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We assess the contribution of flow over the Northeast Greenland Shelf (NEGS) to the total freshwater transport (FWT) through the Fram Strait. We analyze available observations since 2013 consisting of hydrographic sections, new mooring data, and surface‐geostrophic velocity and ERA5 winds. We provide first seasonal estimates of the FWT over the entire shelf and find a net southward FWT between 47 and 56 mSv (reference salinity 34.9), or ∼40%–45% of the total FWT through the Fram Strait. In summer, the long‐term mean FWT east of 8°W cumulates to 27 mSv southward, there is no trend toward increasing FWT, and new mooring data show a large seasonal cycle. We show that the NEGS contributes significantly to the Arctic freshwater outflow, however, uncertainty is high. To close the Arctic freshwater budget and provide better FWT estimates to the North Atlantic, sustained year‐round observations on the NEGS are essential. Plain Language Summary: We use new observations since 2013 to calculate transport over the Northeaster Greenland Shelf for the first time, and investigate how much it adds to the transport of the East Greenland Current over the shelf break which is monitored by moorings. Over most of the shelf, direct observations of ocean properties are limited to summer. Thus, we use remote‐sensing and wind reanalysis data, with shelf‐wide and year‐round coverage, but higher uncertainty, to estimate the year‐round transport of low‐salinity water (freshwater, less than 34.9) over the entire shelf. We find that on the shelf, freshwater transport is at least 40% of the total in Fram Strait. Still, uncertainty is high and year‐round, direct observations in the western part of the shelf are required to provide accurate estimates for the Arctic freshwater outflow. Key Points: Summer freshwater transport (FWT) over the shelf cumulates to −27 mSv and shows no trend in timeNew mooring data on the shelf at 10.1°W show a very large seasonal cycleYear‐round FWT over the shelf is estimated to ∼−52 mSv or 43% of the total freshwater outflow from the Fram Strait [ABSTRACT FROM AUTHOR]

Transports of total volume and water masses obtained from a mooring array in the East Greenland Current (EGC) in Fram Strait are presented for the period 1997–2009. The array in the EGC was moved along isobaths from 79°N to 78 ° 50 ′ N in 2002 to line up with moorings in the eastern Fram Strait. Analysis of the time series at the two latitudes shows that associated with the southward move, the annual mean volume transport of the EGC increased from 5.8±1.8 Sv to 8.7±2.5 Sv, mostly related with an increase in barotropic flow. This suggests a recirculation of close to 3 Sv at 78 ° 50 ′ N as a consequence of the large-scale wind-driven cyclonic gyre in the Nordic Seas. In addition, the volume transport at 78 ° 50 ′ N showed a clear seasonal cycle which was absent at 79°N. Estimates of the wind-driven Sverdrup transport at two different latitudes show that the difference in total volume transport and seasonality can largely be explained by the wind-stress curl. However, weak transport in 2003 was only partially related with weak Sverdrup transport and coincided also with anomalously weak northerly winds. The stronger recirculation at 78 ° 50 ′ N has also consequences for the observed Atlantic Water: there is significantly more Atlantic derived water present at the southerly latitude. In addition, the warm anomaly in Fram Strait between 2005 and 2007 doubled the amount of Recirculated Atlantic Water temporarily. Finally, we estimate that close to 2.7 Sv, or 50%, of Atlantic derived water recirculates in Fram Strait. [ABSTRACT FROM AUTHOR]

Abstract: The influence of a large meridional submarine ridge on the decay of Agulhas rings is investigated with a 1 and 2-layer setup of the isopycnic primitive-equation ocean model MICOM. In the single-layer case we show that the SSH decay of the ring is primarily governed by bottom friction and secondly by the radiation of Rossby waves. When a topographic ridge is present, the effect of the ridge on SSH decay and loss of tracer from the ring is negligible. However, the barotropic ring cannot pass the ridge due to energy and vorticity constraints. In the case of two-layer ring the initial SSH decay is governed by a mixed barotropic–baroclinic instability of the ring. Again, radiation of barotropic Rossby waves is present. When the ring passes the topographic ridge, it shows a small but significant stagnation of SSH decay, agreeing with satellite altimetry observations. This is found to be due to a reduction of the growth rate of the instability, to conversions of kinetic energy to the upper layer, and to a decrease in Rossby-wave radiation. The energy transfer is related to the fact that coherent structures in the lower layer cannot pass the steep ridge due to energy constraints. Furthermore, the loss of tracer from the ring through filamentation is less than for a ring moving over a flat bottom, related to a decrease in propagation speed of the ring. We conclude that ridges like the Walvis Ridge tend to stabilize a multi-layer ring and reduce its decay. [Copyright &y& Elsevier]

Abstract: Regional hydrographic and current observations from the 2005 MaudNESS winter field campaign in the Maud Rise seamount region of the eastern Weddell Sea show that an annular Halo consisting largely of Warm Deep Water (WDW) encircled the Rise at depths just below the mixed layer. The Halo was associated with elevated isopycnals and, on the northern flank of the Rise, strong subsurface velocities up to 20cms−1. Intercomparison of these observations with winter 1986 and 1994 conditions confirms the presence of the Halo and suggests that it, and associated warm pools west of the Rise, are at least semipermanent features of the region. These observational results compare well with the output from an isopycnic ocean model for a variety of parameters including shape of the seamount, inflow conditions and vertical stratification. The model captures processes associated with a steady westward flow impinging on the isolated seamount and shows (1) that the dynamics of the warm-water Halo with a shallow mixed layer are related to the formation of a jet surrounding the Rise and the overlying Taylor column and (2) that eddies of alternating sign (cyclones and anticyclones) are formed from instability of the jet-like flow structure, and are subsequently shed from the western flanks of the Rise. The eddies closest to the rise are dominated by cyclones which tend to adhere to the flanks more strongly than anticyclones. The formation and passage of approximately 3–5 eddies per year is seen in the sea-surface-height anomalies over a 12-year period. Despite apparent spatial and temporal variability in the dynamics of the Halo and shedding of eddies, the time-mean picture is such that significantly elevated isopycnals with WDW below the mixed layer are always present on the flanks of Maud Rise. This mechanism likely contributes annually to earlier seasonal ice loss in the eastern Weddell Sea than farther west. For unusually strong inflow conditions, possibly due to large-scale interannual variability, the Halo becomes more intense and overlies a much larger part of Maud Rise, potentially preconditioning the area for deep ocean ventilation and a subsequent polynya event such as observed in the 1970s. [Copyright &y& Elsevier]

In a numerical, isopycnal, ocean model the mixing is investigated with the environment of two idealized Agulhas rings, one that splits, and one that remains coherent. The evolution of a passive tracer, initially contained within the rings, shows that tracer leakage is associated with the formation of filaments in the early stage of ring evolution. These filaments reach down to the thermocline. In the deepest layers leakage occurs on a larger scale. Self-advection of the rings is very irregular, and it is not possible to compute a Lagrangian boundary in order to estimate the transport of leakage from the rings. To describe the processes that govern tracer leakage, in a coordinate frame moving with the ring a kinematic separatrix is defined in the streamfunction field for the nondivergent flow. Initially, filaments arise because of the elongation of the ring, which is mainly governed by an m = 2 instability that is collaborating with differential rotation. Because of beta, the symmetry is destroyed related to the separatrix associated with a stagnation point in the flow. The filament upstream of the stagnation point grows much faster and is associated with the bulk of tracer leakage. Mixing is enhanced by time dependence of the separatrix. As a result, there are no large differences between the leakage from a coherent ring, where the m = 2 instability equilibrates, and from a splitting ring, where the m = 2 instability keeps growing, which confirms that the amount of leakage is mainly governed by the ring's initial deformation combined with unsteady self-advection of the ring and not by the splitting of the ring. The decay of tracer content in the thermocline shows that in the first months up to 40% of the ring water can be mixed with the environment. In deeper layers the decay of tracer content may reach up to 90%. [ABSTRACT FROM AUTHOR]

The early Sea-Surface Height (SSH) decay of an Agulhas ring is studied using a circular symmetric, equivalent barotropic idealization of ring Astrid, which was measured during the first MARE-cruise. Observations indicate that the SSH of Agulhas rings most rapidly decays just after shedding. It is found that the observed initial fast decay of ring Astrid can be recovered by a numerical model and that a mixed baroclinic/barotropic instability accounts for most of the observed decay of SSH.In addition, a series of numerical experiments is presented in which the effects on the decay of ring strength, barotropic component, diameter, radial profile, β, and cooling were investigated. In all cases discussed, rings are linearly unstable to an m=2 mode. The evolution of the first 10 days is well predicted by a linear stability analysis. Further growth of the m=2 mode leads in most cases to split-up of the ring. The SSH decay of the rings is associated with a conversion from available potential energy of the parent ring to kinetic energy of nearly barotropic higher modes. Most of the energy release is associated with the m=2 mode. Also, the parent ring features an energy conversion from its barotropic to its baroclinic components.A strong barotropic component associated with a corotating ring is essential for SSH decay to occur. Counterrotating rings may feature SSH increase by energy conversion from the baroclinic to the barotropic component. For corotating rings SSH decay becomes weaker when the instability develops less vigorous. The simulation of ring Astrid shows that tracer loss from the core scales well with the decay of SSH. In the thermocline the associated mixing of fluid occurs preferably at the extremes of the elongating ring. At the deepest levels mixing is associated with dispersion through Rossby-wave radiation. [Copyright &y& Elsevier]

To provide an observational basis for the Intergovernmental Panel on Climate Change projections of a slowing Atlantic meridional overturning circulation (MOC) in the 21st century, the Overturning in the Subpolar North Atlantic Program (OSNAP) observing system was launched in the summer of 2014. The first 21-month record reveals a highly variable overturning circulation responsible for the majority of the heat and freshwater transport across the OSNAP line. In a departure from the prevailing view that changes in deep water formation in the Labrador Sea dominate MOC variability, these results suggest that the conversion of warm, salty, shallow Atlantic waters into colder, fresher, deep waters that move southward in the Irminger and Iceland basins is largely responsible for overturning and its variability in the subpolar basin. [ABSTRACT FROM AUTHOR]

Effective science communication is essential to share knowledge and recruit the next generation of researchers. Science communication to the general public can, however, be hampered by limited resources and a lack of incentives in the academic environment. Various social media platforms have recently emerged, providing free and simple science communication tools to reach the public and young people especially, an audience often missed by more conventional outreach initiatives. While individual researchers and large institutions are present on social media, smaller research groups are underrepresented. As a small group of oceanographers, sea ice scientists, and atmospheric scientists at the Norwegian Polar Institute, we share our experience establishing, developing, and maintaining a successful Arctic science communication initiative (@oceanseaicenpi) on Instagram, Twitter, and Facebook. The initiative is run entirely by a team of researchers with limited time and financial resources. It has built a broad audience of more than 7,000 followers, half of which is associated with the team’s Instagram account. To our knowledge, @oceanseaicenpi is one of the most successful Earth sciences Instagram accounts managed by researchers. The initiative has boosted the alternative metric scores of our publications and helped participating researchers become better writers and communicators. We hope to inspire and help other research groups by providing some guidelines on how to develop and conduct effective science communication via social media. [ABSTRACT FROM AUTHOR]

Abstract: During the 4th International Polar Year 2007–2009 (IPY), it has become increasingly obvious that we need to prepare for a new era in the Arctic. IPY occurred during the time of the largest retreat of Arctic sea ice since satellite observations started in 1979. This minimum in September sea ice coverage was accompanied by other signs of a changing Arctic, including the unexpectedly rapid transpolar drift of the Tara schooner, a general thinning of Arctic sea ice and a double-dip minimum of the Arctic Oscillation at the end of 2009. Thanks to the lucky timing of the IPY, those recent phenomena are well documented as they have been scrutinized by the international research community, taking advantage of the dedicated observing systems that were deployed during IPY. However, understanding changes in the Arctic System likely requires monitoring over decades, not years. Many IPY projects have contributed to the pilot phase of a future, sustained, observing system for the Arctic. We now know that many of the technical challenges can be overcome. The Norwegian projects iAOOS-Norway, POLEWARD and MEOP were significant ocean monitoring/research contributions during the IPY. A large variety of techniques were used in these programs, ranging from oceanographic cruises to animal-borne platforms, autonomous gliders, helicopter surveys, surface drifters and current meter arrays. Our research approach was interdisciplinary from the outset, merging ocean dynamics, hydrography, biology, sea ice studies, as well as forecasting. The datasets are tremendously rich, and they will surely yield numerous findings in the years to come. Here, we present a status report at the end of the official period for IPY. Highlights of the research include: a quantification of the Meridional Overturning Circulation in the Nordic Seas (“the loop”) in thermal space, based on a set of up to 15-year-long series of current measurements; a detailed map of the surface circulation as well as characterization of eddy dispersion based on drifter data; transport monitoring of Atlantic Water using gliders; a view of the water mass exchanges in the Norwegian Atlantic Current from both Eulerian and Lagrangian data; an integrated physical–biological view of the ice-influenced ecosystem in the East Greenland Current, showing for instance nutrient-limited primary production as a consequence of decreasing ice cover for larger regions of the Arctic Ocean. Our sea ice studies show that the albedo of snow on ice is lower when snow cover is thinner and suggest that reductions in sea ice thickness, without changes in sea ice extent, will have a significant impact on the arctic atmosphere. We present up-to-date freshwater transport numbers for the East Greenland Current in the Fram Strait, as well as the first map of the annual cycle of freshwater layer thickness in the East Greenland Current along the east coast of Greenland, from data obtained by CTDs mounted on seals that traveled back and forth across the Nordic Seas. We have taken advantage of the real-time transmission of some of these platforms and demonstrate the use of ice-tethered profilers in validating satellite products of sea ice motion, as well as the use of Seagliders in validating ocean forecasts, and we present a sea ice drift product – significantly improved both in space and time – for use in operational ice-forecasting applications. We consider real-time acquisition of data from the ocean interior to be a vital component of a sustained Arctic Ocean Observing System, and we conclude by presenting an outline for an observing system for the European sector of the Arctic Ocean. [Copyright &y& Elsevier]

In this paper we analyze how oceanic circulation affects sediment deposition along a sector of the Ross Sea continental margin, between the Iselin Bank and the Hillary Canyon, and how these processes evolved since the Late Miocene. The Hillary Canyon is one of the few places around the Antarctic continental margin where the dense waters produced onto the continental shelf, mainly through brine rejection related to sea ice production, flow down the continental slope and reach the deep oceanic bottom layer. At the same time the Hillary Canyon represents a pathway for relatively warm waters, normally flowing along the continental slope within the Antarctic Slope Current, to reach the continental shelf. The intrusion of warm waters onto the continental shelf produces basal melting of the ice shelves, reduces their buttressing effect and triggers instabilities of the ice sheet that represent one of the main uncertainties in future sea level projections. For this study we use seismic, morpho-bathymetric and oceanographic data acquired in 2017 by the R/V OGS Explora. Seismic profiles and multibeam bathymetry are interpreted together with age models from two drilling sites (U1523 and U1524) of the International Ocean Discovery Program (IODP) Expedition 374. Oceanographic data, together with a regional oceanographic model, are used to support our reconstruction by showing the present-day oceanographic influence on sediment deposition. Regional correlation of the main seismic unconformities allows us to identify eight seismic sequences. Seismic profiles and multibeam bathymetry show a strong influence of bottom current activity on sediment deposition since the Early Miocene and a reduction in their intensity during the mid-Pliocene Warm Period. Oceanographic data and modelling provide evidence that the bottom currents are related to the dense waters produced on the Ross Sea continental shelf and flowing out through the Hillary Canyon. The presence of extensive mass transport deposits and detachment scarps indicate that also mass wasting participates in sediment transport. Through this integrated approach we regard the area between the Iselin Bank and the Hillary Canyon as a Contourite Depositional System (ODYSSEA CDS) that offers a record of oceanographic and sedimentary conditions in a unique setting. The hypotheses presented in this work are intended to serve as a framework for future reconstructions based on detailed integration of lithological, paleontological, geochemical and petrophysical data. [Display omitted] •Contourite drifts between the Iselin Bank and the Hillary Canyon. •During warmer intervals the bottom currents are less intense. •Drifts produced by downslope flow of Ross Sea Bottom Water and Along Slope Current. •Evolution of the Contourite Depositional System since the Early Miocene. •Context for Integrated Ocean Discovery Program Expedition 374. [ABSTRACT FROM AUTHOR]