Heavy Ice Conditions Research Articles

Arctic Sea Ice Loss Modulates the Surface Impact of Autumn Stratospheric Polar Vortex Stretching Events

AbstractThe cold Eurasia has been proposed to be closely linked to the weakening of the stratospheric polar vortex (SPV), however, how the Arctic sea ice modulates the surface impacts of the weak SPV is unclear. This study explores the critical modulating role of reduced Arctic sea ice in the surface cooling response to SPV stretching events in autumn. Here, through ERA5 reanalysis and Whole Atmosphere Community Climate Model simulations, we show that Eurasian cold events are more likely (45%) to occur in days 30–50 after the onset of SPV stretching events under lower Barents‐Kara Seas (BKS) sea ice conditions, in contrast to under heavy BKS sea ice conditions when robust surface cooling is absent. The stratospheric and tropospheric pathways explain 46.8% and 53.2% of the total variance of Siberian coldness, respectively. The downward extension of anomalous stratospheric wave‐2 ridge to the troposphere intensifies the Arctic‐North European high, favoring the subsequent colder Siberia.

Theoretical foundations of freeing ships from heavy ice conditions

The topic of the study is to prevent damage to the ships hulls when sailing in polar waters in severe ice conditions, which is a dangerous situation that threatens environmental pollution and possible death of the vessel, its passengers and crew. It is noted that the intensive development of ice navigation in the development of the Arctic regions of the Russian Federation and other polar waters requires the development and improvement of methods for freeing ships trapped in heavy ice. Navigation of vessels in severe ice conditions is accompanied by significant difficulties and dangers for the vessel, its passengers and crew. This situation can be significantly aggravated if, at a certain stage of navigation in ice conditions, heavy ice begins to move, leading to compression of the ice channel in which the vessel is located. At the same time, the risk of the vessel hull destruction, the creation of water leakage and the possible death of the vessel, its passengers and crew increases, as well as environmental pollution occurs. The theoretical foundations of freeing a vessel from severe ice conditions, based on the principles of rocking and pushing, as well as cutting ice, clamping the vessel, which have proven their effectiveness in other fields of science and technology, are discussed in the paper. The use of the vessel theory apparatus and the experience of ice-breaking assistance make it possible to substantiate the possibility of effective application of methods of rocking, pushing and chopping ice to release ships caught in severe ice conditions. The theoretical possibility of using combinations of the operation of the ballast system, cargo booms and cranes, special actions of the crew trapped in the ice of the vessel, as well as its interaction with icebreakers and other vessels for cutting the clamping ice, rocking and pushing, increasing the efficiency of freeing the vessel from severe ice conditions, is shown. The materials of the paper can be used to develop practical recommendations for freeing ships from heavy ice conditions independently and using icebreakers and other vessels.

CAGE20-8 Cruise Report: Natural gas seepage and past sea ice variability on the NE Greenland margin

CAGE20-8 cruise onboard RV “Kronprins Haakon” aimed to survey the natural seepage of methane along the NE Greenland margin. Based on multibeam echosounder surveys, water column mapping for gas flares, and shallow seismic, gravity coring and multicoring were conducted. Due to heavy ice conditions, the vessel did not reach the shelf, however, survey along the continental slope were conducted. From a number of acoustic profiles and sediment cores, we will pursue the investigations of natural seepage related to glacial variability and sea ice fluctuations over the coming months. The cruise may be known as: CAGE20_8

Environmental DNA metabarcoding reveals seasonal and spatial variation in the vertebrate fauna of Ilulissat Icefjord, Greenland

Ilulissat Icefjord in Greenland is experiencing the effects of climate change, with the Sermeq Kujalleq glacier being one of the fastest-moving and most productive ice streams in Greenland. This is likely affecting the distribution of species in the fjord, including those important to local fisheries. Due to heavy ice conditions, few studies on environmental and ecological conditions exist from the fjord. However, new techniques such as environmental DNA (eDNA) metabarcoding now allow deeper insight into the fjord system. Here, we combine local ecological knowledge with data on hydrographic conditions, stable isotopes (δ18O), and eDNA metabarcoding to investigate the spatial and seasonal distribution of marine fish and mammals inside Ilulissat Icefjord. Our eDNA results support local observations that Arctic char migrate to the southern fjord during summer, harp seals forage in large herds in the fjord system, polar cod is the dominant prey fish in the area, and Greenland shark likely does not reside in the fjord system. Lower predation pressure in the Icefjord, due to the absence of Greenland shark and polar bears as well as limited fishing/hunting, is presumably one of the reasons why ringed seals and Greenland halibut are larger in the Icefjord. Furthermore, our results indicate that in summer, the southern branch of the fjord system has a more diverse community of vertebrates and different water masses than the northern branch and main fjord, indicating a time lag between inflows to the different branches of the fjord system. Our approach highlights the value of combining local ecological knowledge with scientific research and represents a potential starting point for monitoring biological responses in Ilulissat Icefjord associated with climate-induced changes.

Сжатия ледяного покрова в Печорском море: природное явление и его влияние на морские операции

The Pechora Sea is an essential region of the Russian Arctic shelf in terms of hydrocarbon production and cargo transit along the NSR (mainly from the Ob’ Bay area). Occasionally, heavy ice conditions form in this area, manifested in the compression of the ice cover, which lead to a serious complication of navigation and operation of vessels supporting the Prirazlomnaya ice resisting platform. Based on the analysis of various sources, the authors consider the processes of formation of severe ice conditions in 2003 and 2018, as well as their impact on the operation of ships. They demonstrate that the only vessel able to operate steadily in such conditions is a nuclear icebreaker. The authors suggest that ice compressions of varying intensity are quite typical for the area and can repeat occasionally

Arctic sea ice variation in the Northwest Passage in 1979–2017 and its response to surface thermodynamics factors

Sea ice conditions in the Canadian Arctic Archipelago (CAA) play a key role in the navigation of the Northwest Passage (NWP). Limited by observed sea ice thickness data, the research of temporal and spatial variation of sea ice in the NWP is insufficient. Based on the observed sea ice concentration and simulated thickness data, the temporal and spatial characteristics of sea ice concentration, extent and thickness from 1979 to 2017 in the NWP of the CAA were studied. The more specific pathways of the northern and southern routes of the NWP were evaluated. Against the background of the rapid retreat of Arctic sea ice, the 39-year observed sea ice concentration and extent of the NWP exhibited a relatively large decreasing trend in summer and fall, while heavy sea ice conditions were maintained in winter and spring, with slightly increasing trend in some subregions. The sea ice thickness in most subregions of the NWP showed a decreasing trend, with exception of Lancaster Sound. The sea ice thickness was larger along the northern route than the southern routes. The significant correlation (p < 0.05) between sea ice and surface air temperature (SAT) and sea surface temperature (SST) in the NWP suggested that the surface thermodynamic factors had a greater impact on sea ice in the summer and fall, and the variations of sea ice concentration were more closely correlated with the surface thermodynamic factors than sea ice thickness. The SST had a higher correlation with sea ice concentration than SAT, while SAT exhibited a higher correlation with sea ice thickness than SST. The remaining sea ice concentration and thickness in the fall, associated with the summer and fall SAT and SST, contributed to the formation of sea ice in the following winter and spring. The heat content and mixed layer depth were also be considered as the vertical thermodynamic factors to the sea ice condition in the NWP.

VARIABILITY OF THE ICE CONDITIONS IN THE CHUKCHI SEA AND THEIR LINKS WITH ARCTIC OSCILLATION

Variability of the ice conditions in the Chukchi Sea is considered in various scales on the basis of all available information for 1950–2017. Its dependence on the atmospheric circulation patterns measured with the Arctic Oscillation index is shown. Tendency to the ice reducing has intensified in the early 21st century in the Chukchi Sea that is accompanied with changes in its seasonal development, as shift of the ice destruction beginning from June to July, gradual increasing of the ice destruction rate till September, shift of the ice formation beginning from September to October, and delay of the ice spreading over entire sea area from November to December. Relationship of the ice conditions in the Chukchi Sea on summer phase of Arctic oscillation is detected: the maximum positive values of the index always correspond with heavy ice conditions, the minimum values of the index correspond with low-ice conditions only, and various ice conditions are observed in other years without neither positive nor negative extremities of Arctic oscillation. However, winter phase of Arctic oscillation does not affect on the ice conditions in the Chukchi Sea in June-November.

Receding ice drove parallel expansions in Southern Ocean penguins

Climate shifts are key drivers of ecosystem change. Despite the critical importance of Antarctica and the Southern Ocean for global climate, the extent of climate-driven ecological change in this region remains controversial. In particular, the biological effects of changing sea ice conditions are poorly understood. We hypothesize that rapid postglacial reductions in sea ice drove biological shifts across multiple widespread Southern Ocean species. We test for demographic shifts driven by climate events over recent millennia by analyzing population genomic datasets spanning 3 penguin genera (Eudyptes, Pygoscelis, and Aptenodytes). Demographic analyses for multiple species (macaroni/royal, eastern rockhopper, Adélie, gentoo, king, and emperor) currently inhabiting southern coastlines affected by heavy sea ice conditions during the Last Glacial Maximum (LGM) yielded genetic signatures of near-simultaneous population expansions associated with postglacial warming. Populations of the ice-adapted emperor penguin are inferred to have expanded slightly earlier than those of species requiring ice-free terrain. These concerted high-latitude expansion events contrast with relatively stable or declining demographic histories inferred for 4 penguin species (northern rockhopper, western rockhopper, Fiordland crested, and Snares crested) that apparently persisted throughout the LGM in ice-free habitats. Limited genetic structure detected in all ice-affected species across the vast Southern Ocean may reflect both rapid postglacial colonization of subantarctic and Antarctic shores, in addition to recent genetic exchange among populations. Together, these analyses highlight dramatic, ecosystem-wide responses to past Southern Ocean climate change and suggest potential for further shifts as warming continues.

Modelling of the passive turning of a turret moored vessel in conditions of compact ice

The concept of the offshore oil and gas field development using floating ship-shaped platforms, frequently named floating production units (FPU further), with turret mooring is widely used in the world, including regions with harsh environment. The direct transfer of this concept to the Arctic seas is not possible, mostly due to the difficulties of maintaining a weathervaning, or passive turning regime in heavy ice conditions. The main danger relates to the fact that the expected FPU rotation under the action of high ice loads can be accompanied by a translational displacement of the FPU away from the mooring point. As a result, the mooring system may reach an overloaded state until the FPU turns to a favourable position relative to the ice drift direction. In the paper, we are focused on the investigation of a mathematical model of the passive FPU turning on a spot under the assumption that the ice cover is described by a rigid-plastic continuum. The study is performed both analytically and by numerical simulations. A number of specific FPU motion patterns are analytically derived from the model in quasi-static approximation in the form of successive limit states of the system FPU – ice continuum. Some results of the corresponding numerical simulation are presented that confirm the existence of similar solutions in the full dynamic setting of the problem. A partial parametric analysis of the problem is also performed.

Early evaluation of impacts of cold waves and floods during winter 2018 in France

ObjectiveThe presentation describes the results of the daily monitoring of health indicators conducted by the French public health agency during the major floods and the cold wave that occurred in January 2018 in France, in order to early identify potential impact of those climatic events on the population.IntroductionThe Seine River rises at the north-East of France and flows through Paris before emptying into the English Channel. On January 2018 (from 22th January to 11th February, Weeks 4 to 6), major floods occurred in the Basin of Seine River, after an important rainy period. This period was also marked by the occurrence on the same area of a first cold wave on Week 6 (from 5th to 7th February), including heavy snowfall and ice conditions from 9th to 10th February. A second similar cold wave occured from 28th February and 1st March.Floods of all magnitude are known to have potential health impacts on population [1], both at short, medium and long term both on physical (injuries, diarrhoeal disease, Carbon Monoxyde poisoning, vector-borne disease) and mental health. Extreme cold weather have also the potential to further impact on human health through direct exposure to lower temperatures, and associated adverse conditions, such as snow and ice [2]. Such situations may be particularly associated to direct impact like hypothermia, frostbite and selected bone/joint injuries).MethodsSince 2004, the French Public Health Agency (Santé publique France) set up a national syndromic surveillance system SurSaUD, enabling to ensure morbidity and mortality surveillance [3]. In 2018, morbidity data were daily collected from a network involving about 700 emergency departments (ED) and 58 emergency general practitioners’ associations SOS Médecins. 92% of the national ED attendances and 95% of national SOS Médecins visits are caught by the system.Both demographic (age and gender), administrative (date and location of consultation, transport) and medical information (chief complaint, medical diagnosis using ICD10 codes in ED and specific thesauri in SOS Médecins associations, severity, hospitalization after discharge) are recorded for each patient.The daily and weekly evolution of the number of all-cause ED attendances and SOS Médecins consultations during the flooding period were compared to the evolution on the two previous years. The number of hospitalisations after ED discharge was also monitored. The immediate health impact of floods and cold waves was assessed by monitoring eight syndromic indicators: gastroenteritis, carbon monoxide poisoning, burnt, stress, faintness, drowning, injuries and hypothermia.Analyses were performed by age group (&lt;15 years, 15-64 years, more than 65 years) and at different geographical levels (national, Paris region and districts located in the Basin of Seine River).ResultsIn 2018, syndromic surveillance did not show any major impact on all-cause ED attendances and SOS Médecins consultations from week 4 to week 6, neither in Paris area nor in other areas along the Seine River. The recorded numbers were comparable to the two precedent years in all age groups.A decrease of the all-cause ED attendances was observed during the 1st day with ice conditions in Normandy and Paris, mainly in children and adults aged 15-64 years.During week 6 in Paris area, an increase of ED attendances was observed for injuries (+4% compared to the past weeks – figure 1) and to a lesser extent for hypothermia and frostbite (16 attendances compared to less than 9 for the past weeks). Similar increase in injuries were observed in Normandy during the second cold wave (Figure 1).ConclusionsDuring the flood episode, the rising water level was slow with foreseeable evolution, compared to other sudden flood events occurring in south of France in 2010 due to violent thunderstorms. This progressive evolution allows French authority to deploy wide specific organization in order to mitigate impact on concerned populations. That may explain the absence impact observed in ED at regional and national levels during the flood disaster. The evolution of injuries during 2018 episode is attributable to the cold wave that occurred simultaneously.As the French syndromic surveillance system is implemented on the whole territory and collects emergency data routinely since several years, it constitutes a reactive tool to assess the potential public health impact of both sudden and predictable disasters. It can either contribute to adapt management action or reassure decision makers if no major impact is observed.

New records of mummified crabeater seals on islands bordering Admiralty Sound, Weddell Sea

AbstractNinety-six mummified crabeater seals discovered at Seymour Island (Isla Marambio) are reported. Each specimen was georeferenced, photographed and assigned to five different taphonomic states. Previous work stated that seals at Seymour Island get stranded inland around the breeding season. However, it is not clear if the species breeds in this area. The abundance of crabeater seals and the ice condition along Admiralty Sound (Estrecho Bouchard) were obtained by aerial surveys during spring (2015–17). It appears that the species uses the strait as a passage to breeding grounds. Under heavy ice conditions, the seals become stranded in the middle section of this strait and wander inland through a valley that represents the mouth of an ephemeral stream that ends at the pack ice level. This situation was observed in 2014 and 2015 when recently dead seals were found, evidencing that this natural trap is still active. Nonetheless, in 2016 and 2017, during an early breakup of Admiralty Sound, the seals that remained in the area were more numerous than in 2015 but they did not get stranded inland. This early breakup may encourage the seals to breed there in the presence of open water areas with ice floes.

Early assessment of public health impacts of major floods in France in June 2016 and winter 2018

Introduction The Seine River rises at the northeast of France and flows through Paris before emptying into the English Channel. On June 2016 (week 22) and January 2018 (weeks 4 to 6), major floods occurred in the Basin of Seine River, after important rainy periods. The second period was also marked by the occurrence on the same area of a cold wave including heavy snowfall and ice conditions on week 6. Floods are known to have potential health impacts on population living in those regions, both at short-, medium- and long-term both on physical and mental health. The objective of the study is to present the results of the daily monitoring of health indicators conducted by the French public health agency (SpFrance) during the two major floods, in order to early identify potential impact of those disasters on the population. Methods Since 2004, SpFrance set up a national syndromic surveillance system SurSaUD, enabling to ensure morbidity and mortality surveillance. Morbidity data are daily collected from a network involving emergency departments (ED) and emergency general practitioners’ associations SOS Medecins. Both administrative (age, gender, date and location of consultation) and medical information (medical diagnosis using ICD10 codes in ED and specific thesauri in SOS Medecins associations) are recorded for each patient. The daily and weekly evolution of the number of all-cause ED attendances and SOS Medecins consultations during the flood periods were compared to the evolution on the two previous years. The number of hospitalisations after ED discharge was also monitored. The immediate health impact of floods was assessed by monitoring eight syndromic indicators related to flood exposure: gastroenteritis, carbon monoxide poisoning, burnt, stress, faintness, drowning, injuries and hypothermia. Analyses were performed by age group and at different geographical levels (national, Paris region and districts located in the Basin of Seine River). Results During week 22-2016, a decrease of total number of ED attendances all ages and more specifically for children aged less than 15 years old was observed in region Centre (−15% compared with weeks 21 and 23) and to a lesser extent in Paris area (−4% and −12% respectively compared with week 21 and week 23). Locally, in the most impacted cities, an increase of total ED attendances was also observed for people aged 65 years and more. At the opposite, the number of all-cause SOS Medecins consultations remained stable in all age groups. Analysis by syndromic indicator did not show unusual variations during the first flood period. In 2018, syndromic surveillance did not show any major impact on all-cause ED attendances and SOS Medecins consultations from week 4 to week 6, neither in Paris area nor in other areas along the Seine River. The numbers were comparable to the two precedent years in all age groups. During week 6 in Paris area, an increase of ED attendances was observed for injuries (+4% compared to the past weeks) and to a lesser extent for hypothermia (16 attendances compared to less than 9 for the past weeks). Conclusion For both flood episodes the rising water level was slow with foreseeable evolution, compared to other sudden flood events occurring in south of France in 2010 due to violent thunderstorms. This progressive evolution allows French authority to deploy wide specific organization in order to mitigate impact on concerned populations. That may explain the limited impact observed during the two flood disasters. The evolution of injuries during 2018 episode is attributable to the cold wave that occurred simultaneously. As the French syndromic surveillance system is implemented on the whole territory and collects emergency data routinely since several years, it constitutes a reactive tool to assess the potential public health impact of both sudden and predictable disasters. It can either contribute to adapt management action or reassure decision makers if no major impact is observed.

Моделирование систем арктического морского транспорта: основы междисциплинарного подхода и опыт практических работ

Development of new offshore projects in the Arctic begins with comprehensive analysis of Marine Transport System’s (MTS) performance. At the same time researchers with different professional orientation (shipbuilders, logisticians, economists and managers etc.) are often have narrow view while making their investigations of MTS, focusing mostly at corresponding familiar sides of the system. It leads to specific “disproportional” description of MTS’s when some components considered in detail but other are out of investigation that in some cases may result in inaccurate conclusions. This makes authors sure that the only proper approach to investigate complex arctic MTS should be multidisciplinary. Article contains the description of integrated R&amp;D project fulfilled at State Krylov Research Centre and devoted to realization of multidisciplinary methodology and corresponding software for arctic MTS design and analysis. Integrated software solution is based on object-oriented paradigm and combines such scientific areas as geographic information systems (GIS), shipbuilding disciplines, discrete event and agent-based simulation models. Theoretical base of the solution and its architecture envelops the following subject fields: ship design and fleet sizing, resistance and propulsion of ships including ice-going capabilities, vessel routing in ice, scheduling, downstream and upstream logistics, navigation process simulation, environment conditions stochastic modeling, operation research, queue theory, economy and management. Software has a modular structure with open and expansible architecture, which makes possible to add new functionality and upgrade existing program blocks in accordance with demands of specific project. Simulation model serve as the center of multidisciplinary integration because this technology allows reproducing behavior of different objects of MTS under dynamic conditions. Realized in AnyLogic ® framework simulation model replicates vessel operation process according to individual schedule generated by special planning component. Vessel’s activities simulated in modeled time with consideration of special aspects of operational planning and resolving accidents. Main model also includes specialized sub-models that provide opportunity to describe many local dynamic essences such as processes of offshore drilling and production, freeze-up of channel in fast ice, different ship interaction aspects, “weather windows” in ports etc. Number of instances are also given in the article, they allows to conclude that adequate and consistent model of MTS working in heavy ice-conditions or having complex organization scheme could be obtained only by means of simulation modeling under multidiscipline approach.

Fall-winter cyclogenesis over the Pacific Ocean and Far-Eastern Seas and its influence on development of the sea ice

Cyclonic activity patterns over the North Pacific in fall-winter have changed prominently in the last two decades (since the middle 1990s) due to a gradual westward shift of the Aleutian Low and Siberian High. The maximum of cyclonic activity was observed in the eastern Bering Sea in the 1990s, but strong winter cyclones moved mostly to the Okhotsk Sea and Kuril Islands in the late 2000s. These changes caused the ice regime change: the ice cover was relatively low in the Bering Sea in opposite to heavy ice conditions in the Okhotsk Sea until the mid-2000s, but the ice cover decreased in the Okhotsk Sea and increased in the Bering Sea when tracks of cyclones had changed. Some changes concern the moderate latitudes, too, because cyclones in the Bering Sea made a cooling effect on the North Pacific area southward from Aleutian Islands but those in the Okhotsk Sea cool the Japan Sea area.

Determination of global ice loads on the ship using the measured full-scale motion data

This paper describes the whole procedures to determine ice-induced global loads on the ship using measured full-scale data in accordance with the method proposed by the Canadian Hydraulics Centre of the National Research Council of Canada. Ship motions of 6 degrees of freedom (dof) are found by processing the commercial sensor signals named Motion Pak II under the assumption of rigid body motion. Linear accelerations as well as angular rates were measured by Motion Pak II data. To eliminate the noise of the measured data and the staircase signals due to the resolution of the sensor, a band pass filter that passes frequencies between 0.001 and 0.6 Hz and cubic spline interpolation resampling had been applied. 6 dof motions were computed by the integrating and/or differentiating the filtered signals. Added mass and damping force of the ship had been computed by the 3-dimensional panel method under the assumption of zero frequency. Once the coefficients of hydrodynamic and hydrostatic data as well as all the 6 dof motion data had been obtained, global ice loads can be computed by solving the fully coupled 6 dof equations of motion.Full-scale data were acquired while the ARAON rammed old ice floes in the high Arctic. Estimated ice impact forces for two representative events showed 7–15 MN when ship operated in heavy ice conditions.

Spring conditions and habitat use of beluga whales (Delphinapterus leucas) during arrival to the Mackenzie River Estuary

Climate change is expected to impact Arctic marine mammals, as they may be particularly vulnerable to large annual variability in the environment. Beluga whales (Delphinapterus leucas) occupy the circumpolar Arctic year-round, and seasonal movement patterns in this landscape are closely linked to sea ice and changing conditions. Here, we examine the association between beluga spring locations along the Mackenzie Shelf and three relevant habitat variables: sea ice (total concentration, floe size, and distance to ice edge), bathymetry and turbidity. Beluga locations in 2012 and 2013 were analyzed across the study area, as well as in three discrete subareas of the Mackenzie Shelf: Shallow Bay, Kugmallit Bay and Tuktoyaktuk Peninsula. In both years, beluga were found more than expected by chance in locations of open water/light ice concentrations and medium ice floes, and displayed a significant association with turbid water (i.e., increased freshwater flow). Largely ice-free conditions in 2012 led to a wide variation in habitat use in all three subareas. Beluga whales in 2012 preferred the ice edge and were found in heavier ice concentrations, larger floes and high turbidity water in the Shallow Bay subarea. Open water environments were preferred by beluga found in the Kugmallit Bay subarea. In contrast, heavy ice conditions in 2013 resulted in restricted habitat use and selection of shallow depth (<50 m) and low levels of turbidity. These results provide knowledge on spring habitat selection as well as insight into the adaptability of beluga under expected changes associated with climate and human activity in the Beaufort Sea.

Environmental responses of the Northeast Antarctic Peninsula to the Holocene climate variability

In this study, we present a unique high-resolution Holocene record of oceanographic and climatic change based on analyses of diatom assemblages combined with biomarker data from a sediment core collected from the Vega Drift, eastern Antarctic Peninsula (EAP). These data add to the climate framework already established by high-resolution marine sedimentary records from the Palmer Deep, western Antarctic Peninsula (WAP). Heavy sea ice conditions and reduced primary productivity were observed prior to 7.4 ka B.P. in relation with the proximity of the glacial ice melt and calving. Subsequent Holocene oceanographic conditions were controlled by the interactions between the Westerlies-Antarctic Circumpolar Current (ACC)-Weddell Gyre dynamics. A warm period characterized by short seasonal sea ice duration associated with a southern shift of both ACC and Westerlies field persisted until 5 ka B.P. This warm episode was then followed by climate deterioration during the middle-to-late Holocene (5 to 1.9 ka B.P.) with a gradual increase in annual sea ice duration triggered by the expansion of the Weddell Gyre and a strong oceanic connection from the EAP to the WAP. Increase of benthic diatom species during this period was indicative of more summer/autumn storms, which was consistent with changes in synoptic atmospheric circulation and the establishment of low- to high-latitude teleconnections. Finally, the multicentennial scale variability of the Weddell Gyre intensity and storm frequency during the late Holocene appeared to be associated with the increased El Nino–Southern Oscillation frequency.

Potential source regions and processes of aerosol in the summer Arctic

Abstract. Sub-micrometer particle size distributions measured during four summer cruises of the Swedish icebreaker Oden 1991, 1996, 2001, and 2008 were combined with dimethyl sulfide gas data, back trajectories, and daily maps of pack ice cover in order to investigate source areas and aerosol formation processes of the boundary layer aerosol in the central Arctic. With a clustering algorithm, potential aerosol source areas were explored. Clustering of particle size distributions together with back trajectories delineated five potential source regions and three different aerosol types that covered most of the Arctic Basin: marine, newly formed and aged particles over the pack ice. Most of the pack ice area with &lt; 15% of open water under the trajectories exhibited the aged aerosol type with only one major mode around 40 nm. For newly formed particles to occur, two conditions had to be fulfilled over the pack ice: the air had spent 10 days while traveling over ever more contiguous ice and had traveled over less than 30% open water during the last 5 days. Additionally, the air had experienced more open water (at least twice as much as in the cases of aged aerosol) during the last 4 days before arrival in heavy ice conditions at Oden. Thus we hypothesize that these two conditions were essential factors for the formation of ultrafine particles over the central Arctic pack ice. In a comparison the Oden data with summer size distribution data from Alert, Nunavut, and Mt. Zeppelin, Spitsbergen, we confirmed the Oden findings with respect to particle sources over the central Arctic. Future more frequent broken-ice or open water patches in summer will spur biological activity in surface water promoting the formation of biological particles. Thereby low clouds and fogs and subsequently the surface energy balance and ice melt may be affected.

Sea Ice Problems in Bohai Bay Oil and Gas Exploitation

ABSTRACT Zhang, D.; Xu, N.; Yue, Q., and Liu, D., 2015. Sea ice problems in Bohai Bay oil and gas exploitation. Sea ice infests the Bohai Bay every winter. Normally, ice condition is slight but sometimes heavy ice conditions may occur. It has been difficult for offshore designers to determine the conditions and the ice loads. Two jackets were pushed over by ice and others were designed too conservative as ice load were overestimated. In recent years some of the platforms have met severe ice induced vibrations, which has caused harmful accidents. In this paper, sea ice problems in oil and gas exploitation of Bohai Bay are briefly introduced. The dynamic behavior of ice resistant jacket structures and the potential failure modes that arise from cyclic ice actions are described.

Multiyear ice replenishment in the Canadian Arctic Archipelago: 1997–2013

AbstractIn the Canadian Arctic Archipelago (CAA), multiyear ice (MYI) replenishment from first‐year ice aging (CAAMYI‐Oct‐1) and Arctic Ocean MYI exchange (CAAMYI‐exchange) contribute to the CAA's relatively heavy sea ice conditions at the end of the summer melt season. We estimate these components using RADARSAT and the Canadian Ice Service Digital Archive and explore processes responsible for interannual variability from 1997 to 2013. CAAMYI‐Oct‐1 (52 ± 36 × 103 km2) provides a larger contribution than CAAMYI‐exchange (13 ± 11 × 103 km2). CAAMYI‐Oct‐1 represents ∼10% of the amount that occurs in the Arctic Ocean. CAAMYI‐exchange represents ∼50% of Nares Strait MYI export to Baffin Bay and ∼12% of Fram Strait MYI export to the Greenland Sea. CAAMYI‐Oct‐1 exhibits dependence on warmer (cooler) summers that increase (decrease) melt evident from strong relationships to surface air temperature (SAT), albedo and total absorbed solar radiation (Qtotal). CAAMYI‐exchange is influenced by summer sea level pressure (SLP) anomalies over the Beaufort Sea and Canadian Basin which shifts the primary source of CAAMYI‐exchange between less obstructed M'Clure Strait (low SLP anomalies) and the more obstructed Queen Elizabeth Islands (high SLP anomalies). Over the 17‐record, appreciable replenishment occurred for most years from 1997 to 2004, reduced replenishment from 2005 to 2012, and large replenishment in 2013. The reduced replenishment period was associated with positive SAT, negative albedo, and positive Qtotal anomalies that facilitated more melt and less CAAMYI‐Oct‐1, together with high SLP anomalies that facilitated less CAAMYI‐exchange. Large replenishment in 2013 was primarily from CAAMYI‐Oct‐1 attributed to strongly negative SAT and Qtotal anomalies and strongly positive albedo that impeded melt.