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

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from the inner parts of the Godthåbsfjord (Rignot & Kanagaratnam 2006).
The extent to which the increased freshwater input from the fjord systems
affects the characteristics of the West Greenland Current is currently unknown.
3.3.1 The West Ice and drift patterns
The ice conditions between 60° and 71° N are primarily determined by the
north- or northwest-flowing West Greenland Current bringing in relatively
warm water and the effects of the cold south-flowing Baffin Island Current.
Ice starts to form in the open water in the northern Baffin Bay in September
when the amount of West Ice (first year ice) in the Davis Strait and Baffin
Bay is at the lowest level. In the following months, ice cover increases steadily
from north to south reaching a maximum in late winter, usually in March,
after which it decreases (Nazareth & Steensboe 1998, Buch 2000, 2002,
Hansen et al. 2004). The relatively warm West Greenland Current delays sea
ice formation in the eastern Davis Strait and results in an earlier breakup of
the sea ice than in the western parts. There is therefore always more ice cover
in the western than in the eastern half of Baffin Bay (Fig. 3.3.1). The Baffin
Island Current conveys large amounts of sea ice from Baffin Bay to the Davis
Strait and Labrador Sea, especially during the winter and early spring
months. During this period sea ice normally covers most of the Davis Strait
north of 65° N, but not areas close to the Greenland coast. Here, a flaw lead
(open water or thin ice) of varying widths often appears between the shore
and the offshore parts of the fast- and drift ice as far north as latitude 67° N.
South of 65°- 67° N, sea ice-free areas dominate throughout the year. The
eastern part of the Davis Strait, south of Disko Island, is free of sea ice during
this period (Fig. 3.3.1 and 3.3.2), whereas drifting ice dominates to the
west and north. The area northwest of the Fyllas Banke area is normally free
of West Ice from early May until early January (Valeur et al. 1996, Nazareth
& Steensboe 1998).
Small amounts of multi-year ice of Arctic Ocean origin drift to the western
parts of the area from Lancaster Sound or Nares Strait; however, the multiyear
ice from these waters does not usually reach the West Greenland
shores. At the end of the freeze-up season, first-year ice in the thin and medium
categories dominates in eastern parts (up to about 100 km from the
Greenland coast). The western and central parts of the Davis Strait are dominated
by medium and thick first-year ice categories, mixed locally with
small amounts (1-3 tenths) of multi-year ice (Nazareth & Steensboe 1998)
(Fig. 3.3.1).
The local drift is to some extent controlled by the major surface current systems,
the West Greenland Current and Baffin Island Current; however, the
strength and direction of the surface winds also affect the local drift of sea
ice, especially in the southern waters.
Under normal conditions the multi-year sea ice (Storis) drifts to the Cape
Farewell area in December/January depending on the low pressure system
of the North Atlantic Ocean. In spring and summer, the low pressure system
normally weakens and the Storis drift into Northeastern Labrador Sea or
North-westward along the West Greenland coast. However, on average
Storis drifts north of 63º N every second year, but the amount and presence
of the Storis varies between these years. Storis has never been observed
north of 63º N earlier than late February (Hansen et al. 2004).