www.sea-technology.com May 2015 / st 45
S
ea ice in both the Arctic and
Antarctic creates a major bar-
rier for ship traffc at high lati-
tudes. The ice areas have to be
avoided by most ships and fshing
vessels. Though icebreakers and
ice-strengthened vessels can move
forward through some ice areas,
they have problems penetrating
the icepack where there is high
ice pressure and concentration.
In January, the Chinese icebreak-
ing research vessel Snow Dragon
(Xue Long in Chinese) was trapped
in thick ice foes after an interna-
tional Antarctic rescue mission,
causing much more attention to
be paid to polar sea ice drift and navigation
safety in polar areas.
Given the movement and potential de-
structiveness of sea ice, conventional in-situ
instruments are limited for oceanographic and
meteorological observations in polar areas.
Although sea ice movement can be estimated
approximately by buoys drifting on the ice
cover, as well as drifting ice stations or ships,
these approaches can only provide data of
low-spatial resolution with poor coverage. Re-
mote sensing imagery is clearly an attractive
alternative method. Since the estimation of
sea ice drift requires sequential satellite imag-
es, separated by typically a few days at most,
only satellite images acquired by wide-swath
sensors with high data frequency are favorable
for the application. Remote sensing imagery
with sun-synchronous polar orbit has become
an important technical means to monitor sea
ice movement at high latitudes. The methods
using visible or infrared imagery are not ideal
because of instances of cloud cover and polar
night, and the spatial resolution of passive mi-
Sea Ice Drift Monitoring
Based on SAR Imagery
Determining Polar Ice Drift With High-Resolution Satellite Images
By Dr. Hequan Sun • Dr. Jiguang Wang • Zhigang Zhang
(Top) Graphic user interface of
the SAR-ICE software. (Bottom)
SAR images of Antarctic ice gen-
erated by Radarsat-2.