Observed sources and variability of Nordic seas overflow

Eldevik, Tor; Nilsen, Jan Even Øie; Iovino, Doroteaciro; Olsson, Kristina; Sandø, Anne Britt; Drange, Helge

doi:10.1038/ngeo518

Cited by 172 publications

(177 citation statements)

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“…This implies an inflow of ∼0.1 Gt DIC ant y −1 , this is ∼5% of the annual global ocean accumulation. The NAW circulates and overturn in the Nordic seas and Arctic Ocean, and constitutes the primary source of the overflow waters crossing the Greenland-Scotland ridge [Eldevik et al, 2009]. As estimated in section 3.2, these waters transport ∼0.06 Gt DIC ant y −1 (3% of annual global ocean accumulation) into the deep North Atlantic.…”

Section: Discussionmentioning

confidence: 99%

“…The total flux of cold overflow water across the ridge has been estimated to almost 6 Sv [Hansen and Østerhus, 2000]. The mean properties of the water were summarized by Eldevik et al [2009]. The Denmark Strait overflow water spans the theta and salinity ranges of approximately 0-0.5°C and 34.85-34.9, respectively, while the respective ranges for Faeroe-Shetland Channel overflow water are approximately 0-0.5°C, and 34.9-34.94.…”

Section: Anthropogenic Co 2 Distributionmentioning

confidence: 99%

“…The Nordic seas (Figure 1) are potentially important in this respect, as they annually generate 6 Sv of overflow water [Hansen and Østerhus, 2000], which is a main source of North Atlantic deep water [Dickson and Brown, 1994]. The overflow water is primarily formed by modification of North Atlantic Water (NAW) that enters from further south as the northward extension of the Gulf Stream, North Atlantic Current and North Atlantic Drift system [Eldevik et al, 2009] and which have high concentrations of DIC ant [Olsen et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

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Nordic seas transit time distributions and anthropogenic CO₂

et al. 2010

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[1] The distribution and inventory of anthropogenic carbon (DIC ant ) in the Nordic seas are determined using the transit time distribution (TTD) approach. To constrain the shape of the TTDs in the Nordic seas, CO 2 is introduced as an age tracer and used in combination with water age estimates determined from CFC-12 data. CO 2 and CFC-12 tracer ages constitute a very powerful pair for constraining the shape of TTDs. The highest concentrations of DIC ant appear in the warm and well-ventilated Atlantic water that flows into the region from the south, and concentrations are typically lower moving west into the colder Arctic surface waters. The depth distribution of DIC ant reflects the extent of ventilation in the different areas. The Nordic seas DIC ant inventory for 2002 was constrained to between 0.9 and 1.4 Gt DIC ant , corresponding to ∼1% of the global ocean DIC ant inventory. The TTD-derived DIC ant estimates were compared with estimates derived using four other approaches, revealing significant differences with respect to the TTD-derived estimates, which can be related to issues with some of the underlying assumptions of these other approaches. Specifically, the Tracer combining Oxygen, inorganic Carbon and total Alkalinity (TrOCA) method appears to underestimate DIC ant in the Nordic seas, the DC* shortcut and the approach of Jutterström et al. (2008) appear to overestimate DIC ant at most depths in this area, and finally the approach of Tanhua et al. (2007) appears to underestimate Nordic seas DIC ant below 3000 m and overestimate it above 1000 m.

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Section: Discussionmentioning

confidence: 99%

Section: Anthropogenic Co 2 Distributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nordic seas transit time distributions and anthropogenic CO₂

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“…Eldevik et al (2009 found different results for the DSOW in Denmark Strait itself ( $671N). Hardly any correspondence was seen between the strong freshening at $601N, reported by Dickson et al (2002), and the DSOW in Denmark Strait where the salinity was dominated by an quasi oscillation with a dominant $ 12 year time scale, and a trend of only À0.033 over a the period 1950(Eldevik et al, 2009.…”

Section: Introductionmentioning

confidence: 96%

“…Sarafanov et al (2010) who studied the mean properties of a density defined DSOW, found that in the 1990s and early 2000s the salinity and temperature of the DSOW showed an irregular behaviour without any significant trend. They found some suggestions for an increasing DSOW salinity for the period -2007. Eldevik et al (2009 found different results for the DSOW in Denmark Strait itself ( $671N).…”

Section: Introductionmentioning

confidence: 99%

Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weekly time scales

Aken

Jong

2012

Deep Sea Research Part I: Oceanographic Research Papers

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. a b s t r a c tData in temperature and salinity from near-bottom layer of Denmark Strait Overflow Water in the Irminger Sea near 601N are presented. These are hydrographic section data from data archives, literature, and CTD observations along the former WOCE AR7E line, as well as data from continuous measurements at two locations. For both salinity and temperature, hydrographic variability was present at all time scales that could be analysed, from multi-decadal to weekly. A mechanistic explanation for the primal cause of the hydrographic variability is still lacking. The direct cause of the observed variability has to be sought in variations of the properties of the source water types involved in the overflow across the sill in Denmark Strait, variations in the mutual ratios of these source water types, and in inhomogeneities in the DSOW layer. The strongest changes occurred at the longest time scales, as is often found for ultimately randomly forced geophysical time series. However, a significant annual cycle of the DSOW, not reported before, was observed at the foot of the East Greenland continental slope, likely a deterministic contribution to the hydrographic variability signal.

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Advective and atmospheric forced changes in heat and fresh water content in the Norwegian Sea, 1951–2010

Mork

Skagseth

Ivshin

et al. 2014

Geophysical Research Letters

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Climate variability in the Norwegian Sea was investigated in terms of ocean heat and fresh water contents of Atlantic water above a reference surface, using hydrographic data during spring 1951-2010. The main processes acting on this variability were examined and then quantified. The area-averaged water mass cooled and freshened, but a deepening of the reference surface resulted in a positive trend in the heat content of 0.3 W m À2 . Air-sea heat fluxes explained about half of the interannual variability in heat content. The effect of the advection of Atlantic and Arctic waters on the variability varied with time, apparently due to large-scale changes in the ocean circulation. The data are consistent with the explanation that changing wind patterns caused buffering and then release of Arctic water in the Iceland Sea during the late 1960s to early 1970s, and this caused large hydrographic changes in the Norwegian Sea.

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Observed sources and variability of Nordic seas overflow

Cited by 172 publications

References 27 publications

Nordic seas transit time distributions and anthropogenic CO₂

Nordic seas transit time distributions and anthropogenic CO₂

Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weekly time scales

Advective and atmospheric forced changes in heat and fresh water content in the Norwegian Sea, 1951–2010

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Observed sources and variability of Nordic seas overflow

Cited by 172 publications

References 27 publications

Nordic seas transit time distributions and anthropogenic CO2

Nordic seas transit time distributions and anthropogenic CO2

Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weekly time scales

Advective and atmospheric forced changes in heat and fresh water content in the Norwegian Sea, 1951–2010

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Nordic seas transit time distributions and anthropogenic CO₂

Nordic seas transit time distributions and anthropogenic CO₂