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10
1
10
0
0
2
4
6
8
10
12
14
16
18
20
U
10
, m/s
25
20
15
10
5
0
0
2
4
6
8
10
12
14
16
18
20
t, min
Figure 9.1 (top) 20min-average measured wind profiles for wind speeds of
U
10
=
5
.
1, 10.0, 15.0
and 19
.
8m
/
s, respectively. (bottom panel) One-minute-average wind speeds at the 10m height for
these records. Figure is reproduced from
Babanin & Makin
(
2008
) by permission of American
Geophysical Union
Here, we are mainly interested in the air-side boundary-layer observations. The wind
profile was obtained by means of the anemometer mast with six cup anemometers
logarithmically-spaced from 10m height down to 22 cm above the mean sea level. The
wind directions were measured at 10 and 0
89m heights. The wind probes were Aan-
deraa Instruments Wind Speed Sensors 2740 and Wind Direction Sensors 3590. The speed
sensor provided 1min-average wind speeds and gusts. The accuracy of the wind-speed
measurements is 12% or 0
.
s whichever is greater. Additionally, for redundancy in the
wind-speed and momentum-flux estimates, a Gill Instruments ultrasonic anemometer was
also deployed on the mast and sampled the three-dimensional air velocity at 21 Hz rate.
The capability of the Lake George anemometer-mast measurements is demonstrated in
Figure 9.1
. In the top panel, profiles of the near-surface winds are shown for records of
mean wind conveniently separated by 5m
.
2m
/
s. No significant
or systematic deviations from the logarithmic profile
(3.19)
are evident. Overall, corre-
lation coefficients for the logarithmic profiles were above 99%. Therefore, stratification
/
s: 5.1, 10.0, 15.0 and 19
.
8m
/
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