Table 4. Meteorological data.
Temperatures (C)
Pressure
RH
WS
WD
(m s1)
Date
Time
Gnd
Snow
0.01 m 0.1 m
0.3 m
1m
1.4 m
2m
(mb)
(%)
(deg)
16 Feb
1630
3.4
3.4
3.9
4.2
4.4
4.2
3.5
4.5
963.6
94
3.3
201
16 Feb
1700
3.3
3.4
4.0
4.2
4.4
4.2
3.5
4.4
963.8
93
4.0
209
16 Feb
1730
3.3
3.4
5.2
5.0
5.2
5.0
3.7
4.9
963.9
92
3.9
207
16 Feb
1800
3.3
3.4
5.4
5.1
5.3
5.2
4.1
5.1
963.9
92
3.0
203
16 Feb
1830
3.3
3.4
5.5
5.1
5.4
5.3
4.4
5.2
964.0
92
2.7
222
16 Feb
1900
3.3
3.4
5.5
5.2
5.5
5.4
4.6
5.3
964.0
93
3.0
195
17 Feb
1100
2.7
2.7
1.8
1.2
1.3
0.8
0.0
1.5
971.1
80
3.1
267
17 Feb
1130
2.7
2.7
1.9
1.1
1.1
0.8
0.3
1.4
971.5
80
3.5
311
17 Feb
1200
2.7
2.7
2.2
1.7
1.8
1.5
0.2
1.7
971.5
81
5.1
306
17 Feb
1230
2.6
2.6
1.2
0.7
0.7
0.2
0.1
1.4
971.8
76
5.3
286
17 Feb
1300
2.6
2.5
2.2
1.5
1.7
1.2
0.4
1.4
971.8
76
4.5
302
17 Feb
1330
2.5
2.5
2.5
1.6
1.6
1.2
0.7
1.6
971.7
74
6.4
256
17 Feb
1400
2.5
2.4
1.2
0.3
0.1
0.3
0.9
1.2
971.8
74
4.7
272
snow pit examined on 18 February revealed the
deviation of the values were computed and re-
presence of a thin wind crust at the top underlain
corded every 30 minutes. The meteorological data
by rounded snow crystals with a layer of depth
recorded on 16 and 17 February 1988 during the
hoar at the bottom (Table 5).
seismic and acoustic array experiments discussed
in this report are tabulated in Table 4. Two frost
tubes were installed at the site in January: one was
3.4. Array description and recording procedures
located 5 m north of the met station in a topo-
All the waveform data were digitally recorded
graphic high, and the second was located 10 m
by a Geosource DSS-10A system on 9-track mag-
netic tape at 1600 bpi in the SEG B format. The
south of the met station in a topographic low. The
recording system has a dynamic range of 90 dB
elevation difference between the two was 0.95 m.
and a bandwidth from 3 to 500 Hz at a sampling
The snow depth at the first frost tube was 0.14 m,
rate of 2 kHz. Mark Products L-15B vertical- and
and frost depth exceeded the depth of the tube
horizontal-component geophones with a resonant
(0.775 m) for all of the February readings. On 16
frequency of 4.5 Hz and a sensitivity of 32 V m
February, the snow depth at the second tube was
s1 were used to detect the ground motion. Globe
0.18 m and the frost depth was 0.60 m. Snow
depths at the site during these experiments ranged
100C low-frequency microphones with a sen-
sitivity of 2 V Pa1 were also used as sensors. The
from 0.14 to 0.20 m in most locations. The snow
had been on the ground for some period of time. A
geophones and microphones were placed in an 18-
Table 5. Snow characterization, pit 2, at 1020 on 18 February 1988.
Tempera-
Crystal
Depth
Density
ture
size
(C)
(kg m3)
Layer
(mm)
index
(mm)
Crystal type
1
0
3.5
Wind crust (irregular, broken
crystals), planar dendrites
1
120
3.5
60
0.5
Rounded, often branched
35
150
5.0
5
0.5
Rounded, often branched
85
210
6.5
10
0.5
Rounded, often elongated
2
115
5.0
0
2.5
Depth, hoar, angular,
stepped grains
140
160
4.5
2.5
Depth, hoar, angular,
stepped grains
165
4.5
2.5
Depth hoar, angular,
stepped grains
14
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