The Davis Strait - DCE - Nationalt Center for Miljø og Energi

3.2.3 The coasts
The coastal zone between 62º-68º N is dominated by bedrock shorelines with
many skerries and archipelagos. In sheltered areas small bays with sand or
gravel are found between the rocks. Sandy beaches are found in the Marraq-
Sermilik area and in the vicinity of the Frederikshåb Isblink glacier, where
there are extensive sandy beaches and barrier islands (Mosbech et al. 1996b).
3.3 Ice conditions
Sea ice of the following main types occurs in the Davis Strait: ‘Storis’, which
is mainly multi-year drift ice of polar origin carried to Southwest Greenland
by the East Greenland Current; and the ‘West ice’, which is mainly first-year
drift ice formed in Baffin Bay and the Davis Strait. Sea ice is normally present
in the Davis Strait from November to mid-summer. However, the waters
south of Nuuk are normally free of sea ice but occasionally covered for a
short period of time in late winter. During the spring and early summer
months, multi-year sea ice can drift into the area (Nazareth & Steensboe
1998, Buch 2000, Karlsen et al. 2001, Buch 2002, Hansen et al. 2004). The Davis
Strait experiences strong annual variability in sea ice extent and concentration,
primarily driven by wind and current patterns, and low winter temperatures.
The variability in distribution of the sea ice is primarily determined
by the annual North Atlantic Oscillation (NAO) index, as explained
above. The annual NAO variability determines the current pattern of the
Davis Strait which influences the north-south extent of sea ice and the position
of the sea ice edge (Buch 2000, 2002, Heide-Jørgensen et al. 2007b).
The assessment area is influenced by the warm West Greenland Current,
which is an offshoot of the Gulf Stream. The warm, north-flowing West
Greenland Current creates open water in winter along the Southwest Greenland
coast, and inhibits ice formation close to the Greenland West coast as
far as to 67º N (Nazareth & Steensboe 1998, Buch 2000, 2002, Hansen et al.
2004). This warm flowing current has such an impact in the area that it usually
results in earlier breakup of the sea ice in the eastern part than in the
western part of the Davis Strait. During winter and early spring West ice is
conveyed south along Baffin Island to Davis Strait and Labrador Sea. At the
end of the freeze-up season, first year sea ice usually dominates in the eastern
part of the Davis Strait, while the western and central parts of the Davis
Strait are dominated by thicker first year sea ice mixed with smaller parts
(1-3 tenths) of multi-year sea ice. The northwestern part from Fyllas Banke is
usually free of West ice from early May until early January and the southeastern
part is free from mid-April until late January (Nazareth & Steensboe
1998).
Sea ice cover has decreased in the Arctic during the past 20 years (Parkinson
2000), both in thickness and extent (Rothrock et al. 1999). This has occurred
much faster than would be expected from natural climate variations
(Vinnikov et al. 1999). Observations based on satellite data from 1979-2007
show a reduction in sea ice cover of 11.4% per decade. This rate is expected
to increase due to a reduction in the albedo effect as multi-year ice disappears
(Comiso et al. 2008 and references therein). In recent years sea ice has
shown high year-to-year variability or reduced extent for limited time periods
in Disko Bay (Hansen et al. 2006), depending on atmospheric cooling
(Buch 2000, 2002, Tang et al. 2004). Evidence exists of increased volumes of
melt water in the fjord systems from the Greenland Ice Sheet as it loses mass
(Velicogna & Wahr 2006, Velicogna 2009), including increased melt water
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