International Polar Year 2007–2008 - WMO

Table 2.2-1. Estimates
of volume, heat and
freshwater transports
for the two branches
of the Norwegian
Atlantic Current west
of Svinøy.
156
IPY 20 07–20 08
Fig. 2.2-1.
Distribution of all
173 current meter
moorings and arrays
across the iAOOS
domain in 2008.
Compilation by
Humfrey Melling,
IOS Canada. Small
numerals in red
refer to the number
of moorings in an
array, where these
are too numerous
to distinguish
individually.
(Map: Dickson and Fahrbach,
2010)
The development of the Svinøy section. A
conspicuous highlight of IPY was the first concerted
attack on the ‘other half’ of the northward ocean heat
flux west of Norway. Briefly, although the 12-year timeseries
of transport had by then been recovered from
the inshore branch of the Norwegian Atlantic Current
against the Norwegian Slope, giving some sense of its
local and remote forcing, the offshore branch, passing
north through the Norwegian Sea as a free jet, had
remained unmeasured. In an attack on this critical but
difficult measurement, satellite altimetry, hydrography
and conventional current meter moorings were
combined to calculate the volume, heat and salt
transports of both NAC branches between 1993 and
2007 (Mork and Skagseth, 2009). In the eastern branch
these results agree well with previous estimates (Orvik
et al., 2001), but in the western branch they differ
substantially from SeaGlider based estimates reported
in Mauritzen et al., (2009). During IPY, iAOOS-Norway
continued its aim of “developing the Svinøy Section
into a complete, sustainable, simple and robust
upstream reference system for monitoring Atlantic
inflow towards the Arctic Ocean moved during CTD
and current IPY”, adding conventional moorings,
profiling instruments (MMP CTD/RCM) and SeaGlider
transects. Apart from capturing the successive waves
of warmth that have passed through towards the
Arctic in recent years, this key array continues to
highlight the independence between the flow field
and temperature field, with the flow field dominating
annual variability and with temperature variations
dominating on longer timescales.
Inflow
branch
Eastern 4.2
3.7
Western 3.5
1.4
6.5
Volume
transport
(Sv)
Heat
transport
(TW),
Tref=0oC
133
157 -45
39 -13
Total 7.7
5.1 179 -58
Freshwater
transport
(mSv)
Sref=34.93
Reference
Orvik et al.,
(2001). Mork
and Skagseth
(2009)
Orvik et al.,
(2001). Mork
and Skagseth
(2009)
Mauritzen et
al., (2009)
Orvik et al.,
(2001). Mork
and Skagseth
(2009)