples collected in different regions of the Canadian Arctic showed that the photooxidation state of attached bacteria increased from ice-covered areas to open water, in agreement with in vitro results. Photooxidation of bacteria appeared to be particularly intense in sea ice, where the sympagic algae-bacteria association is maintained at relatively high irradiances for long periods of time.