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Sea ice edges play an essential role in the Earth's climate and weather systems through active atmosphere‐ice‐ocean interactions. However, our understanding of the observed positions of sea ice edges remains limited. The present study investigated, on seasonal and longer timescales from 1979 to 2023, the variability in sea ice edge positions in the Barents and Greenland Seas. We objectively derived the positions of sea ice edges based on satellite‐derived sea ice concentration gridded on a 25‐km resolution. In the Barents Sea, warm, narrow currents flow eastward along the northern and southern rims of the Central Bank. Until the mid‐2000s, sea ice edges fluctuated between these currents interannually during December–June, depending on the surface wind direction. However, after the mid‐2000s, the sea ice edges were mostly positioned near the northern current or farther to the north. Furthermore, sea ice edges during October–March were identified frequently near the warm current flowing along the continental slope in the northern Barents Sea after the mid‐2000s. In the Greenland Sea, sea ice edges were typically positioned near the East Greenland Current (EGC) throughout the year until 2006. However, sea ice edges in summer were located far to the west of the EGC after 2006. These observations suggest that the geographical relationship between sea ice edges and ocean currents has changed due to global warming. Plain Language Summary: Sea ice edges in the Arctic play an important role in the Earth's climate system. They can strengthen atmospheric cyclones and vertical motion in the atmosphere and the ocean in the Arctic by inducing intense heat and moisture releases from the ocean to the atmosphere. Furthermore, they could exert distinct impacts on global‐scale atmosphere and ocean circulations. Therefore, a deeper understanding of the geographical positions of sea ice edges is essential for elucidating the climate system. This study investigated the sea ice edge positions in the Barents and Greenland Seas using satellite observations from 1979 to 2023. Sea ice edges rapidly advance southward during winter. Until the mid‐2000s, sea ice edges were frequently identified along warm ocean currents in the Barents and Greenland Seas because warm currents obstruct further sea ice edge advances. However, sea ice edges have shifted far to the north of warm ocean currents after the mid‐2000s in association with the recent shrinking in sea ice extent due to global warming. The change in sea ice edge positions might have affected the atmosphere and ocean circulations globally, which should be addressed in future studies. Key Points: In the central Barents Sea, sea ice edge positions fluctuated in winter until the mid‐2000s but have lately fixed along a warm currentSince the mid‐2000s, sea ice edges have been frequently identified along the continental slope in the northern Barents Sea in winterUntil 2006, sea ice edges in the Greenland Sea were located at the East Greenland Current, but they shifted far west after 2006 in summer [ABSTRACT FROM AUTHOR]

The seasonally ice-covered marine region of the European Arctic has experienced warming and sea ice loss in the last two decades. During expeditions in August 2020 and 2021, new data on size-fractioned primary production (PP), chlorophyll a concentration, phytoplankton biomass and composition and carbon fixation rates in the dark were obtained in the marginal ice zone (MIZ) of the Barents Sea, Nansen Basin and Greenland Sea to better understand the response of Arctic ecosystems to ongoing climate changes. Four different situations were observed in the study region: (i) a bloom of the large-cell diatom Podosira glacialis, whose biomass was trapped in a strong halocline at the edge of a dense ice cover; (ii) a bloom of the chain-like colonies of Thalassiosira diatoms on the shelf in mixed waters in fields of shallow ice that could be supported by "fresh" elements in the polynya condition, as well as by terrestrial run-off and drifting ices; at the late stage, this bloom was accompanied by intensive growth of Phaeocystis pouchetti; (iii) dominance of small-cell phytoplankton under weakened stratification and the significant influence of the Atlantic water, depleted of microelements and silicates; (iv) dominance of dinoflagellates of eutrophic water in the contact zone between the water masses of Arctic origin and Atlantic origin in clear water under conditions of increased light intensity. The >10 µm phytoplankton cell size group increased its relative contribution to PP as a response to stratification, light and nutrient load associated with sea ice conditions. Small phytoplankton with sizes < 2 µm formed the basis of total PP in the MIZ regardless of the state of the sea ice. [ABSTRACT FROM AUTHOR]

Here we investigate properties of ocean eddies in the key Arctic region of the northern Greenland Sea and the Fram Strait using visible and infrared Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua data acquired from April to September in 2007 and 2018–2020. We infer eddy properties using visual identification and automated processing of their signatures in sea surface temperature (SST) and chlorophyll-a (chl-a) maps, and their gradients. Altogether, 450 (721) eddies were identified in SST (chl-a) data. Their radii span from 2 to 40 km (mean value 12 km). Most eddies are elliptical with a mean aspect ratio (eccentricity) of their axes equal 0.77 (0.64). Cyclones are smaller than anticyclones and prevail in both data sources. Cyclones tend to be more prevalent over shallow shelves, and anticyclones over deep water regions. Peak eddy activity is registered in June, while chl-a data also possess a second peak in April. In SST, the highest eddy probability is found along the East Greenland Current in the Nordbukta region at 76–78°N and along the West Spitsbergen Current at 78–80°N. In chl-a, most of them are observed in the central Fram Strait. The overall number of eddies with a positive chl-a anomaly, dominated by cyclones, is larger (62%) than that with a negative one (~38%). The number of eddies with positive and negative SST anomalies is nearly equal. Eddy translation velocities are 0.9–9.6 km/day (mean value 4.2 km/day). Despite frequent cloud and ice cover, MODIS data is a rich source of information on eddy generation hot-spots, their spatial properties, dynamics and associated SST and chl-a anomalies in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Arctic sea ice outflow to the Atlantic Ocean is essential to Arctic sea ice mass loss and the hydrographical and ecological environments in the Barents and Greenland Seas (BGS). In the context of the extremely positive Arctic Oscillation (AO) in January-March 2020, the impacts and feedback mechanisms on a seasonal scale of anomalies in Arctic sea ice outflow on winter-spring sea ice and other marine environmental conditions in the subsequent months until early summer in the BGS were investigated. The results reveal that the total sea ice area flux (SIAF) through the Fram Strait, the Svalbard-Franz Josef Land, and the Franz Josef Land-Novaya Zemlya passageways in January-March and June 2020 were higher than the 1988-2020 climatology, mainly through the Fram Strait (77.6 %). The interannual variability of this total SIAF was dominated by changes in ice motion speed (R = +0.86, P < 0.001). The relatively high ice speed along the Transpolar Drift in January-June 2020 was related to the positive phases of winter (JFM) AO and the winter-spring air pressure gradient across the western and eastern Arctic Ocean. The abnormally high Arctic sea ice outflow led to an increased sea ice area and thickness in the BGS, which has been observed since March 2020, especially in May-June. In this region, the April sea ice area was significantly negatively correlated with synchronous sea surface temperature (SST) as well as the lagging SST of 1-3 months. High sea ice area in spring (AMJ) 2020 also inhibited phytoplankton bloom, with an extremely low Chlorophyll-a concentration observed over the BGS in April. Therefore, this study suggests that winter-spring Arctic sea ice outflow can be considered as a predictor of changes in sea ice and other marine environmental conditions in the BGS in the subsequent months, at least until early summer. The results increase our understanding of the physical connection between the central Arctic Ocean and the peripheral seas. [ABSTRACT FROM AUTHOR]

The interannual changes in ice coverage in the Greenland Sea for the winter (December–April), spring (May– June), summer (July–September), and autumn (October–November) seasons for the period 1950-2018 are considered. The presence of negative linear trends and the polycyclic oscillations of the ice coverage variability for all seasons has been confirmed. Using spectral analysis, the dominant fluctuations from 5 to 22 years were identified. The cross-correlation method allowed us to determine the significant relationship of the Greenland Sea ice coverage with hydrometeorological and astrogeophysical factors. The statistically significant relationship of the ice coverage for a concrete year with similar characteristics for a previous period persisting up to three years had been noted. The highest cross-correlation coefficients were noted in the winter and spring seasons. The ice coverage of the autumn season demonstrates the persistence of the inertia of ice conditions for up to two years. The analysis of correlations with astrogeophysical parameters revealed the closest relationship between the ice coverage and the longitude coordinate of the Earth's pole position, the nutation parameters of the Earth's axis, and the distance between the Earth and the Sun. When constructing the multi-regression equations, we investigated the informativeness of various hydrometeorological and astrogeophysical factors in the models of the ice coverage variability for each season. The following estimates of quality of the models were obtained: correlation coefficients (up to 0.89), determination coefficients (to up 0.80), and a model reliability which depends on the admissible forecast error and includes the mean square deviation of the investigated value) – up to 99%). The informativeness of various factors was estimated and the contribution to the total variance was revealed: hydrometeorological factors – up to 70%; astrogeophysical factors – up to 50%. The obtained statistical equations can be used for the diagnosis and for development of methods for the very-long-term forecast of the Greenland Sea ice coverage.

• Variability in stratification is resolved on seasonal and decadal time scales. • The upper Greenland Sea became consistently temperature-dominated in summers after 1997. • The intermediate Greenland Sea switched from haline to thermal stratification in the 1990's. • Jointly, the changes in stratification indicate Atlantification of the Greenland Sea. Stratification and its thermal and haline contributions are important ocean properties of fundamental climatic influence. Upper-ocean stratification shapes marine ecosystems by regulating nutrient availability and deep-ocean stratification is important for carbon sequestration and ventilating the ocean interior. Here, we first assess the applicability of an ocean reanalysis product in representing stratification in the Nordic Seas and East Greenland Shelf. While the reanalysis performs well in most interior basins, it exhibits significant shortcomings on the East Greenland shelf, raising concerns about the reanalysis product in these areas. We then examine the development in the thermal and haline contributions to summer upper- (100 m) and winter intermediate- (1000 m) ocean stratification in the Greenland Sea from 1980 to 2020. We find that there has been a transition in the controls of winter stratification in the upper 1000 m of the Greenland Sea. The transition was associated with a westward migration of the boundary between salinity- and temperature-stratified waters and eventual switch from haline to thermal control of winter stratification. With that follows a change in the type of forcing that can lead to convection: The Greenland Sea is now less dependent on eroding salinity gradients but rather depends on cooling to overcome stratification. There has been a similar switch in summer stratification in the upper-ocean of the Greenland Sea where surface waters shifted from variable stratification, alternating between salinity and temperature dominance, to a stable temperature-stratified regime. This switch coincided with declining sea-ice concentrations related to the disappearance of the Odden ice tongue after 1997. The high sea-ice conditions previously characteristic of the Greenland Sea are now rare suggesting the transition will persist with potential implications for marine ecology and local sea-ice formation. Our findings reveal differences in how thermal and haline stratification has developed over the last 40 years, which may help explain or predict plankton production and carbon uptake and export. [ABSTRACT FROM AUTHOR]

The results of studies of seasonal and inter-annual variability of the Greenland Sea ice cover are presented for the period from 1950 to 2016. Statistical characteristics of seasonal and inter-annual changes in the ice-covered area were calculated. Three clusters of typical seasonal variability were identified from the whole totality of all seasonal cycles. The first cluster presented a group of seasonal cycles in the period of maximum, the second one – the middle, and the third group – minimum areas of the winter ice cover. The estimates of correlation between changes in the ice areas in winter (February–March) or in summer (August–September) and areas of the following two months of a current year as well as in succeeding years were obtained. Empirical regularity of a variability of the ice cover during the annual cycle was established. This regularity is characterized by an existence of a ‘memory’ in the state of the ice cover, when a prehistory of the ice conditions determines to a certain extent the following phase. Analysis of inter-annual variability of the Greenland Sea ice cover did show a linear negative tendency in both winter and summer ice conditions. One-two year fluctuations were the most pronounced in the spectral density of inter-annual variations in the summer ice conditions. However, fluctuations with a longer period do also exist. With respect to contribution of hydrometeorological factors, the summer ice area is determined: (a) by conditions in the preceding winter, (b) by the atmospheric circulation, and (c) by the influence of warm Atlantic waters (about 20% of the total dispersion). Changes in the winter ice area depend: (a) mainly on the pre-winter state of ices (October–November), (b) on the influence of the Atlantic waters (about 30% of the total dispersion), and (c) on the heat balance and the atmospheric circulation (20% of the total dispersion). The results of this study may be used as a basis for the development of statistical models for analysis and prediction of long-term and climatic changes in the state of the ice cover in the Greenland Sea.

Climate model projections suggest a substantial decrease of sea ice export into the outflow areas of the Arctic Ocean over the 21st century. Fram Strait, located in the Greenland Sea sector, is the principal gateway for ice export from the Arctic Ocean. The consequences of lower sea ice flux through Fram Strait on ocean dynamics and primary production in the Greenland Sea remain unknown. By using the most recent 16 years (2003–2018) of satellite imagery available and hydrographic in situ observations, the role of exported Arctic sea ice on water column stratification and phytoplankton production in the Greenland Sea is evaluated. Years with high Arctic sea ice flux through Fram Strait resulted in high sea ice concentration in the Greenland Sea, stronger water column stratification, and an earlier spring phytoplankton bloom associated with high primary production levels. Similarly, years with low Fram Strait ice flux were associated with a weak water column stratification and a delayed phytoplankton spring bloom. This work emphasizes that sea ice and phytoplankton production in subarctic "outflow seas" can be strongly influenced by changes occurring in the Arctic Ocean. Plain Language Summary: As the Arctic atmosphere and ocean warm, Arctic sea ice continues to decline. The Greenland Sea (to the east of Greenland) is heavily influenced by sea ice leaving the Arctic Ocean. In this study, we address the impacts of sea ice exiting the Arctic on the development of free‐floating microscopic algae in the Greenland Sea. For this, we analyzed 16 years of data from satellite images and autonomous ocean robots. Our results reveal that changes in the quantity of sea ice leaving the Arctic Ocean in spring modify the environment and development of microscopic algae. These algae are important because they capture carbon dioxide and support ocean life; this paper can help to predict how they will respond to the ongoing environmental changes occurring in the Arctic. Key Points: A positive relationship exists between exported Arctic sea ice and the sea ice distribution in the Greenland SeaHigh (low) springtime export of Arctic sea ice may increase (reduce) the stratification of the Greenland BasinA strong (weak) salinity stratification of the Greenland Basin induces an early (late) phytoplankton spring bloom and primary production [ABSTRACT FROM AUTHOR]

Substantial changes have occurred in the Arctic Ocean in the last decades. Not only sea ice has retreated significantly, but also the ocean at middepth showed a warming tendency. By using simulations we identified a mechanism that intensifies the upward trend in ocean heat supply to the Arctic Ocean through Fram Strait. The reduction in sea ice export through Fram Strait induced by Arctic sea ice decline increases the salinity in the Greenland Sea, which lowers the sea surface height and strengthens the cyclonic gyre circulation in the Nordic Seas. The Atlantic Water volume transport to the Nordic Seas and Arctic Ocean is consequently strengthened. This enhances the warming trend of the Arctic Atlantic Water layer, potentially contributing to the Arctic "Atlantification." Our study suggests that the Nordic Seas can play the role of a switchyard to influence the heat budget of the Arctic Ocean. Plain Language Summary: The Arctic sea ice decline is among the key indications of climate change, which has strong impacts on the environment, human beings, and biodiversity. In this paper we found that the Arctic sea ice decline at the surface can even cause Arctic Ocean warming at middepth by intensifying the upward trend of ocean heat supply to the Arctic Ocean through Fram Strait. The Nordic Seas play the role of a switchyard for the involved processes: The sea ice decline reduces the sea ice export through Fram Strait, which further increases the salinity in the Greenland Sea. Consequently, in the Nordic Seas the sea surface height decreases and the gyre circulation strengthens. These changes then increase the Atlantic Water inflow to the Nordic Seas and the Arctic Ocean, causing significant warming in the Atlantic Water layer of the Arctic Ocean. The changes in the ocean heat budget have strong implications on potential feedbacks to sea ice decline through basal melting in a future warming climate. The intensification of the Atlantic Water volume transport through Fram Strait can impact not only the Arctic heat budget but also potentially the nutrient budget and the primary production. Key Points: The decline of Arctic sea ice reduces its export, thus increasing the salinity in Greenland SeaThis reduces the sea surface height and speeds up the gyre circulation in Greenland and Nordic SeasThe consequently enhanced Atlantic Water transport intensifies the warming at Fram Strait and in the Arctic Ocean [ABSTRACT FROM AUTHOR]

The gyres of the Iceland and Greenland Seas are regions of deep-water formation, driven by large ocean-to-atmosphere heat fluxes that have local maxima adjacent to the sea-ice edge. Recently these regions have experienced a dramatic loss of sea ice, including in winter, which begs the question have surface heat fluxes in the adjacent ocean gyres been affected? To address this a set of regional atmospheric climate model simulations has been run with prescribed sea ice and sea surface temperature fields. Three 20-year model experiments have been examined: Icemax, Icemed and Icemin, where the surface fields are set as the year with maximum, median and minimum sea-ice extents respectively. Under conditions of reduced sea-ice extent there is a 15% (19 W m−2) decrease in total wintertime heat fluxes in the Iceland Sea. In contrast, there is an 8% (9 W m−2) increase in heat fluxes in the Greenland Sea primarily due to higher local SSTs. These differences are manifest as changes in the magnitude of high heat flux events (such as cold air outbreaks). In the Iceland Sea, 76% of these events are lower in magnitude during reduced sea-ice conditions. In the Greenland Sea, 93% of these events are higher in magnitude during reduced sea-ice conditions as a result of higher SSTs coincident with retreating sea ice. So, in these experiments, the reduced wintertime sea-ice conditions force a different response in the two seas. In both gyres, large-scale atmospheric circulation patterns are key drivers of high heat flux events. [ABSTRACT FROM AUTHOR]

Multimodel Arctic Ocean "climate response function" experiments are analyzed in order to explore the effects of anomalous wind forcing over the Greenland Sea (GS) on poleward ocean heat transport, Atlantic Water (AW) pathways, and the extent of Arctic sea ice. Particular emphasis is placed on the sensitivity of the AW circulation to anomalously strong or weak GS winds in relation to natural variability, the latter manifested as part of the North Atlantic Oscillation. We find that anomalously strong (weak) GS wind forcing, comparable in strength to a strong positive (negative) North Atlantic Oscillation index, results in an intensification (weakening) of the poleward AW flow, extending from south of the North Atlantic Subpolar Gyre, through the Nordic Seas, and all the way into the Canadian Basin. Reconstructions made utilizing the calculated climate response functions explain ∼50% of the simulated AW flow variance; this is the proportion of variability that can be explained by GS wind forcing. In the Barents and Kara Seas, there is a clear relationship between the wind‐driven anomalous AW inflow and the sea ice extent. Most of the anomalous AW heat is lost to the atmosphere, and loss of sea ice in the Barents Sea results in even more heat loss to the atmosphere, and thus effective ocean cooling. Release of passive tracers in a subset of the suite of models reveals differences in circulation patterns and shows that the flow of AW in the Arctic Ocean is highly dependent on the wind stress in the Nordic Seas. Plain Language Summary: The North Atlantic Current is an extension of the Gulf Stream, which brings warm Atlantic Water northward as the current flows through the Nordic Seas. Eventually, it enters the cold deep Arctic Ocean basins through the Barents Sea and Fram Strait. Nine different numerical ocean ice models have been analyzed and compared in order to investigate (1) their ability to simulate this northward flow of Atlantic Water, (2) its dependence on wind forcing, and (3) its impact on Arctic sea ice. Consistently, in all models, stronger winds in the Greenland Sea result in a stronger northward flow of warm Atlantic Water. The response on ocean circulation occurs from the North Atlantic, through the Nordic Seas and the Barents Sea, to the deep Canadian Basin. The flow of warm Atlantic Water within the Arctic Ocean is thus highly dependent on the wind stress in the Nordic Seas. There is particularly clear response in the Barents and Kara Seas where a wind‐driven anomalous warm inflow drives a smaller sea ice extent and thickness, and an increased heat transfer from the ocean to the atmosphere above. Weaker winds in the Greenland Sea produces weaker flow and hence a larger sea ice extent and thickness. Key Points: Stronger/weaker winds over the Greenland Sea result in stronger/weaker flow of Atlantic Water in the Nordic Seas and into the Arctic OceanIn the Barents Sea there is a linear relationship between Atlantic Water volume and heat transport, surface heat loss, and sea ice extentThere is potential for predictability of the Arctic‐Atlantic circulation based on wind forcing anomalies and climate response functions [ABSTRACT FROM AUTHOR]

In seasonal ice zones (SIZs), such as the one of the Greenland Sea, the sea ice growth in winter and subsequent melting in summer influence the phytoplankton activity. However, studies assessing phytoplankton activities over complete annual cycles and at a fine temporal resolution are lacking in this environment. Biogeochemical‐Argo floats, which are able to sample under the ice, were used to collect physical and biogeochemical data along vertical profiles and at 5‐day resolution during two complete annual cycles in the Greenland Sea SIZ. Three phytoplankton activity phases were distinct within an annual cycle: one under ice, a second at the ice edge, and a third one around an open‐water subsurface chlorophyll maximum. As expected, the light and nitrate availabilities controlled the phytoplankton activity and the establishment of these phases. On average, most of the annual net community production occurred equally under ice and at the ice edge. The open‐water subsurface chlorophyll maximum phase contribution, on the other hand, was much smaller. Phytoplankton biomass accumulation and production thus occur over a longer period than might be assumed if under ice blooms were neglected. This also means that satellite‐based estimates of phytoplankton biomass and production in this SIZ are likely underestimated. Simulations with the Arctic‐based physical‐biologically coupled SINMOD model suggest that most of the annual net community production in this SIZ results from local processes rather than due to advection of nitrate from the East Greenland and Jan Mayen Currents. Key Points: In the seasonal ice zone, significant phytoplankton activity occurs under ice earlier in the seasonAt the ice edge, a high phytoplankton biomass is present around a subsurface chlorophyll maximum feature that persists into summerHalf of the annual Net Community Production occurs under ice and the other half at the ice edge [ABSTRACT FROM AUTHOR]

Liu, X. and Zhang, L., 2018. Study on optimization of sea ice concentration with adjoint method. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 44–50. Coconut Creek (Florida), ISSN 0749-0208. Obtaining initial sea ice concentration (SIC) values with high accuracy that are consistent with other models have been a hot topic in both sea ice prediction and sea ice modeling studies. Here, an ocean-sea ice coupled numerical model and its adjoint code have been utilized to carry out numerical experiments to optimize the initial SIC values. In the experiments, the cost function was defined as the difference between the SIC values from the reanalysis dataset and the modeled results. The gradient of cost function, relative to SIC and other model variables, was computed by the adjoint model, and a linear search algorithm was employed to optimize the SIC values by minimizing the cost function. The influences of the weight coefficients of the cost function, the extent of the geographical region, and the seawater temperature and sea ice thickness initial values on the optimization results have been analyzed. The weight coefficients of the cost function had little effect on the SIC distribution pattern but substantial influence on the SIC values. The optimized SIC in the Greenland Sea, Okhotsk Sea, and the Arctic Ocean, with a constant weight coefficient, is better than that with variable weight coefficients. The errors in the initial model fields, other than SIC, may deteriorate the overall result, implying that optimizing multiple model fields simultaneously may improve the optimization effect. Decreasing the size of the geographical region for optimization does not improve the SIC optimization results substantially. Compared to the results from a global cost function, the Barents Sea SIC values from a northern hemispheric cost function are poorly optimized. [ABSTRACT FROM AUTHOR]

The sea-to-air flux of dimethylsulphide (DMS) is one of the major sources of marine biogenic aerosol, and can have an important radiative impact on climate, especially in the Arctic Ocean. Satellite-derived aerosol optical depth (AOD) is used as a proxy for aerosol burden which is dominated by biogenic aerosol during summer and autumn. The spring sea ice melt period is a strong source of aerosol precursors in the Arctic. However, high aerosol levels in early spring are likely related to advection of continental pollution from the south (Arctic haze). Higher AOD was generally registered in the southern part of the study region. Sea ice concentration (SIC) and AOD were positively correlated, while cloud cover (CLD) and AOD were negative correlation. The seasonal peaks of SIC and CLD were both one month ahead of the peak in AOD. There is a strong positive correlation between AOD and SIC. Melting ice is positively correlated with chlorophyll a (CHL) almost through March to September, but negatively correlated with AOD in spring and early summer. Elevated spring and early summer AOD most likely were influenced by combination of melting ice and higher spring wind in the region. The peak of DMS flux occurred in spring due to the elevated spring wind and more melting ice. DMS concentration and AOD were positively correlated with melting ice from March to May. Elevated AOD in early autumn was likely related to the emission of biogenic aerosols associated with phytoplankton synthesis of DMS. The DMS flux would increase more than triple by 2100 in the Greenland Sea. The significant increase of biogenic aerosols could offset the warming in the Greenland Sea. [ABSTRACT FROM AUTHOR]

Open water areas surrounded by sea ice significantly influence the ocean-ice-atmosphere interaction and contribute to Arctic climate change. Satellite altimetry can detect these ice openings and enables one to estimate sea surface heights and further altimetry data derived products. This study introduces an innovative, unsupervised classification approach for detecting open water areas in the Greenland Sea based on high-frequency data from Envisat and SARAL. Altimetry radar echoes, also called waveforms, are analyzed regarding different surface conditions. Six waveform features are defined to cluster radar echoes into different groups indicating open water and sea ice waveforms. Therefore, the partitional clustering algorithm K-medoids and the memory-based classification method K-nearest neighbor are employed, yielding an internal misclassification error of about 2%. A quantitative comparison with several SAR images reveals a consistency rate of 76.9% for SARAL and 70.7% for Envisat. These numbers strongly depend on the quality of the SAR images and the time lag between the measurements of both techniques. For a few examples, a consistency rate of more than 90% and a true water detection rate of 94% can be demonstrated. The innovative classification procedure can be used to detect water areas with different spatial extents and can be applied to all available pulse-limited altimetry datasets. [ABSTRACT FROM AUTHOR]

This study presents a comparison of the sea-ice cover of the whole Arctic Ocean with two arctic sectors of different morphology: the Greenland Sea, as a typical “open sea”, and the Beaufort Sea, as a typical “closed sea”. The study refers to the period January 1996–December 2015 and makes use of the Arctic sea-ice concentration data set produced, on a daily basis, by the Institute of Environmental Physics of the University of Bremen. From the whole Arctic data set, two subsets, covering the Greenland Sea and the Beaufort Sea, were extracted. The extent of sea-ice cover was obtained by the sea-ice area (SIA) parameter, which was computed according to the conventional NASA method. Our analysis shows that the strong summer decline of the Arctic SIA in the last 20 years is not observed in the Greenland Sea (the trend of SIA minimum values is) while it is even greater in the Beaufort Sea. [ABSTRACT FROM PUBLISHER]

Microplastics have been reported everywhere around the globe. With very limited human activities, the Arctic is distant from major sources of microplastics. However, microplastic ingestions have been found in several Arctic marine predators, confirming their presence in this region. Nonetheless, existing information for this area remains scarce, thus there is an urgent need to quantify the contamination of Arctic marine waters. In this context, we studied microplastic abundance and composition within the zooplankton community off East Greenland. For the same area, we concurrently evaluated microplastic contamination of little auks ( Alle alle ), an Arctic seabird feeding on zooplankton while diving between 0 and 50 m. The study took place off East Greenland in July 2005 and 2014, under strongly contrasted sea-ice conditions. Among all samples, 97.2% of the debris found were filaments. Despite the remoteness of our study area, microplastic abundances were comparable to those of other oceans, with 0.99 ± 0.62 m −3 in the presence of sea-ice (2005), and 2.38 ± 1.11 m −3 in the nearby absence of sea-ice (2014). Microplastic rise between 2005 and 2014 might be linked to an increase in plastic production worldwide or to lower sea-ice extents in 2014, as sea-ice can represent a sink for microplastic particles, which are subsequently released to the water column upon melting. Crucially, all birds had eaten plastic filaments, and they collected high levels of microplastics compared to background levels with 9.99 and 8.99 pieces per chick meal in 2005 and 2014, respectively. Importantly, we also demonstrated that little auks took more often light colored microplastics, rather than darker ones, strongly suggesting an active contamination with birds mistaking microplastics for their natural prey. Overall, our study stresses the great vulnerability of Arctic marine species to microplastic pollution in a warming Arctic, where sea-ice melting is expected to release vast volumes of trapped debris. [ABSTRACT FROM AUTHOR]

Field experimental data from a 1980s program in the Greenland Sea investigating the evolution of directional wave spectra in the marginal ice zone are reanalyzed and compared with the predictions of a new, phase-resolving, three-dimensional model describing the two-dimensional scattering of the waves by the vast number of ice floes that are normally present. The model is augmented with a dissipative term to account for the nonconservative processes affecting wave propagation. Observations reported in the experimental study are used to reproduce the ice conditions and wave forcing during the experiments. It is found that scattering alone underestimates the attenuation experienced by the waves during their passage through the ice field. With dissipation, however, the model can replicate the observed attenuation for most frequencies in the swell regime. Model predictions and observations of directional spreading are in agreement for short to midrange wave periods, where the wave field quickly becomes isotropic. For larger wave periods, little spreading can be seen in the model predictions, in contrast to the isotropic or near-isotropic seas reported in the experimental study. The discrepancy is conjectured to be a consequence of the inaccurate characterization of the ice conditions in the model and experimental errors. [ABSTRACT FROM AUTHOR]

Drifting icebergs and sea ice floes can be serious threats to offshore structures in the Arctic; however, information about their drift is limited. We performed GPS tracking of 9 icebergs and 10 ice floes in the Kanumas area of the Greenland Sea during 2012–2014. The obtained coordinates were used to analyse the drift trajectories, derived velocities, spectra and relative drift of the icebergs and sea ice. This paper presents statistical data on the drift velocities and demonstrates the differences between drifts in the shear ice zone and the central pack or marginal ice zone. The maximum drift speed reached by an iceberg was 1.66 m/s, which happened during strong southerly wind at 66°N. The relative drift of icebergs and adjacent sea ice is strongly dependent on ice conditions and wind, but also it is determined by the different types of applied drag forces. Then, spectral analysis revealed that GPS errors may prevent capturing processes faster than one cycle per hour. In addition, for the first time, we measured the rotation of four icebergs around their vertical axes. Icebergs make an average of between one and two revolutions per day under the periodic tidal current. However, the instantaneous angular velocity reached 0.001 rad/s at some moments. Finally, this paper proposes an iceberg drift model including the rotation. The modelling results are in good agreement with the measured evolution of the icebergs’ yaw angles. The drift data and the rotation model can be used when planning offshore activities in the area or as an input for numerical models involving sea ice. [ABSTRACT FROM AUTHOR]

Over the past decade, the diminishing Arctic sea ice has impacted the wave field which is principally dependent on the ice-free area and wind. This study characterizes the wave climate in the Arctic using detailed sea state information from a wave hindcast and merged altimeter dataset spanning 1992-2014. The wave model uses winds from the Climate Forecast System Reanalysis and ice concentrations derived from satellites as input. The ice concentrations have a grid spacing of 12.5 km, which is sufficiently able to resolve important features in the marginal ice zone. The model performs well, verified by the altimeters and is relatively consistent for climate studies. The wave seasonality and extremes are linked to the ice coverage, wind strength, and wind direction. This creates distinct features in the wind-seas and swells. The increase in wave heights is caused by the loss of sea ice and not the wind verified by the altimeters and model. However, trends are convoluted by inter-annual climate oscillations like the North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation. The Nordic-Greenland Sea is the only region with negative trends in wind speed and wave height and is related to the NAO. Swells are becoming more prevalent and wind-sea steepness is declining which make the impact on sea ice uncertain. It is inconclusive how important wave-ice processes are within the climate system, but selected events suggest the importance of waves within the marginal ice zone. [ABSTRACT FROM AUTHOR]

Arctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only affect local sea-ice formation, but also control the sea-ice transport from the Arctic Ocean through a sea-ice–ocean–atmosphere feedback mechanism. The role of solar forcing, however, appears to have been more ambiguous during an interval around AD 1500, after the transition from the Medieval Climate Anomaly to the Little Ice Age, likely to be driven by a range of factors. [ABSTRACT FROM AUTHOR]

Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examine satellite-derived chlorophyll, aerosol and sea ice in the Greenland Sea. [•] There is a moderate correlation between chlorophyll and aerosol in ice-free waters. [•] We find no correlation between chlorophyll and sea ice. [•] Peaks in aerosol during summer succeed the peak in chlorophyll. [•] Marine biogenic aerosol emissions influence the aerosol burden during summer. [Copyright &y& Elsevier]

The Arctic Ocean (AO) has experienced very significant warming in recent decades with clear impacts on the extent and depth of sea ice cover. Sea ice serves as a primary habitat and plays an important role in the AO marine food web. The surface distributions of chlorophyll_ a (CHL), sea ice concentration (ICE), sea surface temperature (SST) and North Atlantic Oscillation (NAO) are analyzed in the study region (20°W-50°E, 70°N-80°N) over the decade (2003–2014). This region spans the Barents Sea (BS), Norwegian (NS) and Greenland Sea (GS). In general, the peak of spatial averaged CHL in the BS was about 60% higher than the GS. Due to elevated SST in the southern BS, CHL was much higher especially in 2010 and 2013. In 2011, there was a strong meridional gradient in CHL decreasing from south to north of the BS, and also a strong zonal gradient from the southern GS to the southern BS. The northern GS had higher CHL than the southern GS due to the increased ice melting and nutrient-enriched runoff from east Greenland glaciers to the northern and western coastal regions of the GS. Seasonal peaks of spatially averaged CHL occurred in April or May and were about two weeks earlier in the BS than the GS. Higher ice melt in the northern BS was the main reason for CHL blooms especially in 2010 and 2011. Earlier and more extensive ice melting and a persistent negative NAO index causing atmospheric circulation patterns that favoured ice loss were the possible drivers of enhanced phytoplankton blooms in 2010. A previous negative winter NAO is thought to be linked to an increase in ICE in the following spring. NAO is mostly negative during spring in the GS. Sea ice melt was positively correlated with CHL in the northern sector of the study region. • Time series of chlorophyll and ice cover are studied in Greenland Sea and Barents Sea • Distributions of chlorophyll (CHL) and ice cover (ICE) are compared • BS (Barents Sea) had much higher CHL than GS (Greenland Sea), especially in year 2010 • The relationship between North Atlantic Oscillation (NAO) with CHL and ICE are studied • Negative NAO was associated with increasing ice melting in following spring and increased CHL in that year, especially in GS [ABSTRACT FROM AUTHOR]

The biomass of Calanus spp. in the Norwegian Atlantic Current and the West Spitsbergen Current (2001–2009) was statistically related to a combination of salinity, temperature, water depth and sea ice concentration. The aim of this study was to identify the significance of these environmental factors for controlling the species-specific biomass distribution and the nature of such relationships. Calanus finmarchicus dominated the entire area and its biomass was mainly related to salinity. Calanus glacialis was mainly found along the northwest shelf of the Barents Sea, but its biomass was also related to the sea ice concentration and temperature with a critical threshold ∼6°C, above which the presence and biomass of C. glacialis decreased. The Calanus hyperboreus biomass was related to all environmental factors, which characterized by a confined spatial distribution to water associated with the Greenland Sea Gyre. We conclude that C. hyperboreus is an expatriate to the study area. The Calanus biomass distribution will not change greatly in the study area with an expected increase of water temperature by 2°C, whereas the critical temperature threshold for C. glacialis will be exceeded with temperature increases of ∼4°C with a likely disappearance of this cold water species from the north-west shelf of the Barents Sea. [ABSTRACT FROM AUTHOR]

We review the development of autonomous underwater vehicle (AUV) use under sea ice to map the three-dimensional (3-D) structure of the ice underside. The author, after extensive experience in under-ice profiling from submarines using single-beam sonar, carried out the first under-ice sidescan sonar profiling from an AUV in 2002 in the Greenland Sea. This was followed in August 2004 by the first full multibeam sonar experiment, using Kongsberg EM2000 sonar aboard the Autosub-II vehicle off NE Greenland. Two experiments using a small Gavia vehicle deployed through holes in the ice followed in 2007 and 2008, in the Beaufort Sea and off Ellesmere Island. Examples of the 3-D imagery are shown, and the two approaches of using a large vehicle deployed from a ship and a small through-ice vehicle are compared and found to be complementary. The imagery has shown that although first-year (FY) ridges have the familiar shape of a triangular prism made of small ice blocks, multi-year (MY) ridges are found to be broken up by lead formation into a chain of individual large ice blocks rather than a coherent linear feature. New work and future plans are described. [ABSTRACT FROM AUTHOR]

ABSTRACT Annual air-sea exchange of CO2 in Young Sound, NE Greenland was estimated using pCO2 surface-water measurements during summer (2006-2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation, dissolved inorganic carbon (DIC) content is reduced causing sea ice to be under saturated in CO2. Approximately 1% of the DIC forced out of growing sea ice was released into the atmosphere while the remaining 99% was exported to the underlying water column. Sea ice covered the fjord 9 months a year and thereby efficiently blocked air-sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive carbonate minerals may contribute to the low surface-water pCO2 levels. The average annual uptake of atmospheric CO2 was estimated at 2.7 mol CO2 m−2 yr−1 or 32 g C m−2 yr−1 for the study area, which is lower than estimates from the Greenland Sea. Variability in duration of sea ice cover caused significant year-to-year variation in annual gas exchange. [ABSTRACT FROM AUTHOR]

The paper describes changes in winter gale day frequency that took place in the Shetland and Faeroe Isles between ca. AD 1866-1905. During the early part of this period, winter gale day frequencies reached values that have never been exceeded since. During the later part of this time interval, culminating in the winters of 1903-04 and 1904-05, scarcely any gales occurred. The majority of the time interval between 1866 -1895 was characterized by high-amplitude fluctuations in the sign of the North Atlantic Oscillation (NAO) index (extreme positive to extreme negative) and by extreme changes in annual sea ice extent across the Greenland Sea. Between 1866-1894, however, winter gale day frequencies remained consistently high. It is suggested that this unusual relationship may be explained through the important role of sea ice extent across the Greenland Sea affecting the extent of the polar anticyclone and hence the position of the North Atlantic storm track. By contrast, the later part of this time interval (AD 1894-1905) was characterized by very few winter gales and no extremes in the monthly NAO Index. [ABSTRACT FROM AUTHOR]

Feedback between the North Atlantic Oscillation (NAO) and winter sea ice variability is detected and quantified using approximately 30 years of observations, a vector autoregressive model (VAR), and testable definitions of Granger causality and feedback. Sea ice variability is quantified based on the leading empirical orthogonal function of sea ice concentration over the North Atlantic [the Greenland Sea ice dipole (GSD)], which, in its positive polarity, has anomalously high sea ice concentrations in the Labrador Sea region to the southwest of Greenland and low sea ice concentrations in the Barents Sea region to the northeast of Greenland. In weekly data for December through April, the VAR indicates that NAO index (N) anomalies cause like-signed anomalies of the standardized GSD index (G), and that G anomalies in turn cause oppositely signed anomalies of N. This negative feedback process operates explicitly on lags of up to four weeks in the VAR but can generate more persistent effects because of the autocorrelation of G. Synthetic data are generated with the VAR to quantify the effects of feedback following realistic local maxima of N and G, and also for sustained high values of G. Feedback can change the expected value of evolving system variables by as much as a half a standard deviation, and the relevance of these results to intraseasonal and interannual NAO and sea ice variability is discussed. [ABSTRACT FROM AUTHOR]

The minimum of Arctic sea ice extent in the summer of 2007 was unprecedented in the historical record. A coupled ice–ocean model is used to determine the state of the ice and ocean over the past 29 yr to investigate the causes of this ice extent minimum within a historical perspective. It is found that even though the 2007 ice extent was strongly anomalous, the loss in total ice mass was not. Rather, the 2007 ice mass loss is largely consistent with a steady decrease in ice thickness that began in 1987. Since then, the simulated mean September ice thickness within the Arctic Ocean has declined from 3.7 to 2.6 m at a rate of -0.57 m decade-1. Both the area coverage of thin ice at the beginning of the melt season and the total volume of ice lost in the summer have been steadily increasing. The combined impact of these two trends caused a large reduction in the September mean ice concentration in the Arctic Ocean. This created conditions during the summer of 2007 that allowed persistent winds to push the remaining ice from the Pacific side to the Atlantic side of the basin and more than usual into the Greenland Sea. This exposed large areas of open water, resulting in the record ice extent anomaly. [ABSTRACT FROM AUTHOR]

A preindustrial climate experiment was conducted with the third version of the CNRM global atmosphere–ocean–sea ice coupled model (CNRM-CM3) for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). This experiment is used to investigate the main physical processes involved in the variability of the North Atlantic ocean convection and the induced variability of the Atlantic meridional overturning circulation (MOC). Three ocean convection sites are simulated, in the Labrador, Irminger and Greenland–Iceland–Norwegian (GIN) Seas in agreement with observations. A mechanism linking the variability of the Arctic sea ice cover and convection in the GIN Seas is highlighted. Contrary to previous suggested mechanisms, in CNRM-CM3 the latter is not modulated by the variability of freshwater export through Fram Strait. Instead, the variability of convection is mainly driven by the variability of the sea ice edge position in the Greenland Sea. In this area, the surface freshwater balance is dominated by the freshwater input due to the melting of sea ice. The ice edge position is modulated either by northwestward geostrophic current anomalies or by an intensification of northerly winds. In the model, stronger than average northerly winds force simultaneous intense convective events in the Irminger and GIN Seas. Convection interacts with the thermohaline circulation on timescales of 5–10 years, which translates into MOC anomalies propagating southward from the convection sites. [ABSTRACT FROM AUTHOR]

In order to elucidate the seasonal and interannual variations of oceanic CO2 uptake in the Greenland Sea and the Barents Sea, the partial pressure of CO2 in the surface ocean ( pCO2sea) was measured in all seasons between 1992 and 2001. We derived monthly varying relationships between pCO2sea and sea surface temperature (SST) and combined them with the SST data from the NCEP/NCAR reanalysis to determine pCO2sea and air–sea CO2 flux in these seas. The pCO2sea values were normalized to the year 1995 by assuming that pCO2sea increased at the same growth rate (1.5 μatm yr−1) of the pCO2 in the air ( pCO2air) between 1992 and 2001. In 1995, the annual net air–sea CO2 fluxes were evaluated to be 52 ± 20 gC m−2 yr−1 in the Greenland Sea and 46 ± 18 gC m−2 yr−1 in the Barents Sea. The CO2 flux into the ocean reached its maximum in winter and minimum in summer. The wind speed and Δ pCO2 (= pCO2air– pCO2sea) exerted a greater influence on the seasonal variation than the sea ice coverage. The annual CO2 uptake examined in this study (70°–80°N, 20°W–40°E) was estimated to be 0.050 ± 0.020 GtCyr−1 in 1995. The interannual variation in the annual CO2 uptake was found to be positively correlated with the North Atlantic Oscillation Index (NAOI) via wind strength but negatively correlated with Δ pCO2 and the sea ice coverage. The present results indicate that the variability in wind speed and sea ice coverage play a major role, while that in Δ pCO2 plays a minor role, in determining the interannual variation of CO2 uptake in this area. [ABSTRACT FROM AUTHOR]

Abstract: In the ice covered waters of the Greenland Sea the polarisation ratio of QuikSCAT SeaWinds Ku-band (13.4 GHz) scatterometer measurements and the polarisation ratio of DMSP-SSM/I 19 GHz radiometer measurements are used in combination to classify new-ice and mature ice. In particular, the formation of the new-(frazil/pancake)-ice ‘Odden’ (8° W, 75° N) March 11th–18th, 2001, is used in the study. The results of the ice cover classification in the Greenland Sea are compared to model parameters from a sea ice model. The classification of each ice pixel is performed using its backscatter and radiative properties as reflected in the polarisation ratio. Our results based on these comparisons show that the transformation into older mature (sheet) ice occurs within 5–10 days. During one day the new-ice cover increased by 33000 km2. The new-ice appears in March 2001 as a peninsula (maximum extent 56000 km2) appended to the belt of older ice drifting along the East Coast of Greenland. These results are consistent with the ice model and with Radarsat images. Furthermore, using the ice model it is demonstrated that the new-ice/mature ice threshold in the classification corresponds to the physical transition of the ice cover from pancake ice to a consolidated young-ice sheet. The classification of each pixel into ice or water is done using two scatterometer parameters, namely the polarisation ratio and the daily standard deviation of the backscatter. [Copyright &y& Elsevier]

Variations in the extent of sea ice within the Greenland Sea on daily, seasonal, or longer time scales are well documented, while changes in ice conditions are not. By combining historical information on the location and timing of the hunt for the whelping harp seal (Phoca groenlandica) with the ice conditions needed for the seals to give birth, details of the types, concentration, and extent of ice within the central Greenland Sea in winter have been determined for the mid- to late nineteenth century. These in turn have been compared to ice extent and concentration from the passive microwave era, as well as ice types from field work in the region. Results suggest that the ice conditions in the central Greenland Sea in the mid- to late nineteenth century were significantly different from those witnessed in recent decades. These differences manifest themselves not only in the extent of ice, but in ice types, concentration, and longevity of the ice cover. It is hypothesized that these changes could be due to an increase in both air temperature and wave energy, which is consistent with an increase in the strength and frequency of southerly and easterly winds during winter. [ABSTRACT FROM AUTHOR]

The movements of two adult female polar bears (Ursus maritimus) in East Greenland and the Greenland Sea area were studied by use of satellite telemetry between the fall of 1994 and the summer of 1998. One female was tracked for 621 days, the other for 1,415 days. During this time the females used maternity dens on land. If denning periods on land were excluded, the two females used between 73% and 100% of the tracking time offshore where they were able to navigate in the dynamic pack ice and counteract the fast southward movement of the ice (up to 30 km/h) in the East Greenland Current. Mean monthly movement rates varied between 0.32 and 0.76km/h. Both bears had very large home ranges (242,000 and 468,000 km2) within the dynamic pack ice of the Greenland Sea. The facts that the bears made extensive use of the offshore sea ice and that there is a marked reduction of the Greenland Sea ice call for a closer monitoring of the effects of this change on the East Greenland polar bear population. [ABSTRACT FROM AUTHOR]

Retrievals of total sea ice concentration from four algorithms using the 85.5 GHz vertically and horizontally polarized channels of the Special Sensor Microwave Imager (SSM/I) over the marginal ice zone in the Barents and Greenland Seas are compared with retrievals of total sea ice concentration from helicopter-borne linescan camera observations made during a cruise of the R/V Polarstern during May–June 1997. The goals are to evaluate (1) SSM/I 85.5 GHz retrievals of total sea ice concentration for climatological purposes, and (2) the ability of 85.5 GHz data to show the sea ice edge through cloud cover, for operational purposes. The SSM/I 85.5 GHz channels offer a spatial resolution of 12.5 km, which is sufficient to resolve ice edge features and small polynyas; however, there is generally more atmospheric contamination of the sea ice signal at 85.5 GHz than at the lower frequencies (19 and 37 GHz) traditionally used for sea ice remote sensing. A self-adjusting algorithm that performs a nonlinear correction for atmospheric moisture, without explicit atmospheric input data, yields the best accuracy over total sea ice concentrations greater than 30%. However, this algorithm can misclassify clouds over open water as sea ice, and is therefore unreliable for locating the sea ice edge. The best algorithm for locating the sea ice edge is found to be the SEA LION algorithm, which explicitly uses meteorological reanalysis data to correct for atmospheric contamination. For total sea ice concentrations in the range 20–70%, empirical 85.5 GHz hybrids of lower-frequency algorithms developed at the NASA Goddard Space Flight Center can improve the accuracy of these algorithms. [Copyright &y& Elsevier]

Reports on a study on the rotifer fauna of arctic sea ice. Collection of the ice core samples from Barents Sea, Laptev Sea and Greenland Sea in the Arctic Ocean; Names of eight rotifer species; Discussion of the geographical, distribution and abundance of the species in the ice with regard to biotic and abiotic parameters of the sea ice environment.

Here we investigate the intensity of eddy generation and their properties in the marginal ice zone (MIZ) regions of Fram Strait and around Svalbard using spaceborne synthetic aperture radar (SAR) data from Envisat ASAR and Sentinel-1 in winter 2007 and 2018. Analysis of 2039 SAR images allowed identifying 4619 eddy signatures. The number of eddies detected per image per kilometer of MIZ length is similar for both years. Submesoscale and small mesoscale eddies dominate with cyclones detected twice more frequently than anticyclones. Eddy diameters range from 1 to 68 km with mean values of 6 km and 12 km over shallow and deep water, respectively. Mean eddy size grows with increasing ice concentration in the MIZ, yet most eddies are detected at the ice edge and where the ice concentration is below 20%. The fraction of sea ice trapped in cyclones (53%) is slightly higher than that in anticyclones (48%). The amount of sea ice trapped by a single 'mean' eddy is about 40 km2, while the average horizontal retreat of the ice edge due to eddy-induced ice melt is about 0.2–0.5 km·d–1 ± 0.02 km·d–1. Relation of eddy occurrence to background currents and winds is also discussed. [ABSTRACT FROM AUTHOR]

Presents a study on the interactions between ice cover and entrainment during winter when heat loss to the atmosphere is present. Use of a one-dimensional energy-balance model; Measurement of heat loss; Examination and comparison of the conditions appropriate for the Weddell Sea and the Greenland Sea with field observations; Numerical examples; Summary.

Presents a study on the abundance and biomass of the sea ice biota in the Greenland Sea. Estimation of the grazing impact of the sea ice meiofauna on the ice algal primary production; Materials and methods; Experimental results; Discussion.

Presents a study on the hydrographic structure beneath the Odden ice tongue in the Greenland Sea. Use of data from a transect across the Nordic Basin; Calculation of the sea-air heat fluxes and the rate of ice formation; Relevance of the Odden to the formation of the Greenland Sea Deep Water water mass.

Presents a study on the physical properties of sea ice in the Odden ice tongue of the Greenland Sea for the winter of 1992-1993. Ice sampling program in Odden 1993; Field observations from the F.S. Polarstern ship; Physical structure of pancake ice; Properties of frazil ice; Estimates of ice volume and salt flux; Summary.

Presents a study of the ice conditions in the Odden area of the Greenland Sea for the 1992-1993 winter season. Use of data from active and passive microwave sensors and airborne data; Relation of synthetic aperture radar imagery to Odden ice types; Description of ice in the 1992-1993 Odden.

Presents a study which employed and optimized an automatic drift algorithm to monitor the sea-ice drift velocity in the Greenland Sea. Estimation of the spatial distribution of the sea-ice mass flux; Derivation of ice velocity fields; Seasonal and spatial distributions of the sea-ice drift; Discussion.

Focuses on the European Subpolar Ocean Program (ESOP) of the European Commission which was developed to study the roles played by sea ice-ocean interactions in the Greenland Sea system. Origin and implementation of ESOP; Perspectives on ESOP scientific achievements; Investigation of the link between the uptake and vertical flux of carbon with other factors in the Greenland Sea.