Geology Reference
In-Depth Information
0
0
0
- 4
- 4
- 4
- 8
- 8
- 8
- 12
- 12
- 12
- 16
- 16
- 16
- 20
- 20
- 20
- 24
- 24
- 24
- 28
- 28
- 28
- 32
- 32
- 32
FYI
FYI
FYI
- 36
- 36
- 36
- 40 - 20
- 40
- 40
- 18
- 16 - 14 - 12
Temperature (°C)
- 10
- 8
- 6
02468 0 214 61820
0.4
0.5
0.6
0.7
0.8
0.9
1. 0
Salinity (‰)
Density (g/cm 3 )
0
0
0
- 4
- 4
- 4
- 8
- 8
- 8
- 12
- 12
- 12
- 16
- 16
- 16
- 20
- 20
- 20
- 24
- 24
- 24
- 28
- 28
- 28
- 32
- 32
- 32
MYI hummock
MYI hummock
MYI hummock
- 36
- 36
- 36
- 40
- 40
- 40
- 20
- 18
- 16 - 14 - 12
Temperature (°C)
- 10
- 8
- 6
0.4
0.5
0.6
0.7
0.8
0.9
1. 0
0246810
12
14
16
18
20
Density (g/cm 3 )
Salinity (‰)
Figure 3.16 Temperature, salinity, and density profiles of the top 0.40 m of FY and MY hummock ice obtained
from Lancaster Sound, Canadian central Arctic, in May 1992. These data are representative of 15 cores of FY as
well as MY ice obtained during the same study period [ Shokr and Sinha, 1995].
Timco and Frederking [1996] presented a review of
sea ice density. They reported values of FY ice between
840 and 910 kg/m 3 for the ice above the waterline (in
the freeboard), and 900-940 kg/m 3 for the ice below
the waterline. Alexandrov et al. [2010] also presented
a  collection of earlier measurements on ice densities
for young ice, FY ice, and MY. The freeboard thick-
ness method adopted by Timco and Frederking [1996]
calculates average bulk ice density ρ i , for an ideal ice
sheet with uniform thickness and flat snow cover,
based on the isostatic equilibrium equation, where
input data are ice thickness ( h i ), ice freeboard ( f i )
which can be measured only very roughly, snow depth
( h s ), and snow density ( ρ s ) which actually varies from
the top to the bottom. Water density ρ w is set to
1025 kg/m 3 :
3.4. Volume fracTion of sea ice
consTiTuenTs
In addition to the pure ice crystals, three inclusions coex-
ist in sea ice: brine, solid salts (precipitated inside brine
pockets), and air. Volume fraction of each constituent can
be represented in terms of the ratio of constituent's vol-
ume to the total volume in parts per thousand. For exam-
ple, a brine volume of 10‰ is equivalent to a brine volume
fraction of 0.010. Equations to calculate the volume frac-
tions of these inclusions in FY ice were developed by Cox
and Weeks [1983] based on the sea ice phase diagram devel-
oped by Assur [1958]. The equations are presented below.
Table 3.4 shows the symbols used in these equations.
Salinity is described in terms of mass ratio. Hence, the
salinity of ice ( S i ) and salinity of brine ( S b ) are defined as
f
h
S mm
M
wi ss
(3.14)
ss
sb
(3.15)
i
w
h
si
i
si
 
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