Sustained winds of greater than 5 m/s may
rather than by advected heat. Although wind from
arrive at Pegasus from the calmer "fair weather"
the northerly sector (the direction of open water)
northeast sector in spring. These speeds are suffi-
is more frequent in summer; it occurs less than
10% of the time. Air temperatures above 0C are
cient to initiate drifting, and are a crosswind rela-
tive to the Pegasus runway. The placement of
recorded on many summer days, but rarely
berms, temporary structures, and cargo storage
throughout the day. The warm air observed ap-
should be guided by knowledge that a strong
parently results from adiabatic heating of katabatic
northeasterly can occur on an otherwise fine day.
downflows and probably conserves its subfreez-
Wind from the sectors northwest to southwest
ing frost point while transiting the shelf. This
are rare at Pegasus during winter and spring, and
might cause sublimation of the surface, and pro-
vide transport of water vapor from the site, but
are not strong in summer. This sector should pro-
should not advectively exchange heat with the
vide the least influence to buildings and storage
surface to produce the liquid water sometimes
associated with runway operations.
observed. Wind direction frequency is shown for
Any melting experienced around the runway
the Pegasus South AWS in Figure 21 (main text).
would appear to be a result of solar warming,
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