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to a down-slope horizontal pressure gradient force (Anderson et al.
2005
, Renfrew
and Anderson
2006
), which drives usually shallow drainage flows. These drainage
flows are often too shallow in order to be detected and monitored by ground-based
remote sensing.
Drastic examples of deeper drainage flow are katabatic flows at locations of
Antarctica and Greenland. The domed topography and radiative cooling of the snow
surface make katabatic flows ubiquitous over these regions (Renfrew and Anderson
2006
).
An autonomous Doppler SODAR wind profiling system has been operated over
a 2-year period for the first time. An exemplary result from these measurements is
shown in Fig.
4.40
. The main results are that there is a systematic change in the
300
300
300
12 h
24 h
36 h
48 h
250
250
250
200
200
200
150
150
150
100
100
100
50
50
50
0
0
0
240
260
280
0
2
4
6
8
10
12
60
80 100 120 140 160 180
θ
(K)
wind speed (ms
−1
)
wind direction
300
300
300
250
250
250
200
200
200
150
150
150
100
100
100
50
50
50
0
0
0
−4
−2
0
2
4
6
8
−4
−2
0
2
4
6
8
−0.4 −0.2
0
0.2
0.4
u (ms
−1
)
v (ms
−1
)
w (ms
−1
)
Fig. 4.40
Numerical model results (
thin lines
) and remote-sensing data (
thick lines
,
dashed lines
indicate plus/minus one standard deviation) for katabatic flow over Antarctica. (
a
) potential tem-
perature, (
b
) wind speed, (
c
) wind direction, (
d
) downslope horizontal velocity (
u
), (
e
) across-slope
horizontal velocity (
v
), and (
f
) vertical velocity (
w
). (Renfrew, personal communication, see also
Renfrew and Anderson (
2006
) for further evaluations)
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