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

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whole draft of the iceberg. However, wind also plays an important role, either
directly or indirectly.
Iceberg sources
Glaciers are numerous in West Greenland; however, the productive glaciers
which produce the most and the largest icebergs are Jakobshavn Isbræ (Ilulissat),
Disko Bay western Greenland and Ittoqqortoormiit, eastern Greenland.
In general, icebergs occur in West Greenland waters between 60° and
72° N, with some exceptions, e.g. low iceberg concentrations off Sisimiut. In
Disko Bay, hundreds of icebergs are present throughout the year (Fig. 3.3.4)
(Valeur et al. 1996, Karlsen et al. 2001).
Most of the icebergs found near assessment area are formed from East
Greenland glacial outlets. Large annual variation in the number and size of
the icebergs rounding Cape Farewell and transported all the way up to
Nuuk and Maniitsoq with the West Greenland current (Nazareth &
Steensboe 1998, Buch 2000, Karlsen et al. 2001). Occasionally, many small
icebergs and bergy bits are calved in the southwest Greenland fjords, however
these have a short life span due to melting and rarely affect ocean areas
(Karlsen et al. 2001).
Iceberg drift and distribution
On a large scale the basic water currents and drift of icebergs in the Davis
Strait are fairly simple. There is a north-flowing current along the Greenland
coast (West Greenland current) and a south-flowing current along Baffin Island
and the Labrador coast (Baffin Island current), giving an anti-clockwise
drift pattern (Fig. 3.3.4). However, branching of the general currents causes
variations, and these can have a significant impact on the iceberg number
and their residence time. Thus, the distribution of icebergs in the area 63º to
68º N is influenced both by the north going West Greenland current and the
south going Baffin Island current and the interaction between them. Thus,
the iceberg drift mainly responds to the surface circulation of these two current
patterns (Karlsen et al. 2001).
Most of the icebergs found near the Fyllas Banke area are from the East
Greenland glaciers. Occasionally, East Greenland icebergs under the effects
of wind and the absence of the Irminger Current (part of the West Greenland
Current) drift westwards across the southern Davis Strait to the coast of
Labrador and Baffin Island. There, they join the main stream drifting southwards.
Distribution and density of icebergs are also controlled by the presence of
multi-year sea ice (Storis), since icebergs drifting within the Storis are prone
to lower melting rates and less deterioration from wave/swell action
(Karlsen et al. 2001, Hansen et al. 2004). The bathymetry is another factor determining
the variability of icebergs south of the Fyllas Banke area, since the
continental slope being particularly steep makes it a shallow water region.
This underlying bathymetry formats eddies (i. e. a circular and counter current
motion from the main water flow) creating instability in the Irminger
Current, resulting in westward branching of the current. Therefore, the largest
north-going icebergs will probably ground before reaching into certain
shallow areas or branch off to the western side of the Fyllas Banke area
(Nazareth & Steensboe 1998, Hansen et al. 2004).