Variability and renewal of Labrador Sea Water in the Irminger Basin in 1991–2004
Labrador Sea Water (LSW) property variations are analyzed using the data from six hydrographic sections occupied in 1991–2004 in the southern Irminger Basin between Cape Farewell and the Reykjanes Ridge. From 1991 to 1996, the LSW layer became steadily colder and fresher...
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Warming and salinification of intermediate and deep waters in the Irminger Sea and Iceland Basin in 1997–2006
Recent intra-decadal changes in temperature and salinity of the Labrador Sea Water and Nordic overflow waters are quantified on the basis of the CTD data from the repeats of the zonal transatlantic section along 60°N carried out in 1997, 2002, 2004 and 2006. The revealed changes, in general, point to a rapid transition...
Warm intrusions in the intermediate layer (150–500 m) of the Black Sea eastern gyre interior
The new CTD data from the R/V Akvanavt 2002 cruise presented and discussed in this study, show that lateral limits of the Bosphorus lens penetration into the Black Sea interior are substantially wider than the earlier observed ones. The data reveal unexpectedly thick warm lenses in the 150–500 m depth range within the eastern gyre of the Black Sea. Thus, we provide observational evidence...
Water mass characteristics in the equatorial North Atlantic: a section nominally along 6.5N, July 2000
In July 2000, a transatlantic conductivity-temperature-depth/hydrographic section was occupied on board the Russian R/V Akademik Ioffe in the northern equatorial region from 9°26′N, 17°22′W to 3°48′N, 47°16′W near the World Ocean Circulation Experiment (WOCE) A06 line. The water mass characteristics and the main features of cross-sectional circulation are reported on the basis of...
Intense warming and salinification of intermediate waters of southern origin in the eastern subpolar North Atlantic in the 1990s to mid-2000s
Recent thermohaline changes in the layer of intermediate waters (IW) advected into the eastern subpolar North Atlantic from lower latitudes are quantified using the data from the repeated transatlantic sections. Positive trends in temperature and salinity in the IW density class at 53°N and 60°N are derived. The unexpectedly high rates...
On the effect of the North Atlantic Oscillation on temperature and salinity of the subpolar North Atlantic intermediate and deep waters
The close relationship between the observed water mass properties and the winter North Atlantic Oscillation (NAO) index (1950–2000s) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale...
Recent changes in the Greenland–Scotland overflow-derived water transport inferred from hydrographic observations in the southern Irminger Sea
Recent decadal changes (1955–2007) in the baroclinic transport of the Deep Western Boundary Current carrying the Greenland–Scotland overflow-derived waters along the East Greenland slope are quantified from a set of hydrographic sections in vicinity of Cape Farewell. The updated historical record shows clear decadal variability (±2–2.5 Sv) with the transport minima in the 1950s and mid-1990s...
The Atlantic Meridional Overturning Circulation and the subpolar gyre observed at the A25-Ovide section in June 2002 and 2004
The horizontal circulation of the subpolar gyre and the Meridional Overturning Circulation (MOC) are investigated here by comparing two snapshots of the North Atlantic as delivered by two hydrographic sections between Greenland and Portugal. The corresponding cruises were carried out in June–July 2002 and June–July 2004 on R/V Thalassa within the framework of the Ovide project. The absolute transports...
Assessing decadal changes in the Deep Western Boundary Current absolute transport southeast of Cape Farewell, Greenland, from hydrography and altimetry
In earlier studies, the decadal variability of the Deep Western Boundary Current (DWBC) transport in the vicinity of Cape Farewell, Greenland, has been assessed from changes in the baroclinic velocities computed from hydrographic data and referenced to 1000 m depth. The main limitation of using such an estimate as an index for the DWBC absolute transport variability comes from the unaccounted for decadal velocity changes...
Cessation and partial reversal of deep water freshening in the northern North Atlantic: observation-based estimates and attribution
Recent decadal salinity changes in the Greenland-Scotland overflow-derived deep waters are quantified using CTD data from repeated hydrographic sections in the Irminger Sea. The Denmark Strait Overflow Water salinity record shows the absence of any net change over the 1980s–2000s; changes in the Iceland–Scotland Overflow Water (ISOW) and in the deep water column, enclosing both overflows, show a distinct freshening reversal in the early 2000s...
The Irminger Gyre: circulation, convection, and interannual variability
In this study 36 hydrographic transects occupied between 1991 and 2007 in the vicinity of the WOCE A1E/AR7E section are used to investigate various aspects of the Irminger Gyre, a narrow cyclonic recirculation in the southwest Irminger Sea. Vertical sections of absolute geostrophic velocity were constructed using satellite and shipboard velocity measurements, and analyzed in conjunction with the hydrographic data and meteorological fields. The Irminger Gyre is a weakly baroclinic feature...
On the cascading of dense shelf waters in the Irminger Sea
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...
Mean full-depth summer circulation and transports at the northern periphery of the Atlantic Ocean in the 2000s
A mean state of the full-depth summer circulation in the Atlantic Ocean in the region in between Cape Farewell (Greenland), Scotland and the Greenland-Scotland Ridge (GSR) is assessed by combining 2002–2008 yearly hydrographic measurements at 59.5°N, mean dynamic topography, satellite altimetry data and available estimates of the Atlantic–Nordic Seas exchange. The mean absolute transports by the upper-ocean, mid-depth and deep currents and the Meridional Overturning Circulation...
Variability of the meridional overturning circulation at the Greenland–Portugal Ovide section from 1993 to 2010
The meridional overturning circulation (MOC) in the North Atlantic transports heat from the subtropics to high latitudes and hence plays an important role in the Earth's climate. A region crucial for the MOC is the northern North Atlantic and the adjacent Nordic Seas, where waters transported northward in the MOC upper limb progressively cool, gain density and eventually sink. Here we discuss the variability of the gyre circulation, the MOC and heat flux as quantified from...
The northern North Atlantic Ocean mean circulation in the early 21st Century
The decadal mean circulation in the northern North Atlantic was assessed for the early 21st century from repeated ship-based measurements along the Greenland-Portugal OVIDE line, from satellite altimetry and from earlier reported transports across 59.5°N and at the Greenland-Scotland sills. The remarkable quantitative agreement between all data sets allowed us to draw circulation pathways with a high level of confidence. The North Atlantic Current (NAC) system is...
Observed basin-wide propagation of Mediterranean water in the Black Sea
Mediterranean water entering the Black Sea through the Bosphorus Strait forms middepth intrusions that contribute to the salt, heat, and volume balances of the sea, ventilate its water column at intermediate depths and restrain the upward flux of hydrogen sulfide from deeper layers. Despite the importance for the Black Sea environment, the circulation of Mediterranean-origin water in the basin is fundamentally underexplored. Here we use hydrographic data collected from...
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