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Measurements of oceanographic characteristics, currents, and tides in the Fram Strait and the Greenland Sea are analyzed using historical measurement data. Measurements on moorings across the Fram Strait made it possible to estimate the speeds of the East Greenland and West Spitsbergen currents. It is shown that the speeds of these currents are low (within 10 cm/s) and the amplitudes of the speed of tidal currents are two or more times greater. Tidal currents are intensifying on the shelf of Greenland and Svalbard. Direct measurements are compared with the University of Oregon barotropic tide model. [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]

Abstract: Atlantic Water (AW) transported from the Nordic Seas is the major source of oceanic heat to the Arctic Ocean. Based on results from the TOPAZ reanalysis, a regional coupled ice‐ocean data assimilation system, we show that interannual variability of AW temperature in the Fram Strait (FS) is associated with the strength of the Greenland Sea gyre (GSG) circulation. The response of the GSG to the anomalous wind stress curl over the Nordic Seas modifies the AW inflow and thus influences the variability of AW temperature in the FS. A stronger (weaker) GSG circulation increases (decreases) the AW flow speed toward FS, leading to increased (decreased) oceanic heat content and higher (lower) AW temperature therein. This implies that the Nordic Seas circulation is not only a passive conduit of AW, but its response to overlying atmospheric variability can also largely influence the AW temperature in the FS by modifying the transport of AW. [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]

Our long-term study on top predator (seabirds and marine mammals) distribution in polar marine ecosystems aims at detecting possible temporal and spatial population changes, especially in the context of global changes in temperature and ice cover. Quantitative data on the seabird distribution were collected in the northern Greenland Sea and Fram Strait onboard the icebreaker RV Polarstern between 1988 and 2014, applying 30-min transect counts from the bridge, without width limitation ( n = 7320). A drastic decrease in numbers by a factor of seven was detected for the ivory gull Pagophila eburnea from 2007 on. These data confirm the decrease of ivory gull previously detected in North Canada and North Greenland, leading to the conclusion that the species is 'endangered' or 'near threatened'. These changes are discussed in relation to the decreasing Arctic pack ice coverage leading to the opening of the Northwest and Northeast Passages in 2007, at the time the year with the lowest ice coverage ever recorded. On the other hand, the decrease was even stronger for Ross's gull Rhodostethia rosea after 1993, apparently reflecting changes in migratory habits. The third high Arctic gull, Sabine's gull Xema sabini, was only tallied in very low numbers, without any clear temporal evolution in numbers. [ABSTRACT FROM AUTHOR]

The grain size of sortable silt (SS, 10-63mm) was studied in sediment core JM04-025PC from a sediment drift on the lower part of the western Svalbard slope. The study aims to reconstruct the bottom current activity and intermediate water circulation in the Greenland Sea. The SS record covers the last 74 ka and shows consistent millennial-scale oscillations in grain size. The youngest part of the record (<25 ka) is well correlated with the few available previously published reconstructions of grain size from the North Atlantic Ocean and the Nordic seas. Fining of SS occurs during four well-known regional cold climatic intervals, the 8.2-ka cold spell, the Younger Dryas and North Atlantic Heinrich Events H1 and H2, as well as during a local meltwater event at 14.4- 14.7 ka, possibly coinciding with the Older Dryas. Also before 25 ka, grain size oscillated in pace with the Northern Hemisphere climate with finer grain sizes during cold periods and coarser grain sizes during warm periods. The fining of SS indicates reduced bottom current strength and reduced water exchange between the Greenland Sea and the Arctic Ocean during regional climate cooling events, and probably also reduced deep ocean convection in the Greenland Sea gyre. [ABSTRACT FROM AUTHOR]

Rudels, B., Korhonen, M., Budéus, G., Beszczynska-Möller, A., Schauer, U., Nummelin, A., Quadfasel, D., and Valdimarsson, H. 2012. The East Greenland Current and its impacts on the Nordic Seas: observed trends in the past decade. – ICES Journal of Marine Science, 69: 841–851.For the past 30 years, it has been known that dense waters are created in the Arctic Ocean. However, before the late 1980s, observations indicated that Arctic Ocean deep waters only modified the deep water in the Greenland Sea, which was still thought of as the major source of dense water. In the mid-1990s, this picture began to fade. The deep convection in the Greenland Sea weakened and only Arctic Intermediate Water was formed. A deep salinity maximum was reinforced and a temperature maximum emerged at mid-depth. The densities of the salinity and temperature maxima were those of the deep waters in the Arctic Ocean, and one possibility was that waters below the convection were ventilated by Arctic Ocean deep waters from the East Greenland Current. Between 1998 and 2010, the salinity and temperature of the deep water in the Greenland Sea increased, implying continuous input from the East Greenland Current. Water from the Greenland Sea advected to Fram Strait now has almost Arctic Ocean characteristics and cannot significantly change the outflowing Arctic Ocean waters by mixing in the East Greenland Current, leading to a more-rapid transformation of the deep Greenland Sea water column. [ABSTRACT FROM PUBLISHER]

mong the most numerous seabird and pinniped species of the Fram Strait and the Greenland Sea, little auks Alle alle and harp seals Pagophila (Phoca) groenlandica are very abundant in the mixed Polar/Arctic Waters at the front between the two water masses. This must reflect the presence of very high concentrations of their food, Arctic zooplankton and nekton, massively attracting their predators. Such a high biological production seems to be depending on new primary production based on upwelling and high nutrient concentration. This usually takes place at the ice edge (e.g. July 2005), but hydrological conditions such as eddies can modify its position, east of the front in open water as caused by a subsurface eddy (August 2005), or in ice-covered areas if westerly winds push the pack ice to the east, eventually covering an eddy and causing very high concentrations of little auks and harp seals (July 2008). On the other hand, a dramatic decrease of pack ice coverage can move this water mass farther north and west, making it inaccessible to little auks during their breeding season, and apparently causing breeding failure in Jan Mayen in July 2005. In future years, if a much stronger diminution in sea ice coverage will take place, similar to the retreat in 2005 and 2007, the failure might affect the whole Spitsbergen population, as well as other seabird species feeding mainly at the ice edge. [ABSTRACT FROM AUTHOR]

We discuss the model representation of volume transports through one of the most climate-relevant ocean passages, the Fram Strait. We compare results from a coupled ocean–sea ice model with different resolutions (∼1/12° and ∼1/4°) and measurements from a mooring array along 79° N. The 1/4° model delivers a realistic mean climate state and realistic net volume transports. However, this model fails to reproduce the observed intense barotropic recirculation that reaches far north in Fram Strait. This recirculation is captured in the higher resolution version of the model. Other differences exist in the circulation over the East Greenland Shelf and in the temperature of Atlantic waters in the Fram Strait region as well as in surface heat fluxes. We find that a combination of high-resolution model results and long-term measurements can improve the interpretation of measured and simulated processes and reduce the uncertainties in exchange rates between Arctic and the North Atlantic. [ABSTRACT FROM AUTHOR]

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]