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30 SAMC
o
T • Annual report 2012
the sea current drag force, wind drag force, Coriolis
force and wave force.
To model iceberg drift in broken ice, SAMCoT PhD
candidates Renat Yulmetov and (others) are introduc
ing additional terms related to ice force acting on an
iceberg. These complex calculation procedures require
more sophisticated models that will incorporate inter
action between ice floes and an iceberg. Ice floes and
icebergs will be treated as distinct rigid bodies having
their own shape and moments of inertia. The interac
tion between them is integrated for each time step in
the model. By analysing the positions of all ice floes, we
should be able to apply special algorithms to determine
which of the icebergs are on a collision course with a
structure. To those that are predicted to collide we apply
additional contact forces, depending on their rheology,
relative velocity and positions (Fig. 25).
Contact detection is performed by a special research
module, which is an open source project. Contact integra
tion is performed separately by researchers at Matlab.
After calculating contact forces on the iceberg, we apply
that data together with other force data to calculate
iceberg motion for every time step.
Full-scale data is very important for the current study
to validate the numerical models. In this regard, the
SAMCoT specialized research team has deployed
several Ice Tracking Drifters on ice floes and icebergs
in the Barents and Greenland seas (Fig. 26). The track
ers determine and save their GPS position six times
per hour and then send the coordinates through the
Iridium network for analysis. The drift analysis predicts
trajectories, velocities, curvature of trajectory, and
drift velocity spectrum of the icebergs hosting the Ice
Tracking Drifters.
Two trackers were deployed on one iceberg and an
additional tracker was deployed on an adjacent ice floe
to compare the drift of the iceberg and the sea ice. We
analyzed the rotation of the iceberg and the relative
motion of the broken ice field. The relative motion was
proven to be very slow, having relative drift speed. The
relative motion occurred repulsively, during changes in
the drag force direction.
Fig. 2. Schem tic presentation of the contact forces between an iceberg and a circular ice floe.
Fig. 25. Schematic presentation of the contact forces
between an iceberg and a circular ice floe.
Fig. 26. Icebergs in the waters northeast of Greenland dur-
ing the Oden cruise 2012: Left) iceberg drifting in broken ice;
Right) Deployment of trackers; two trackrs (B117, B118) were
deployed 173 m apart on a single iceberg and tracker B119
was deployed on an adjacent ice floe 304 m away from B118.