radiometer pairs (Fig. 24) and took measurements
Data analysis
over snow-covered ice, exposed ice, snow with
The data collected should be analyzed and
incorporated mineral dust, and worked snow
stored to establish a historical record of the site
(graded and/or snow processed with the snow-
characteristics. In addition, the data should be
blower). We measured pyranometer output in
compared to the desired operating scenario (air-
volts and recorded only the relative difference in
craft, flight season, cargo demands) to ascertain
reading among the different sites and for the in-
the suitability and the limitations that will be
coming vs. reflected globes.
posed by the chosen site. Clearly, one year's record
will most likely not portray the range of condi-
tions that can occur at the site. Thus, it is valuable
Topography and ice movement
During the first site visit, the topography of
to compare the new data with any historical
characteristic segments of probable runway posi-
records or accounts of the site, or to collect data
tions should have been determined by surveying.
for several years. It is the goal to determine what
It is unlikely that the topography changes much
is the range of temperature, wind and ice behav-
over the course of a year unless the glacier is
ior at the site and to ensure that its properties are
moving quickly. However, it may be wise to re-
either compatible with the planned use or can be
survey one or two segments at significant time
managed to yield a suitable facility.
intervals (e.g., 12 months).
Temperature (air and ice), wind speed, and
More important will be to ascertain the overall
radiation data should be manipulated to produce
movement of the glacier in the region of interest.
plots of variation with time over the span of the
Benchmarks of some sort should be established at
season during the period of planned runway use.
several locations within the site of potential run-
The plots should be scrutinized in any areas where
way positioning. These may be very simple in
the temperatures approach the melting point to
nature, such as a wooden post or plastic pipe
determine the extent of time that could be prob-
buried to a depth of say 1 m and extending above
lematic and the amount of temperature modifica-
the terrain surface about 0.25 m. If the site has any
tion that will be necessary on the runway to ensure
potential for melt problems, the ice for some area
prohibition of melt features. Lateral ice move-
around the benchmark should be covered with a
ment rates and elevation changes should be de-
protective snow cover. The goal is to establish a
termined and plotted on maps to project the life
marker that will move with the glacier but will
expectancy of the runway and to predict the
not experience any change in attitude relative to
amount of work that will be necessary on a sea-
the immediate surrounding ice.
sonal basis to keep the runway level within the
The benchmarks should be exactly located at
standards for the aircraft to be used.
several times over the course of site observation
These data will also be vital in planning the
to establish rate and direction of movement. Lo-
construction process. The extent and timing of
cating the benchmarks may be done either using
each window of opportunity can be identified
GPS or by traditional surveying from a known
from these data and decisions about equipment
fixed point (nearby rock exposure).
needs and single vs. multiyear construction sched-
If cracks or crevasses exist within the region of
ule can be made by matching the tasks to be
interest, they too should be monitored for move-
accomplished to the time available at the site.
ment. This can be accomplished by sketching and
measuring attributes of the features (width, depth,
Making site selection
directional orientation, attitude of subsurface
It is unlikely that a site with no drawbacks will
planes) and by surveying-in (from the bench-
be identified. However, armed with the data and
marks) key features of the crack (e.g., its ends or
knowledge of the task and the potential sites, a
an offset or crack intersection point). Measuring
rational decision can be made as to the best site
crack position and movement frequently during
for a glacial ice runway. Development procedures,
the site observation period would be ideal to de-
equipment needs, and construction schedule will
termine if the crack has active and dormant phases.
most likely be different for any one of the poten-
The farther the cracks are from the most likely
tial sites. Based on the available resources, the
runway position, the less attention they need to
timetable for operations, and the compromises
receive.
necessary for each site, a satisfactory choice can
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