Geology Reference
In-Depth Information
Figure 11.9
CIS Radarsat image analysis chart in the Gulf of St. Lawrence issued on 17 February 2000. The chart
was created from two consecutive frames of Rdarsat‐1; one of them is shown in the inset. The egg codes are
shown on the right side of the chart (interpretation of the egg code is presented in Figure 11.5). (For color detail,
please see color plate section).
Figure 11.1 except the Arctic region. They are generated
weekly but sometimes biweekly. The frequency of the
charts has increased over time for the Arctic regions.
Originally, they were generated monthly over winter sea-
sons only. The frequency was increased to twice a month
to fulfill demands of the International Polar Year in 2006.
Since the fall of 2011, the Arctic regional charts have
been issued weekly throughout the entire year. The charts
serve as a historical record of sea ice. They represent sea
ice conditions for the day specified on each weekly chart
(usually Monday). Each chart represents the best esti-
mate of sea ice conditions on that day. Files are available
for distribution via ftp. They are presented in “tar” for-
mat, which combines the regional shape file (encoded in
SIGRID‐3 format) and associated metadata file (in xml
format). An example of a regional ice chart of the eastern
Arctic is shown in Figure 11.10. The chart represents ice
conditions on Monday 5 January 2015, but the informa-
tion is supposed to be valid for the entire week.
In addition to their use for short‐ and medium‐term
planning for marine operations, regional ice charts are also
used as input to the Global Digital Sea Ice Data Bank.
This is a joint project between the World Meteorological
Organization and the Intergovernmental Oceanographic
Commission. It started in 1989 in support of global cli-
mate monitoring, research, and prediction, as well as spe-
cialized services. Its primary objective is to implement a
consolidated data bank of digital sea‐ice information. The
Canadian Ice Service has developed a digital database of
sea ice maps from its weekly regional ice charts since 1968.
It is available free of charge to the scientific community.
The database has proven to be a valuable tool for climate‐
related Arctic ice and engineering studies that require sta-
tistical information on ice conditions.
Agnew and Howell
[2007] used the digital charts to verify ice concentration
retrieved from passive microwave observation.
Howell et al.
[2008b] used them to estimate the evolution of MY sea ice
in the western Canadian Arctic Archipelago between 1968
and 2006.
Tivy et al.
[2011] found another use to identify
trends and variability in Arctic summer sea ice.
It should be noted that the use of any chart product
from CIS is more favorable when the purpose is to
