340 nway
0/360
Ru
of
End
2
3
Wind Speed (m/s)
270
9
8
7
6
5
4
3
21
20%
9
10
2
90
4
2
3
3
3
4
1
Figure 21. Wind diagrams for the Pegasus
5
South automated weather station (AWS) using
monthly average data for the period 1 January 1993
160 nway
f Ru
nd o
180
to 31 December 1994.
E
transmission of data (Keller 1995). They can be
be necessary to establish the runway flight plate
configured for a variety of measurement inter-
and will suggest the most amenable operating
ests. At the Pegasus site, two AWSs were installed
windows for safe aircraft movement. Wind dia-
in 1991. Data from these monitors, and others on
grams such as shown in Figure 21 should be used
the Ross Ice Shelf, have been studied with the aim
to select the alignment of the runway. If only one
of establishing weather forecasting methodolo-
runway direction will be chosen, it should align
gies for the aircraft operations on the runway
either with the strong wind direction (if strong
(Holmes 1995). Additional analyses of wind data
winds are frequent and any other winds are fairly
from the Pegasus AWS are contained in Appen-
low speed) or with the prevailing wind direction
dix A and resulted in providing the trends shown
(if it is of moderate speed and strong winds are
in Figure 21.
infrequent).
If AWSs are not available, traditional methods
Additional weather information may also be
of data gathering may also be used, where indi-
critical, such as air temperature, net radiation (in-
vidual recording units are installed at the site for
coming and reflected), cloud ceiling and visibil-
each factor of interest. They will need to be ac-
ity. The former two characteristics are important
cessed periodically to retrieve data.
in predicting the integrity of the glacial ice and in
estimating the probability of melt problems. The
Ice temperature profile
latter two factors will be used, together with maps
Ice temperature profiles are the most impor-
of the regional topography and desired aircraft
tant ice information because the mechanical be-
characteristics, to establish minimum safe operat-
havior of ice subjected to loading is strongly
ing conditions. The weather data gathered at this
influenced by its temperature. Vital information
step of the process will allow the probable num-
is the maximum temperature, particularly during
ber of flight days to be determined.
the time period the runways would operate, and
The most convenient means of establishing
its location within the ice column. Subsurface melt-
these data is to install an automated weather
ing may not always be obvious, but it could easily
station (AWS) at the site (Fig. 22). Reliable AWSs
be disastrous for wheeled traffic (Fig. 23). If tem-
now exist and can be monitored via satellite
21
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