NOVEMBER 2020 
LIN ET AL. 
3239 
FT 
(a) Data coverage 
edge of the section, centered near 150m, is Irminger Water that 
has recirculated north of the strait (Mastropole et al. 2017; 
Casanova-Masjoan et al. 2020). Near the bottom is the DSOW, 
denser than 27.8 kg m (this isopycnal is highlighted in Fig. 4). 
As noted above, this is a combination of Atlantic-origin 
Dverflow Water (AtOW) and Arctic-origin Overflow Water 
‚ArOW), which is banked up on the western side of the trough 
see also Väge et al. 2011; Harden et al. 2016; Mastropole et al. 
2017). The breakdown between these water masses is ad- 
iressed in the next section. 
Figure 4d shows the mean section of absolute geostrophic 
velocity. This is the first such view of the average, full water 
zolumn velocity structure across Denmark Strait. The strong 
poleward flow in the vicinity of the Iceland shelf break is 
:he NIC, which transports Irminger Water into the Iceland 
Sea. Seaward of the NIIC there are two bands of southward, 
Dottom-intensified flow associated with tilting isopycnals 
s;loping downward from west to east. The stronger band of flow 
:s located on the western side of the deep trough and transports 
the densest DSOW. The second band is situated near the East 
Greenland shelf break. As noted above, the NIJ, separated 
EGC, and shelfbreak EGC all advect water into Denmark 
Strait (Fig. 1). The yearlong mooring dataset across the 
Blosseville Basin used by Harden et al. (2016) revealed that, 
n the mean, the NIT and separated EGC were partially 
merged at that location. Our results demonstrate that, in 
Denmark Strait, these two currents are fully merged and 
correspond to the stronger band of flow in Fig. 4d which 
:ransports the majority of the DSOW. The weaker band of 
low to the west is the shelfbreak EGC. These two distinct 
dands are seen in the most of individual sections. Note, 
nowever, that there is only a slight minimum in flow between 
the shelfbreak EGC and the merged NIJ-separated EGC 
‚Fig. 4d), which indicates that all three branches have com- 
bined to some degree in the narrow strait. 
bh. Partitioning the DSOW transport 
The transport of DSOW (denser than 27.8 kg m *) in the 
„icinity of Denmark Strait has been estimated in many 
;tudies. Harden et al. (2016) reported a yearlong mean 
value of 3.54 + 0.16Sv from the mooring array across the 
Blosseville Basin in 2011-12. Jochumsen et al. (2012) estimated 
‚he value to be 3.40 + 0.60 Sv using one or two moorings in the 
zenter of the strait from 1996 to 2011. This value was later 
ıpdated by Jochumsen et al. (2017) to be 3.20 + 0.50Sv, ac- 
counting for known biases in the near-bottom current mea- 
surements and using a new method developed from extended 
neasurements. In each of these studies the error represents the 
statistical uncertainty based on the length of the time series. 
From the mean section of Fig. 4d, we obtain a transport of 
3.00 + 0.29 Sv (Table 2, where the uncertainty is the instrument 
3rror, as explained above). This is lower than the previous 
3stimates because our mean section only extends —20 km west 
>fthe East Greenland shelf break. Transects that extend across 
:he entire Denmark Strait reveal that DSOW is found far onto 
‘he Greenland shelf, and the limited velocity information there 
‚mplies weak mean flow (Brearley et al. 2012; Jochumsen 
et al. 2012). The Greenland shelf contribution in the model 
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FIG. 4. Mean vertical sections of the 22 occupations of the 
Lätrabjarg transect: (a) data coverage, along with (b) potential 
:emperature (°C), (c) salinity, and (d) absolute geostrophic velocity 
/m s7') overlain by potential density (kg m“) contours. Positive 
negative) velocities are equatorward (poleward). The highlighted 
sopycnal of 27.8 kg m”* is the upper boundary of the overflow 
water. The Iceland shelf is on the east side of the trough (positive 
distance), and the Greenland shelf is on the west side (negative 
distance). Water masses are identified using blue labels. 
‘d) Absolute 
qrostrophie velocity (m =!" 
that our mean view using a smaller number of sections is rep- 
resentative. The warm and salty water on the Iceland shelf is 
the Irminger Water originating from the south (the near- 
surface freshwater at the eastern end of the section is likely 
associated with the Iceland Coastal Current, Logemann et al. 
2013). To the west, the vertically varying temperature and sa- 
linity reflects several water masses. In the upper layer, the cold 
and freshwater, referred to as Polar Surface Water, emanates 
from the Arctic Ocean via Fram Strait (de Steur et al. 2009; 
Hävik et al. 2017a). Beneath this, the warm water at the western 
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