A comparison of aircraft-based surface-layer observations over Denmark Strait and the Irminger Sea with meteorological analyses and QuikSCAT winds

2009 ◽  
Vol 135 (645) ◽  
pp. 2046-2066 ◽  
Author(s):  
I. A. Renfrew ◽  
G. N. Petersen ◽  
D. A. J. Sproson ◽  
G. W. K. Moore ◽  
H. Adiwidjaja ◽  
...  
Keyword(s):  
Surface Layer ◽  
Irminger Sea ◽  
Denmark Strait ◽  
Quikscat Winds

scholarly journals The East Greenland Spill Jet*

2005 ◽  
Vol 35 (6) ◽  
pp. 1037-1053 ◽  
Author(s):  
Robert S. Pickart ◽  
Daniel J. Torres ◽  
Paula S. Fratantoni
Keyword(s):  
Gulf Stream ◽  
Current System ◽  
Vertical Mixing ◽  
Relative Vorticity ◽  
Boundary Current ◽  
Velocity Measurements ◽  
East Greenland ◽  
Irminger Sea ◽  
Denmark Strait ◽  
Vorticity Analysis

Abstract High-resolution hydrographic and velocity measurements across the East Greenland shelf break south of Denmark Strait have revealed an intense, narrow current banked against the upper continental slope. This is believed to be the result of dense water cascading over the shelf edge and entraining ambient water. The current has been named the East Greenland Spill Jet. It resides beneath the East Greenland/Irminger Current and transports roughly 2 Sverdrups of water equatorward. Strong vertical mixing occurs during the spilling, although the entrainment farther downstream is minimal. A vorticity analysis reveals that the increase in cyclonic relative vorticity within the jet is partly balanced by tilting vorticity, resulting in a sharp front in potential vorticity reminiscent of the Gulf Stream. The other components of the Irminger Sea boundary current system are described, including a presentation of absolute transports.

scholarly journals Impact of Tectonic, Glacial and Contour Current Processes on the Late Cenozoic Sedimentary Development of the Southeast Greenland Margin

Geosciences ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 157 ◽  
Author(s):  
Katrien Heirman ◽  
Tove Nielsen ◽  
Antoon Kuijpers
Keyword(s):  
Ocean Circulation ◽  
Seismic Reflection Data ◽  
Accommodation Space ◽  
Reflection Data ◽  
Irminger Sea ◽  
Denmark Strait ◽  
Regional Tectonic ◽  
Glacial Periods ◽  
Greenland Margin ◽  
Entire Margin

To understand the geomorphological contrast between the northern and southern parts of the Southeast Greenland margin with its marked differences in sedimentary regime, bathymetric and seismic reflection, data have been compiled and analysed. While previous studies focused on selected parts of this margin, the present study provides an intergraded overview of the entire margin from Cap Farewell to Denmark Strait. The prominent north–south contrast shows a wide northern shelf and a narrow southern shelf. The origin of this width disparity can be traced back to the initial formation stage of the Irminger Sea due to regional differences in uplift versus oceanic subsidence. This regional tectonic discrepancy also created a difference in sediment accommodation space that, in combination with a weak ocean circulation regime, favoured formation of Oligocene–Miocene turbidite fan complexes along the lower southern slope. These fan complexes became the core of sediment drift ridges that strike perpendicular to the slope. Strong bottom currents, which gradually increase in strength towards the south, were mainly prevalent during warmer climate stages. During glacial periods, downslope transport of glacigenic sediments and hyperpycnal meltwater flow further shaped the large drift ridges and formed several relatively narrow, V-shaped turbidite channels extending towards the deep Irminger Sea basin. These V-shaped channels are still active today when cascading dense winter water from the shelf flows downwards along the shelf to the Irminger Sea basin.

Interpreting the observed variability of deep waters in the Irminger Sea

2021 ◽  
Author(s):  
Eva Prieto ◽  
Damien Desbruyères ◽  
Virginie Thierry
Keyword(s):  
World Ocean ◽  
Argo Floats ◽  
Irminger Sea ◽  
Deep Waters ◽  
Denmark Strait ◽  
Salinity Variability ◽  
World Ocean Atlas ◽  
Property Changes ◽  
Reference Section

<p><strong>Temperature and salinity seasonal to interannual variability of Iceland Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW) is investigated by combining two in-situ datasets in the Irminger Sea for the period 1997-2020: 12-yr of repeated hydrography (1997-2018) provided by the FOUREX, OVIDE and RREX sections and 4-yr of data (2016-2020) from 8 Deep Argo floats deployed in the region between 2016 and 2018. </strong></p><p><strong>In order to enable a consistent analysis of ocean temperature and salinity variability from unevenly distributed vertical profiles (both in space and time), it is necessary to estimate the appropriate regional climatology to be removed from every observation. Two independent procedures are followed to compute anomalies and quantify uncertainties related to the choice of climatology: First, the global 1°-resolution World Ocean Atlas 2018 (2005-2017 averages) climatology is retrieved from every observed profile (Deep Argo, hydrography). Second, </strong><span><strong>the well-known and sampled OVIDE transect (2002-2018 average) is used to build a reference section of geographical anomalies that are subsequently propagated along potential vorticity contours </strong></span><span><strong>in the Irminger Sea.</strong></span><strong> Neutral density surfaces 28.02 kgm</strong><sup><strong>-3 </strong></sup><strong>and 28.12 kgm</strong><sup><strong>-3</strong></sup><strong> are then chosen from mean OVIDE 2002-2018 gridded fields as representative of ISOW and DSOW levels, respectively. Significant decadal trends in water mass properties are revealed by repeated hydrography, whereas some striking boundary-interior spatial patterns are captured by Deep Argo floats. Property changes of ISOW and DSOW are discussed in terms of changes of source waters in the Nordic Seas, entrainment of Atlantic waters into the overflow waters and cascading events from the Greenland slope.</strong></p><p> </p>

Observed Denmark Strait Overflow Cyclones around Greenland

2021 ◽  
Author(s):  
Sijia Zou ◽  
Amy Bower ◽  
Heather Furey ◽  
Robert Pickart ◽  
Loïc Houpert ◽  
...  
Keyword(s):  
Continental Slope ◽  
Potential Vorticity ◽  
Small Radius ◽  
Rossby Number ◽  
Western Boundary ◽  
Boundary Current ◽  
Boundary Currents ◽  
Irminger Sea ◽  
Deep Western Boundary Current ◽  
Denmark Strait

<div> <p>Abundant cyclonic eddies are observed to travel along the Deep Western Boundary Current around Greenland by Lagrangian floats, hydrographic stations and moorings. Most of the cyclones have intensified rotations below the surface (700-1000 dbar), with maximum azimuthal velocities of ~30 cm/s at radii of ~10 km. The swift rotation and small radius lead to a relatively large Rossby number (~0.4), suggesting important contributions from the ageostrophic terms. The subsurface rotational core is also characterized with a local (both vertically and horizontally) potential vorticity (PV) maximum, which is associated with the pinching of isopycnals towards the mid-depths (i.e. high stratification). The PV structure suggests the origin of the cyclone as the Denmark Strait Overflow Cyclone. The latter is known to be formed by vortex stretching southwest of the Denmark Strait, where outflow waters with high PV from the sill descends the continental slope into the low PV Irminger Sea. Finally, we show that these cyclones can influence the boundary currents around Greenland by introducing property anomalies that originate from the Denmark Strait.</p> </div>

scholarly journals High-Frequency Variability in the Circulation and Hydrography of the Denmark Strait Overflow from a High-Resolution Numerical Model

2017 ◽  
Vol 47 (12) ◽  
pp. 2999-3013 ◽  
Author(s):  
Mattia Almansi ◽  
Thomas W. N. Haine ◽  
Robert S. Pickart ◽  
Marcello G. Magaldi ◽  
Renske Gelderloos ◽  
...  
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
Sea Surface ◽  
Cross Sectional ◽  
Irminger Sea ◽  
Denmark Strait ◽  
High Frequency Variability ◽  
Lateral Extent ◽  
Initial Results ◽  
Good Agreement

AbstractInitial results are presented from a yearlong, high-resolution (~2 km) numerical simulation covering the east Greenland shelf and the Iceland and Irminger Seas. The model hydrography and circulation in the vicinity of Denmark Strait show good agreement with available observational datasets. This study focuses on the variability of the Denmark Strait overflow (DSO) by detecting and characterizing boluses and pulses, which are the two dominant mesoscale features in the strait. The authors estimate that the yearly mean southward volume flux of the DSO is about 30% greater in the presence of boluses and pulses. On average, boluses (pulses) are 57.1 (27.5) h long, occur every 3.2 (5.5) days, and are more frequent during the summer (winter). Boluses (pulses) increase (decrease) the overflow cross-sectional area, and temperatures around the overflow interface are colder (warmer) by about 2.6°C (1.8°C). The lateral extent of the boluses is much greater than that of the pulses. In both cases the along-strait equatorward flow of dense water is enhanced but more so for pulses. The sea surface height (SSH) rises by 4–10 cm during boluses and by up to 5 cm during pulses. The SSH anomaly contours form a bowl (dome) during boluses (pulses), and the two features cross the strait with a slightly different orientation. The cross streamflow changes direction; boluses (pulses) are associated with veering (backing) of the horizontal current. The model indicates that boluses and pulses play a major role in controlling the variability of the DSO transport into the Irminger Sea.

scholarly journals Contrasting drivers and trends of ocean acidification in the subarctic Atlantic

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fiz F. Pérez ◽  
Jon Olafsson ◽  
Solveig R. Ólafsdóttir ◽  
Marcos Fontela ◽  
Taro Takahashi
Keyword(s):  
Surface Layer ◽  
Calcium Carbonate ◽  
Deep Layer ◽  
Strong Increase ◽  
The North ◽  
Irminger Sea ◽  
Main Driver ◽  
Decreasing Ph ◽  
Driver Analysis ◽  
Positive Effect

AbstractThe processes of warming, anthropogenic CO2 (Canth) accumulation, decreasing pHT (increasing [H+]T; concentration in total scale) and calcium carbonate saturation in the subarctic zone of the North Atlantic are unequivocal in the time-series measurements of the Iceland (IS-TS, 1985–2003) and Irminger Sea (IRM-TS, 1983–2013) stations. Both stations show high rates of Canth accumulation with different rates of warming, salinification and stratification linked to regional circulation and dynamics. At the IS-TS, advected and stratified waters of Arctic origin drive a strong increase in [H+]T, in the surface layer, which is nearly halved in the deep layer (44.7 ± 3.6 and 25.5 ± 1.0 pmol kg−1 yr−1, respectively). In contrast, the weak stratification at the IRM-TS allows warming, salinification and Canth uptake to reach the deep layer. The acidification trends are even stronger in the deep layer than in the surface layer (44.2 ± 1.0 pmol kg−1 yr−1 and 32.6 ± 3.4 pmol kg−1 yr−1 of [H+]T, respectively). The driver analysis detects that warming contributes up to 50% to the increase in [H+]T at the IRM-TS but has a small positive effect on calcium carbonate saturation. The Canth increase is the main driver of the observed acidification, but it is partially dampened by the northward advection of water with a relatively low natural CO2 content.

scholarly journals On the Cascading of Dense Shelf Waters in the Irminger Sea

2012 ◽  
Vol 42 (12) ◽  
pp. 2254-2267 ◽  
Author(s):  
Anastasia Falina ◽  
Artem Sarafanov ◽  
Herlé Mercier ◽  
Pascale Lherminier ◽  
Alexey Sokov ◽  
...  
Keyword(s):  
Continental Slope ◽  
Western Boundary ◽  
Boundary Current ◽  
East Greenland ◽  
Low Salinity ◽  
East Greenland Current ◽  
Irminger Sea ◽  
Deep Western Boundary Current ◽  
Deep Waters ◽  
Denmark Strait

Abstract Hydrographic data collected in the Irminger Sea in the 1990s–2000s indicate that dense shelf waters carried by the East Greenland Current south of the Denmark Strait intermittently descend (cascade) down the continental slope and merge with the deep waters originating from the Nordic Seas overflows. Repeat measurements on the East Greenland shelf at ~200 km south of the Denmark Strait (65°–66°N) reveal that East Greenland shelf waters in the Irminger Sea are occasionally as dense (σ0 > 27.80) as the overflow-derived deep waters carried by the Deep Western Boundary Current (DWBC). Clear hydrographic traces of upstream cascading of dense shelf waters are found over the continental slope at 64.3°N, where the densest plumes (σ0 > 27.80) originating from the shelf are identified as distinct low-salinity anomalies in the DWBC. Downstream observations suggest that dense fresh waters descending from the shelf in the northern Irminger Sea can be distinguished in the DWBC up to the latitude of Cape Farewell (~60°N) and that these waters make a significant contribution to the DWBC transport.

scholarly journals Bottom fishes from the Denmark Strait and Irminger sea : species list and individual data

1978 ◽  
Author(s):  
Gerhard Krefft ◽  
Richard L. Haedrich
Keyword(s):  
Individual Data ◽  
Species List ◽  
Irminger Sea ◽  
Denmark Strait

scholarly journals Cyclonic eddies in the West Greenland Boundary Current System

2021 ◽  
Author(s):  
Astrid Pacini ◽  
Robert S. Pickart ◽  
Isabela A. Le Bras ◽  
Fiammetta Straneo ◽  
N.P. Holliday ◽  
...  
Keyword(s):  
Propagation Velocity ◽  
Current System ◽  
Labrador Sea ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Irminger Sea ◽  
Denmark Strait ◽  
Integral Role ◽  
Thick Lens

AbstractThe boundary current system in the Labrador Sea plays an integral role in modulating convection in the interior basin. Four years of mooring data from the eastern Labrador Sea reveal persistent mesoscale variability in the West Greenland boundary current. Between 2014 and 2018, 197 mid-depth intensified cyclones were identified that passed the array near the 2000 m isobath. In this study, we quantify these features and show that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. A composite cyclone is constructed revealing an average radius of 9 km, maximum azimuthal speed of 24 cm/s, and a core propagation velocity of 27 cm/s. The core propagation velocity is significantly smaller than upstream near Denmark Strait, allowing them to trap more water. The cyclones transport a 200-m thick lens of dense water at the bottom of the water column, and increase the transport of DSOW in the West Greenland boundary current by 17% relative to the background flow. Only a portion of the features generated at Denmark Strait make it to the Labrador Sea, implying that the remainder are shed into the interior Irminger Sea, are retroflected at Cape Farewell, or dissipate. A synoptic shipboard survey east of Cape Farewell, conducted in summer 2020, captured two of these features which shed further light on their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea—a discovery that could have important implications for interior stratification.

Sign in / Sign up

Export Citation Format

Share Document