Geology Reference
In-Depth Information
Table 1.1
Weather stations in the Canadian Arctic region (currently operational and
decommissioned).
Weather Station
Latitude °N
Longitude °W
Start
End
Territory
Alert
50.583
126.933
1913
2006
Nunavut
Eureka
79.983
85.933
1947
Cont.
Nunavut
Isachsen (closed)
78.783
103.533
1948
1978
Nunavut
Grise Fiord
74.417
82.950
1973
1977
Nunavut
Mould Bay (closed)
76.233
119.333
1948
1997
NWT
Resolute
74.717
94.970
1947
Cont.
Nunavut
Nanisivik
72.983
84.617
1976
2011
Nunavut
Pond Inlet
72.689
77.969
1975
Cont.
Nunavut
Sachs Harbor
72.000
125.267
1955
Cont.
NWT
Holman
70.733
117.783
1941
1969
NWT
Clyde
70.486
68.517
1933
Cont.
Nunavut
The weather stations in the Arctic region (most of them
are in the High Arctic) are listed in Table 1.1. These sta-
tions were established by the Canadian government and
some were operated jointly with the U.S. military. Only
five stations are currently operational: Eureka, Resolute
Bay, Pond Inlet, Sachs Harbour, and Clyde. The locations
of all stations are marked in Figure 1.3. When all stations
were operational, they formed a network for providing
weather services that were considerably significant by
Arctic standards. A detailed historical account of devel-
opment and expansion of meteorological facilities in the
Arctic is given by
Smith
[2009].
properties, as well as the properties of a possible overlaid
snow cover, change in order to maintain a state of ther-
mal equilibrium between the ice and the atmosphere.
The third characteristic is responsible for the floatation
of ice on its melt and therefore moving in response to
wind and oceanic current unless it is shore fast (called
“land fast”) or becomes “grounded” in relatively shallow
waters. Land‐fast ice, however, is subjected to tidal
actions producing cracks, “ice hinges,” and rubbles par-
allel to the shorelines. Sea ice is considered to be the fast-
est global‐scale solid material moving upon Earth's
surface. Given the complex nature of sea ice composi-
tion, its thermal state, and mobility, it is important to
understand the processes involved in its formation and
growth, particularly the desalination and deformation
processes, as well as its decay. This should help to demys-
tify the descriptions found in literature about ice, and sea
ice in particular, as apparently peculiar, bewildering,
confusing, puzzling, baffling, etc.
The heterogeneous and multiphase composition of sea
ice arises because the salts and gases that dissolve in sea-
water cannot be incorporated into the lattice (polycrys-
talline) structure of sea ice. This structure is made up of
pure ice crystals, leaving salts to be included within the
interstices of the solid ice matrix in the form of liquid
brine. Gases are also included in the form of gaseous
bubbles. Other impurities such as microalgae, nonorganic
deposits, and trace elements may also exist. A character-
istic process that follows from this multiphase composi-
tion is the brine drainage (which takes other impurities
with it) into the underlying ocean water. This process
takes place at a rate that depends on the ice permeability
and temperature. It continues throughout the lifetime of
the ice cover, causing the bulk properties of the ice to be
continuously changing.
Since ice exists in nature at temperatures of only a small
fraction below its melting temperature, from the geophys-
ical and materials science point of view it is considered to
1.3. Fascinating nature oF sea ice
Most people living in cold countries, where snow and
ice are part of the most familiar of natural phenomena,
don't think much of scientific importance of these natu-
ral materials. We never realize that the solid state of water
in all of its forms is actually a unique and the most fasci-
nating natural crystalline material. Floating sea ice, in
particular, is a very complex material. It features four
readily noticeable and interesting characteristics. First, it
is a composite material that encompasses three phases of
matter: solid, liquid, and gas, depending upon tempera-
ture. Second, it exists in nature at temperatures very close
to its melting point. In fact, the ice‐water interface at the
bottom of floating ice covers is always at the melting
point. Third, it floats simply because it has lower density
than the density of its melt (i.e., the liquid from which it
solidifies). And snow deposits on floating ice sheets add
to the complexities of the ice regime. Fourth and certainly
the most important aspects of floating ice covers (both
freshwater and sea ice) is the fact that they act like blan-
kets and protect marine life in lakes, rivers, and oceans.
The first two characteristics make floating ice highly
responsive to changes in atmospheric temperature, espe-
cially when it is thin. Its physical and radiometric
