Kipp & Zonen LAS, Instruction Manual

Page: 23 / 75

22
Important: The minimum distance between the upper and lower temperature sensor
should be at least 1.7 m in order to measure a reliable temperature gradient, with the
lower temperature at a height lower than 1m! When the sensors are positioned too
close to each other (or both installed too high) no distinctive diurnal temperature
gradient can be measured along the day. This will lead to misinterpretation of the
atmospheric stability by the EVATION software.
Table 3: Typical sensor height and orientation of sensors in the 4 m mast.
Sensor Typical
Height/depth
Arm Orientation/Direction
1 Wind speed ( u ) ±
4.4 m
U-cross arm -
2 Wind direction (WD) ±
4.2 m
U-cross arm -
3 Antenna
±
3.5 m - To LAS-Receiver
4 Air Temperature (upper
level) (
T
+
)
±
2.7 m
Two-sided cross arm Opposite of radiation sensor
5 Net radiation ( Q* or R
n
) ±
2.7 m
Two-sided cross arm South on N. Hemisphere
North on S. Hemisphere
6 Air Temperature (lower
level) (
T
-
)
±
0.5 m
One-sided cross arm Below upper temperature
sensor (
lower temp. sensor
must be lower than 0.8m! ;
distance between upper and
lower temp. sensor must be
at least 1.7 m!
)
7 Soil heat flux plate 1 ( G
1
or HFP
1
)
0.003 – 0.03 m - At same side of mast as the net
radiation sensor
8 Soil heat flux plate 2 ( G
2
or HFP
2
)
0.003 – 0.03 m - At same side of mast as the net
radiation sensor
9 Air pressure ( P ) - Inside enclosure -
9 Solar panel At the base of
the tower Use extendable arms
and small pins South on N. Hemisphere
North on S. Hemisphere
10 Enclosure for data
logger and power supply
At the base of
the tower - Opposite of solar panel