Geology Reference
In-Depth Information
0.50
Snow cover
0.00
10
9
8
76 5
4
3
21
Station
Old ice of 1981-82
0.50
Old ice - new ice
interface
1. 00
New ice of 1982-83 winter
on 5 April 1983
1. 50
2.00
Ice-water interface
2.50
0
1.2
2.4
3.6
4.8
6.0
7. 2
Figure 5.17
Profile of snow and ice along the experimental
line with 10 stations (marked as 1-10) in Mould Bay on 5 April
1983 [from
Bjerklund et al
., 1985 with changes].
Figure 5.15
Helicopter view of the crack of Figure 5.8 and
associated drainage channels in Mould Bay on 14 July, 1982
from altitude of about 150 m [
Holt and Digby
, 1985, Fig. 3,
with permission from AGU].
changes in the salt content and hence the electrical prop-
erties of the ice. This line of demarcation, therefore,
provides extremely important information on the trans-
mission characteristic of electromagnetic (EM) waves of
the ice cover, especially for long waves. Incident micro-
wave transmitting through the virtually salt‐free SY ice
will be absorbed rapidly soon after penetration through
this interface. It will be shown later that this line of
demarcation also affects transmitivity and reflectivity
of EM waves in the visible range.
The SY ice cover was completely desalinated as shown
in Figure 5.18 for station 3 and Figure 5.19 for station 9
near the two ends of the old ice cover. Since blocks of ice
samples were obtained from station 3, about 2 km from
the eastern shore (approximately around the station 3
of Mould Bay 1981, 1982 experiments), during previous
field laboratory strength tests on YI in October 1981
[
Sinha
, 1984] and mature FY ice in June-July [
Sinha
,
1983b], it was decided to perform strength tests also on
SY ice at this location [Sinha, 1985a, 1985b]. The total
ice thickness at this site was 1.87 m as can be seen in
Figure 5.17. Large blocks of ice for strength tests were
cut with a chain saw. Since the air temperature during this
trip ranged from a minimum of −46°C to the maximum
of −20°C, special care was taken to preserve the integrity
of the ice cores and blocks. The samples were wrapped
with insulation and shock absorbing materials soon
after recovery to prevent damage from sudden temper-
ature changes and also protect from cracking during
the rough snowmobile trip to the field laboratory at the
weather station.
The density profile obtained by slicing a 0.1 m wide
and 0.4 m deep vertical thick section of ice at station 3,
shown in the photograph beside the plots, is illustrated by
Figure 5.16
View of predominantly SY ice cover in Mould Bay
on 31 March 1983 showing surface undulations and a track
made by a snow plough for establishing the experimental line
across the bay (photo by N. K. Sinha, unpublished).
through two complete seasons of growth (to be called
SY ice) varied between a minimum of 0.17 m near sta-
tion 2 and a maximum of about 0.9 m between stations
4 and 6. This was also the region of maximum snow
accumulation. Consequently, the growth of the new,
1GS, ice was expected to be the lowest in this region. The
thickness of the underlying new, 1GS ice (to be called as
FY ice) was found to be the lowest of 1.35 m at station
5. The shore leads consisted of top‐to‐bottom FY ice
with the maximum thickness of about 2.3 m around sta-
tion 10 close to the western shore, which also coincided
with the near absence of snow.
The “old ice‐new ice interface” line in Figure 5.17 is
rough but corresponds to the approximate line of abrupt
