Introduction - Sea Ice: Physics and Remote Sensing - page 4

Sea‐ice‐related information is rather scattered over vast
areas of interdisciplinary fields (e.g., physics, chemistry,
materials science, remote sensing, climate, oceanography,
cryosphere, marine structure and operation, marine biol-
ogy, and, not the least, civil, mechanical, and naval engi-
neering, related to coastal and offshore engineering).
Publications related to the physics and remote sensing are
also scattered and not limited to English‐language litera-
ture. When written in languages other than English, they
obviously become not readily available. Some of the
familiar topics that address physics- and geophysics‐
related areas of ice include Pounder [1965], Paterson
[1969], Hobbs [1974], Untersteiner [1968], Wettlaufer et al.
[1999], Thomas and Dieckmann [2009], and Weeks [2010].
Weeks provided a brief, but very appropriate, historical
background of the European and other explorers and
their explorations of the Arctic and the Antarctic regions
in addition to a comprehensive description of sea ice.
Topics that cover remote sensing of sea ice with some cov-
erage on sea ice physics include Hall and Martinec [1985],
Haykin et al. [1994], Carsey [1998], Jefferies [1998],
Jackson and Apel [2004], Sandven and Johannessen [2006],
Reese [2006], Johannessen et al. [2007], and Comiso [2010].
A few notable review papers on remote sensing of sea ice
include Sandven [2008], Breivik et al. [2010], Kwok [2010],
and Heygster et al. [2012].

Figure 1.2 Sampling of 0.05 m thick sea ice in the Baffin Bay
in May 1998 by the author (Shokr) using a gangway lowered
from an icebreaker (photo by K. Asmus, Canadian Ice Service).

In the last decade or so, Arctic ice has gained extra
attention by the international media and the general
public as well as funding agencies because it is shrinking.
Antarctic sea ice area, on the other hand, remains
essentially the same. Moreover, the Arctic basin connects
the Atlantic and Pacific Oceans. Therefore, if the ice
diminishes or is replaced by thinner (navigable) ice, a
marine navigation route (Northwest or Northeast
Passage) may open. There will be a great positive eco-
nomic impact of this possible scenario, especially for the
countries that will have routes under their sovereignty,
namely Canada and Russia.
Snow cover plays an important role in the thermody-
namic evolution of sea ice. Although it accounts roughly
for only 10% of snow/ice volume, some properties differ
sharply from their equivalent properties of sea ice. Two
familiar examples are the albedo and thermal conductiv-
ity. The albedo of dry snow is above 0.9, which is much
higher than the albedo of bare first‐year sea ice surface
(about 0.52). Increased albedo allows less sunlight to
penetrate the surface. Therefore, snow‐covered ice (with
thick and dry snow) receives less sunlight and so does the
underlying water. More importantly, the thermal conduc-
tivity of the snow is one order of magnitude less than that
of sea ice. This means that snow can insulate sea ice and
slow down its growth. Therefore, the ice will generally be
cooler and that causes a delay of melting in the spring in
spite of reduced thickness.

1.2. Historical synopsis: canada
and tHe arctic

Except for very small areas of persistent ice‐free condi-
tions called polynyas (largest among them is the North
Water Polynya) virtually all the northern oceanic areas of
the second largest country in the world, Canada, freezes
each winter. Historically, however, the Canadian north is
divided loosely into High Arctic and Low Arctic regions.
The High Arctic used to be the “No man's territory” until
about 1958. The High Arctic of Canada is marked by a
circle parallel to the latitude of about 70°N and spans
between the longitudes of 75°W and 125°W. It is defined
as the area consisting of a group of islands known as the
Canadian Archipelago. These islands are separated from
those of the Low Arctic by a wide channel of seawater,
known as the Parry Channel, which includes Lancaster
Sound in the east as shown in Figure 1.3. The width of
this deep seawater channel varies between 40 and 100 km.
It is a hostile environment for human activities because
of the mobile pack ice in many areas. The vast area north
of this widely varying channel was traveled by explorers
from Europe, particularly Norway, only during the late
nineteenth and early twentieth centuries. Naturally, the
Inuit communities of the polar region of Canada concen-
trated their movements in the Low Arctic or the region
south of the Parry Channel. The present‐day settlements