Environmental Engineering Reference
In-Depth Information
4.2 ADDITIONAL MEASUREMENTS
Depending on the site conditions and the needs, priorities, and budget of the moni-
toring program, additional sensors may be included to measure vertical wind speed,
high accuracy temperature (for determining vertical temperature gradients), relative
humidity, barometric pressure, and solar radiation. Table 4-3 lists the nominal specifi-
cations for these sensors; the measurement parameters associated with each sensor are
summarized in Table 4-4. Bear in mind that each additional instrument requires power,
and there are limits to the number of instrument channels supported by data loggers.
4.2.1 Vertical Wind Speed
In complex terrain (defined by the IEC as having a slope of more than 10% within
a distance of 20 times the hub height from turbines (4)), it is recommended that
anemometers capable of measuring the vertical wind speed be used in conjunction
Table 4-3.
Specifications for optional sensors
Vertical
High
Barometer
Pyranometer
propeller
accuracy
(atmospheric
Specification
(solar radiation)
anemometer
temperature
pressure)
−
40 to 60
◦
C 94-106 kPa (see
level
equivalent)
0-1500 W/m
2
Measurement range
−
50 to 50 m/s
Starting threshold
N/A
≤
1
.
0 m/s
N/A
N/A
Distance constant
N/A
≤
4
.
0m
N/A
N/A
Operating temperature
range,
◦
C
−
40 to 60
−
40 to 60
−
40 to 60
−
40 to 60
Operating humidity
range, %
0-100
0-100
0-100
0-100
≤
0
.
1
◦
C
System accuracy
≤
5%
≤
3%
≤
1 kPa
≤
0
.
01
◦
C
≤
1W/m
2
Recording resolution
≤
0
.
1 m/s
≤
0
.
2 kPa
N/A = not applicable.
Source:
AWS Truepower.
Table 4-4.
Optional measurement parameters
Measurement parameters
Typical monitoring heights
Vertical wind speed, m/s
2 m below top anemometer height
Delta temperature,
◦
C
3 m above ground, and 2 m below top anemometer height
Barometric pressure, kPa
2-3 m above ground
Relative humidity, %
3 m above ground, or 2 m below top anemometer height
Solar radiation, W/m
2
3-4 m above ground
Source:
AWS Truepower.
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