Geology Reference
In-Depth Information
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Figure 10.48
Eulerian representation of ice motion (left) and Lagrangian representation (right). In the former
the ice motion between the two dates is determined at fixed grid points and in the latter both the velocity and
the grid cell deformation are tracked for a period of time.
10.7.3. Ice Tracking Algorithm from the Canadian
Ice Service
and approached 3 km/h at some spots in July. The RMSE
of the calculated displacement from Tracker was 3.8 km
in winter/spring and 6.8 km in summer/fall. The large
errors probably reflect the dynamic ice conditions of
northern Baffin Bay relative to the central Arctic Ocean.
The ice motion was validated using in situ ice beacons.
The Tracker algorithm was replaced by a more advanced
algorithm developed by Komarov and presented in
Komarov and Barber
[2013]. The system, called Canadian
Ice Service-Automated Sea Ice Tracking System (CIS‐
ASITS), has been operationally used at the CIS of
Environment Canada to initiate and verify ice forecasting
models. It has also been used so far in a couple of studies
to estimate the exchange of sea ice between the Arctic
and the Canadian Arctic Archipelago (CAA).
Wohllebern
et al
. [2013] used it to study the flux of MY ice from the
Arctic Ocean through the Queen Elizabeth Islands (QEI)
in the Canadian Arctic. This is important because MY
ice moves into the Northwest Passage and becomes
hazard to marine traffic. The study focused on one of the
main gateways for the MY ice flow, which is the Prince
Gustaf Adolf Sea. It concluded that major ice influxes
through the sea occurred as a series of wind‐driven pulses
at rates of approximately 1%-2% of the wind speed.
Howell et al
., [2013a] also used CIS‐ASITS to estimate
the sea ice flux between the Arctic Ocean and QEI from
1997 to 2012 for the months of May-November. They
found that the inflow of MYI into the QEI could be
In 1994 an ice motion tracking algorithm was devel-
oped by Noetix Research Inc. in Ottawa under a contract
awarded by the CIS. It was originally designed to track
ice motion in AVHRR images because of their frequent
coverage. However, it has been used more against
Radarsat images to track ice motion between selected
areas for research and operational purposes. The system
is formally called Ice Tracking Algorithm but it is known
as the Tracker. It mimics the first version of the GPS;
namely using the MCC technique to produce Eulerian ice
displacement and motion maps. Details of the system are
presented in
Heacock et al
. [1993]. The system was used
operationally at CIS rather occasionally. [
Agnew et al
.,
1997, 1999] used it to generate ice motion maps in the
Arctic from passive microwave data.
Wilson et al
. [2001]
applied it to validate the ice motion in the northern Baffin
Bay and the North Water polynya region. The study
developed initial insights into relations between derived
ice motion and latent and sensible heat mechanisms in
the polynya. However, due to the featureless surface of
new ice types, the Tracker algorithm could not trace these
ice types, which constitute a considerable part of the ice
cover in polynyas. Results from this research indicated
that the ice moved at a speed of less than 0.72 km/h (head-
ing southward) during the winter months (January-April)
of 1998. The speed increases gradually during the spring
