Lines are About 3.1m Apart
Distance from ASTRO Building (m)
Figure 22. Plan view of the survey run between the ASTRO building and the elevated dormit-
ory. Survey lines begin at the edge of the ASTRO building and terminate at approximately 800
m, about 10 m short of the base of the dormitory. Average survey line spacing is in meters. Dots
indicate radar targets with depths in meters indicated.
mond with a Y carved into it is wired to the bam-
penetration may be limited to less than about 20 m
boo. The pole was placed with 2.89 m of its length
by their lower power. Operation of the tape re-
corder and control unit outside the tracked vehicle
above the snow surface.
was limited by the cold weather, which shortened
Active and refrozen sewage sumps south of
the usable battery life from 3.5 to about 2 hours.
the dome were found, but the radar did not detect
their full lateral extent as found in the past by oth-
er methods. These sewage sumps are well isolat-
ed from the water well. Poor detection of their
extent is probably attributable to the low reflec-
Annan, A.P., W .M. Waller, D.W . Strangway, J.R.
tivity of frozen sewage, loss of signal strength at
Rossiter, J.D. Redman and R.D. Watts (1975) The
depth, and loss of imaging ability because of the
electromagnetic response of a low-loss, 2-layer, di-
data compression needed to accommodate the
electric earth for horizontal electric dipole excita-
migration algorithm. Improved imaging of sub-
tion. Geophysics, 40(2): 285298.
surface structures near the dome would require
Annan, A.P. and J.L. Davis (1976) Impulse radar
software that accommodates at least twice as
profiling in permafrost. Radio Science, 11(4): 383
many scans (127) for the migration aperture. Suc-
cessful imaging of unfrozen sewage at depth in
Arcone, S.A. (1991) Dielectric constant and layer-
firn at McMurdo station is discussed in Arcone et
thickness interpretation of helicopter-borne short-
Debris just west of the skiway along the tunnel
dry river-ice sheets. IEEE Transactions on Geoscience
route initially proposed between ASTRO and the
and Remote Sensing, 29(5): 768777.
main station appears to be large and extensive.
Arcone, S.A. (1995) Numerical studies of the radia-
The tunnel should be routed just north of this
tion patterns of resistively loaded dipoles. Journal
area. A few objects exist in the snow along this
of Applied Geophysics, 33: 3952.
new route, but a tunnel route can be found
Arcone, S.A. and A.J. Delaney (1987) Helicopter-
among them with the help of radar.
borne short-pulse radar profiles of river-ice sheets
The GPR was sensitive to many subsurface
in Alaska. Journal of Glaciology, 97(1): 333341.
changes in material properties, including con-
Arcone, S.A., E.F. Chacho, Jr. and A.J. Delaney
trasts in firn density caused by traffic. Distorted
(1992) GPR detection of unfrozen water in the Sag-
snow layers around sewage sumps were clearly
avanirktok flood plain, Alaska. Water Resources
visible. We did not experience any radio interfer-
Research, 28(11): 29252936.
ence, but the radar clutter of surface and near-
Arcone, S.A., A.J. Delaney and W . Tobiasson (1994)
surface targets would have precluded interpreta-
Subsurface radar investigations at the Pegasus ice
tion of some records had we not had advance
runway and Williams Field, McMurdo Station,
knowledge of the approximate location and
Antarctica. USA Cold Regions Research and Engi-
depth of features of interest. Future investiga-
neering Laboratory, CRREL Report 94-12.
tions to a depth of about 30 m should use a 400- to
Arcone, S.A., D.E. Lawson and A.J. Delaney (1995)
600-MHz transducer. Higher frequencies for
Short pulse radar wavelet recovery and resolution
greater resolution are available, but their depth of
of dielectric contrasts within englacial and basal