Spatial and temporal structure of the Denmark Strait Overflow revealed by acoustic observations

Macrander, Annecke; Käse, Rolf H.; Send, Uwe; Valdimarsson, Héðinn; Jónsson, Steingrímur

doi:10.1007/s10236-007-0101-x

Cited by 57 publications

(72 citation statements)

References 29 publications

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“…To assess whether GLOB16 is capable of reproducing the strength of the overflow (here defined as σ θ > 27.8 kg m −3 ), the corresponding volume transport has been calculated both in the Denmark Strait and in the Faroe Bank Channel. The mean transport appears to be consistent with observations in the Denmark Strait, with a mean overflow transport of 2.7 Sv across the Denmark Strait, which slightly underestimates the longterm observed transport of ∼ 3 Sv (Macrander et al, 2007;Jochumsen et al, 2012). There is no clear seasonal cycle, and no discernible trend is detected for the whole period (Fig.…”

Section: Volume Transports Through Critical Sectionssupporting

confidence: 82%

A 1/16° eddying simulation of the global NEMO sea-ice–ocean system

et al. 2016

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Abstract. Analysis of a global eddy-resolving simulation using the NEMO general circulation model is presented. The model has 1/16 • horizontal spacing at the Equator, employs two displaced poles in the Northern Hemisphere, and uses 98 vertical levels. The simulation was spun up from rest and integrated for 11 model years, using ERA-Interim reanalysis as surface forcing. Primary intent of this hindcast is to test how the model represents upper ocean characteristics and sea ice properties.Analysis of the zonal averaged temperature and salinity, and the mixed layer depth indicate that the model average state is in good agreement with observed fields and that the model successfully represents the variability in the upper ocean and at intermediate depths. Comparisons against observational estimates of mass transports through key straits indicate that most aspects of the model circulation are realistic. As expected, the simulation exhibits turbulent behaviour and the spatial distribution of the sea surface height (SSH) variability from the model is close to the observed pattern. The distribution and volume of the sea ice are, to a large extent, comparable to observed values.Compared with a corresponding eddy-permitting configuration, the performance of the model is significantly improved: reduced temperature and salinity biases, in particular at intermediate depths, improved mass and heat transports, better representation of fluxes through narrow and shallow straits, and increased global-mean eddy kinetic energy (by ∼ 40 %). However, relatively minor weaknesses still exist such as a lower than observed magnitude of the SSH variability. We conclude that the model output is suitable for broader analysis to better understand upper ocean dynamics and ocean variability at global scales. This simulation represents a major step forward in the global ocean modelling at the Euro-Mediterranean Centre on Climate Change and constitutes the groundwork for future applications to short-range ocean forecasting.

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Section: Volume Transports Through Critical Sectionssupporting

confidence: 82%

A 1/16° eddying simulation of the global NEMO sea-ice–ocean system

et al. 2016

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“…The analysis of the DSOW and ISOW volume transport revealed, for both water masses, a mean transport of approximately 1.4 Sv. Observational estimations of the DSOW transport (Girton and Sanford, 2001;Macrander et al, 2007;Sarafanov et al, 2009) suggest a general stronger overflow in the range of 2.5 − 3.0 Sv. Further, the modelled mean salinity range of the DSOW (34.78 psu) and ISOW (34.89 psu) is too fresh compared to observed estimates, which suggest a DSOW and ISOW salinity in the range of 34.88 − 34.94 psu and 34.98 − 35.03 psu, respectively (Warren and Wunsch, 2007).…”

Section: Discussionmentioning

confidence: 98%

Evaluation of a Finite-Element Sea-Ice Ocean Model (FESOM) set-up to study the interannual to decadal variability in the deep-water formation rates

et al. 2013

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The characteristics of a global setup of the Finite-Element Sea-Ice Ocean Model (FESOM) under forcing of the period 1958-2004 are presented. The model setup is designed to study the variability in the deep-water mass formation areas and was therefore regionally better resolved in the deep-water formation areas in the Labrador Sea, Greenland Sea, Weddell Sea and Ross Sea. The sea-ice model reproduces realistic sea-ice distributions and variabilities in the sea ice extent of both hemispheres as well as sea ice transport that compares well with observational data. Based on a comparison between model and Ocean Weather Ship data in the North Atlantic, we observe that the vertical structure is well captured in areas with a high resolution. In our model setup we are able to simulate decadal ocean variability including several salinity anomaly events and corresponding fingerprint in the vertical hydrography. The ocean state of the model setup features pronounced variability in the Atlantic Meridional Overturning Circulation (AMOC) as well as the associated mixed layer depth pattern in the North Atlantic deep-water formation areas.

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“…The focus of this paper is on a comparative analysis of intra-seasonal variability along the Deep Western Boundary Current (DWBC) beginning shortly after exiting the subarctic regime at Denmark Strait (Macrander et al, 2007, Jochumsen et al, 2012. The investigation (Figure 1) follows the path of the DWBC along the East Greenland shelf break with the Angmagssalik array (Dickson et al, 2008), and toward the southern tip of Greenland and the Cape Farewell array (Bacon and Saunders, 2010).…”

Section: ) Introduction and Objectivesmentioning

confidence: 99%

“…The temporal resolution of the measurements is 20 minutes, but to reduce uncertainties the data were averaged to hourly values. Overflow transports were determined by Macrander et al (2007), and by Jochumsen et al (2012). The two ADCPs were deemed sufficient for estimating the overflow transport (Dickson et al, 2008).…”

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confidence: 99%

Intra-seasonal variability of the DWBC in the western subpolar North Atlantic

Fischer

Karstensen

Zantopp

et al. 2015

Progress in Oceanography

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The Deep Western Boundary Current (DWBC) along the western margin of the subpolar North Atlantic is an important component of the deep limb of the Meridional Overturning near its northern origins. A network of moored arrays from Denmark Strait to the tail of the Grand Banks has been installed for almost two decades to observe the boundary currents and transports of North Atlantic Deep Water as part of an internationally coordinated Observatory for the Atlantic Meridional Overturning Circulation. The dominant variability in all of the moored velocity time series is in the week-to-month period range. While the temporal characteristics of this variability changes only gradually between Denmark Strait and Flemish Cap, a broad band of longer term variability is present farther along the path of the DWBC at the Grand Banks and in the interior basins (Labrador and Irminger Seas). The vigorous intraseasonal variability may well mask possible interannual to decadal variability that is typically an order of magnitude smaller than the high-frequency fluctuations. Here, the intra-seasonal variability at key positions along the DWBC path using both, observations and high resolution model data is quantified. The results are used to evaluate the model circulation, and in turn the model is used to relate the discrete measurements to the overall pattern of the subpolar circulation. Topographic waves are found to be trapped by the steep topography all around the western basins, the Labrador and Irminger Seas. In the Labrador Sea, the high intra-seasonal variability of the boundary current regime is separated by a region of extremely low variability in narrow recirculation cells from the basin interior. There, the variability is also on intra-seasonal timescales, but at much longer periods around 50 days. We would like to thank reviewer #2 for his/her very careful evaluation of our manuscript, the constructive criticism and the recommendations for corrections and suggestions. Below, recommendations by the reviewer are in blue and our response in black.Review of "Intra-seasonal variability of the Deep Western Boundary Current in the western subpolar North Atlantic", Manuscript Number: PROOCE-D-13-00096 1 General comments: Using long current meter records in the western margin of the subpolar gyre, the authors investigate the intra-seasonal variability in the Deep Western Boundary Current. From the Denmark Strait to the Grand Banks they show -that the dominant variability is in the week-to-month period range -that 10 day periods dominate the variance, which they attribute to topographic Rossby waves -that at Flemish Cap and farther south, there is also variability at longer periods -that in the basin centers (Labrador and Irminger) the variance dominate at 50 day period and there is almost no variance at 10 days. Using a long time series in the DWBC at 53°N they also find seasonality in the intra-seasonal variability, with an offset of 6 months between the surface and the bottom. Then to validate a new high resolu...

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Spatial and temporal structure of the Denmark Strait Overflow revealed by acoustic observations

Cited by 57 publications

References 29 publications

A 1/16° eddying simulation of the global NEMO sea-ice–ocean system

A 1/16° eddying simulation of the global NEMO sea-ice–ocean system

Evaluation of a Finite-Element Sea-Ice Ocean Model (FESOM) set-up to study the interannual to decadal variability in the deep-water formation rates

Intra-seasonal variability of the DWBC in the western subpolar North Atlantic

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