Internal drainage network and characteristics of the Aldegondabreen runoff (West Spitsbergen)

The polythermal Aldegondabreen is one of the most widely studied glaciers of the Nordenskjöld Land (Svalbard). However, the structure of its internal drainage network remains poorly understood. In order to determine the position and hydro-chemical characteristics of the surface and internal drainage channels of the glacier complex studies were carried out including ground penetrating radar (GPR) measurements and hydrological surveys. The GPR profiling performed in 2018–2020 identified four channels of internal drainage network, two of which are found along the northern side of the glacier in the area of cold ice and are subglacial. The other two are located in the area of temperate ice along the southern side of the glacier and are englacial, stretching at the cold-temperate surface. At the outlet grotto, the subglacial waters have a bicarbonate-calcium composition and low salinity (electrical conductivity 30–40 μS/cm), inherited from the surface meltwater streams that enter the moulins in the upper part of the glacier. No noticeable increase in mineralization occurs during the movement of the flow along the glacier bed. The englacial channels’ waters at the outlet grotto have the same bicarbonate-calcium composition but a higher salinity (electrical conductivity 100 μS/cm), which we attribute to the filtration through the rocks of the riegel near the Aldegonda terminus, or, alternatively, to the influx of the groundwater at the same spot. Measuring the hydrochemistry of the Aldegonda river tributaries both on the glacier’s surface, at the grottos and on the moraine in the valley made it possible to identify the zone of enrichment of the main volume of the low-mineralization glacial meltwater of bicarbonate-calcium composition by the high-mineralization (electrical conductivity up to 760 μS/cm) groundwater of sulphate-calcium composition coming from the springs on the riegel in front of the glacier’s terminus in the central part of the Aldegonda Valley. Presumably, the springs are fed by the deep filtration of melted glacial waters along the Aldegonda subglacial talik.

Lagrangian measurements in the West Spitsbergen Current by Argo floats

<p>Almost 4000 operational Argo floats covering the world's ocean provide near-real-time data on its state. The Arctic is less covered than other waters, but observations collected by Argo floats are gaining in importance. By delivering year-round measurements from the water column down to 2000 m (or to the bottom) along float trajectories, they complement and enhance the synoptic data collected during ship campaigns or by fixed moorings. However, oceanographic measurements with autonomous platforms are significantly limited in the Arctic regions by the presence of sea ice.</p><p>Here we present results obtained by Argo floats deployed in 2012-2020 by the Institute of Oceanology Polish Academy of Sciences (IOPAN) during summer campaigns of RV Oceania. In most years, the Argo floats were launched in the eastern branch (core) and in the western branch of the West Spitsbergen Current (WSC) within the Atlantic water inflow towards the Arctic Ocean. Floats deployed in the WSC core drift predominantly northward over the shelf break and upper slope west of Svalbard. After passing Fram Strait the floats usually turn eastward and continue over the northern Svalbard shelf brake, being advected with the Svalbard Branch of the Atlantic inflow into the Arctic Ocean Boundary Current. The easternmost position reached by the IOPAN Argo float was 39.6°E. Ultimately all deployed floats submerge under the sea ice north of Svalbard or farther to the east and die under the ice. Argo floats deployed in the western WSC branch over the underwater ridges, usually recirculate to the west and continue southward with the East Greenland Current. The float WMO 3901851 that drifted to the Labrador Sea, reached the southernmost latitude of 52.5°N and have been working until now for 4.5 years, which is unusual in the Arctic conditions.    </p><p>The measurements collected in the Marginal Ice Zone are particularly interesting for studying the ocean-atmosphere-ice interactions at the boundary between open and ice-covered ocean as well as they can be used for developing the ice avoidance algorithms for the Argo floats and other under ice sensors and platforms. A number of profiles obtained by Argo floats under the sea ice provide unique measurements in the upper ocean layer that is usually inaccessible from other platforms (e.g., moorings). In 2020 several profiles were collected under the ice cover by Argo floats north of Svalbard and transmitted after the float emerged in the polynya. The eastward flow of warm (up to 4° C at 80 m depth) Atlantic water was observed along the float trajectory over the shelf break. Measurements by Argo floats, revealing the dynamics and transformation of the Atlantic water entering the Arctic Ocean, are compared with ship-borne observations collected during the IOPAN long-term observational program AREX and year-round data from IOPAN moorings deployed north of Svalbard under the A-TWAIN and INTAROS projects.</p>

Large-scale connections between Fram Strait recirculation and warm water pathways towards Greenland fjords

<p>In the last two decades, rising ocean temperatures have significantly contributed to the increased melting and retreat of marine-terminating glaciers along the coast of Greenland. Warming subsurface waters have also been shown to interact with the glaciers in Northeast Greenland, which until recently were considered stable, and caused their rapid retreat. The main source of these waters is the westward recirculation of subducted Atlantic Water (AW) in Fram Strait, which has shown a warming of up to 1° C over the past few decades.</p><p>In this study, the connection between the subsurface warm Atlantic Intermediate Water (AIW) found on the wide continental shelf of Northeast Greenland and in the fjords, and AW within the West Spitsbergen Current (WSC) is investigated using historical hydrographic observations and high-resolution numerical simulations with the Finite-Element Sea-ice Ocean Model (FESOM). We find that AW from the WSC takes between 10 – 14 months to recirculate across Fram Strait and reach the shelf break where it moves southwards. The pronounced inter-annual variability in the WSC is preserved as the water recirculates. However, the variability of temperature and AIW layer thickness on the shelf at seasonal or inter-annual time scales is at best weakly controlled by the AW temperature in the WSC. There is no significant correlation between AIW and the WSC anywhere on the shelf, suggesting advection from the WSC alone does not control AIW signals. The role of wind-driven, episodic upwelling is then investigated as a driver of transport of AIW from Fram Strait onto the shelf (following an approach by Münchow et al., 2020) where it then may follow the deep trough system towards the glaciers.</p>

Changes in Atlantic Water circulation patterns and volume transports North of Svalbard over the last 12 years (2008-2020)

<p>Atlantic Water (AW) enters the Arctic through Fram Strait as the West Spitsbergen Current (WSC). When reaching the south of Yermak Plateau, the WSC splits into the Svalbard, Yermak Pass and Yermak Branches. Downstream of Yermak Plateau, AW pathways remain unclear and uncertainties persist on how AW branches eventually merge and contribute to the boundary current along the continental slope. We took advantage of the good performance of the 1/12° Mercator Ocean model in the Western Nansen Basin (WNB) to examine the AW circulation and volume transports in the area. The model showed that the circulation changed in 2008-2020. The Yermak Branch strengthened over the northern Yermak Plateau, feeding the Return Yermak Branch along the eastern flank of the Plateau. West of Yermak Plateau, the Transpolar Drift likely shifted westward while AW recirculations progressed further north. Downstream of the Yermak Plateau, an offshore current developed above the 3800 m isobath, fed by waters from the Yermak Plateau tip. East of 18°E, enhanced mesoscale activity from the boundary current injected additional AW basin-ward, further contributing to the offshore circulation. A recurrent anticyclonic circulation in Sofia Deep developed, which also occasionally fed the western part of the offshore flow. The intensification of the circulation coincided with an overall warming in the upper WNB (0-1000 m), consistent with the progression of AW. This regional description of the changing circulation provides a background for the interpretation of upcoming observations.</p>

Seasonal and Mesoscale Variability of the Two Atlantic Water Recirculation Pathways in Fram Strait

<p>Atlantic Water, which is transported northward by the West Spitsbergen Current, partly recirculates (i.e. turns westward) in Fram Strait. This determines how much heat and salt reaches the Arctic Ocean, and how much joins the East Greenland Current on its southward path. We describe the Atlantic Water recirculation's location, seasonality, and mesoscale variability by analyzing the first observations from moored instruments at five latitudes in central Fram Strait, spanning a period from August 2016 to July 2018. We observe recirculation on the prime meridian at 78°50'N and 80°10'N, respectively south and north of the Molly Hole, and no recirculation further south at 78°10'N and further north at 80°50'N. At a fifth mooring location at 79°30'N, we observe some influence of the two recirculation branches. The southern recirculation is observed as a continuous westward flow that carries Atlantic Water throughout the year, though it may be subject to broadening and narrowing. It is affected by eddies in spring, likely due to the seasonality of mesoscale instability in the West Spitsbergen Current. The northern recirculation is observed solely as passing eddies on the prime meridian, which are strongest during late autumn and winter, and absent during summer. This seasonality is likely affected both by the conditions set by the West Spitsbergen Current and by the sea ice. Open ocean eddies originating from the West Spitsbergen Current interact with the sea ice edge when they subduct below the fresher, colder water. Additionally the stratification set up by sea ice presence may inhibit recirculation.</p>

Mass Balance of Austre Grønfjordbreen, Svalbard, 2006–2020, Estimated by Glaciological, Geodetic and Modeling Aproaches

Glacier mass balance measurements, reconstructions and modeling are the precondition for assessing glacier sensitivity to regional climatic fluctuations. This paper presents new glaciological and geodetic mass balance data of Austre Grønfjordbreen located in the western part of Nordenskiöld Land in Central Spitsbergen. The average annual mass balance from 2014 to 2019 was −1.59 m w.e. The geodetic mass balance from 2008 to 2017 was −1.34 m w.e. The mass balance was also reconstructed by the temperature-index model from 2006 to 2020 and by spatially-distributed energy-balance models for 2011–2015 and 2019. We found a cumulative mass balance of −21.62 m w.e. over 2006–2020. The calculated mass-balance sensitivity to temperature was −1.04 m w.e. °C−1, which corresponds to the highest glacier mass balance sensitivity among Svalbard glaciers. Sensitivity to precipitation change was 0.10 m w.e. for a 10% increase in precipitation throughout the balance year. Comparing the results of the current study with other glacier mass balance assessments in Svalbard, we found that Austre Grønfjordbreen loses mass most rapidly due to its location, which is mostly influenced by the warm West Spitsbergen Current, small area and low elevation range.

Age of monazite from metapelitic schists of Atomfjella and Mossel series, Western Ny Friesland, Spitsbergen according to the CHIME method

The article presents the results of CHIME (chemical Th–U-total Pb isochron method) dating of monazite from metamorphic rocks of Precambrian complexes located in the north part of the West Spitsbergen Island. It is shown that for rocks of Atomfjella Series and Mossel Series, monazite ages are coeval within error (Atomfjella Series: 381 ± 18 Ma, Mossel Series: 377 ± 23 Ma). These age estimates show that metamorphism of the crystalline basement possibly took place during the Late Caledonian orogeny.