It’s Rough Out There: Comparison of Sea Ice Thickness Measurements from SEDNA 2007
Ice Camp in the Beaufort Sea
Sarah Streeter1, Cathleen A. Geiger2, Jackie Richter-Menge3, Bruce C. Elder3, Steve Arcone3
1Dartmouth College, Hanover, NH
2 University of Delaware, Newark, DE
3Cold Regions Research and Engineering Laboratory, Hanover, NH
ABSTRACT
INSTRUMENTATION
PROFILES
As a WISP student working at CRREL, I primarily spent my time analyzing
data from the Sea-ice Experiment: Dynamic Nature of the Arctic (SEDNA)
project, which took place in April of 2007. The project used many different
methods of instrumentation to measure the depth of the sea ice in the
Arctic. Both a ground electromagnetic induction device and a helicopterborne electromagnetic induction device were used to take measurements
along the same six 1 km survey lines. Although the data from the helicopter
and the ground EM is fairly consistent for first-year ice, there are larger
discrepancies between the two data sets for ice deeper than ~4 m. I spent
my time comparing the two data sets, analyzing where the discrepancies
were greatest, and looking for possible explanations for the differences in
thickness measurements.
LOCATION
Figure 3: Bruce Elder taking ice thickness
measurements using the ground EM-31.
Figure 4: Helicopter with EM Bird in flight over
sea ice in the Beaufort Sea during SEDNA ice
camp (helicopter data courtesy of Christian
Haas, Stefan Hendricks, and Torge Martin).
Figure 5: Sea ice thickness profile of one of the survey lines. The
measurements show good agreement for shallower ice and worse
agreement for thicker ice.
SUMMARY
The data from the SEDNA 2007 ice camp shows good agreement between the ice
thickness profiles from the ground and helicopter-borne EM’s for first year ice, but larger
differences between the two data sets arise in the profiles of thicker, multi-year ice.
Future efforts will focus on applying data gathered from other instruments used at the
ice camp to determine the optimal suite of sensors for ice thickness measurements.
Two possible sources are a ground-penetrating radar (GPR) device and submarine
data. While the GPR data looks promising, the submarine based data presents more of
a problem because it does not follow the same six survey lines, so there is less area
over which to compare the data.
Figure 1: The SEDNA ice camp was located in the Beaufort Sea, north of
Alaska. Generated using Google maps.
Jen’s Ridge
GPR PROFILE
0
Figure 6: A scatter plot of Helicopter EM against Ground EM measurements,
broken down by ice type. The multi year ice deviates the most from the line,
while the first year, not deformed ice deviates the least.
Helicopter Data
2
1
-1
EM Data
6
-2
Camp
3
-3
5
-4
4
-5
-6
-7
Figure 2: Six one km survey lines were used during the SEDNA ice camp.
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1300
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Distance (m)
Figure 7: A thickness profile, from Helicopter and Ground EM measurements, of one of the survey lines overlaid on a profile of the same line from the GPR data. This figure shows that the
GPR data is very promising as an additional data source.
1000
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