Campbell Scientific CSAT3B CSAT3B Three-Dimensional Sonic Anemometer - Page 68

Test for Wind Offset

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CSAT3B Three-Dimensional Sonic Anemometer Section 6, Specifications, is another indication that a recalibration is due. To check for wind offset, refer to Section 9.4.1, Test for Wind Offset. 9.4.1 Test for Wind Offset Testing wind offset on a CSAT3B requires creating an environment where there is no wind. Because it is difficult to do this in the field, wind offset data from the CSAT3B should be collected in a field office or the lab. A zero-wind environment can be created with a kitchen waste bin liner. The following steps should be taken to test the CSAT3B for wind offset. 1. Mount the head using the horizontal mount boom (as described in Section 4.1, Hardware Connections, or hang the head from the block that supports the CSAT3B upper and lower arms. Do not lay the CAST3B head on its side or balance it on the transducers, as this will affect its measurements. 2. Cover the CSAT3B head with a medium (13-gallon) kitchen waste bin liner. Close the opening of the liner by folding, taping, or tying, to prevent air from moving in and out of the liner. Temporarily disable the HVAC system in the room, or cover air vents that may cause air drafts to pass by the CSAT3B. Ensure that the liner does not obstruct any of the three CSAT3B sonic paths. 3. Connect the CSAT3B power and communications cable to the datalogger referring to Section 4.2, Communications Connections. Connect to the datalogger with PC200W, PC400, or LoggerNet. 4. Use the real time monitoring graph display to create two graphs. a. On the first graph add the ux and uy wind components and set the y limits from −0.08 to 0.08 as shown in FIGURE 9-3. b. On the second graph add the uz wind component and set the y limits from −0.04 to 0.04 as shown in FIGURE 9-4. c. For both graphs, set Graph Width to 1 minute and Update Interval to 1 second. 58

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CSAT3B Three-Dimensional Sonic Anemometer
Section 6,
Specifications
, is another indication that a recalibration is due.
To
check for wind offset, refer to Section 9.4.1,
Test for Wind Offset
.
9.4.1 Test for Wind Offset
Testing wind offset on a CSAT3B requires creating an environment where
there is no wind. Because it is difficult to do this in the field, wind offset data
from the CSAT3B should be collected in a field office or the lab. A zero-wind
environment can be created with a kitchen waste bin liner.
The following steps
should be taken to test the CSAT3B for wind offset.
1.
Mount the head using the horizontal mount boom (as described in
Section 4.1,
Hardware Connections
, or hang the head from the block
that supports the CSAT3B upper and lower arms. Do not lay the
CAST3B head on its side or balance it on the transducers, as this will
affect its measurements.
2.
Cover the CSAT3B head with a medium (13-gallon) kitchen waste
bin liner. Close the opening of the liner by folding, taping, or tying,
to prevent air from moving in and out of the liner.
Temporarily
disable the HVAC system in the room, or cover air vents that may
cause air drafts to pass by the CSAT3B.
Ensure that the liner does not
obstruct any of the three CSAT3B sonic paths.
3.
Connect the CSAT3B power and communications cable to the
datalogger referring to Section 4.2,
Communications Connections
.
Connect to the datalogger with
PC200W
,
PC400
, or
LoggerNet
.
4.
Use the real time monitoring graph display to create two graphs.
a.
On the first graph add the u
x
and u
y
wind components and set
the y limits from
−
0.08 to 0.08 as shown in FIGURE 9-3.
b.
On the second graph add the u
z
wind component and set the
y limits from
−
0.04 to 0.04 as shown in FIGURE 9-4.
c.
For both graphs, set
Graph Width
to 1 minute and
Update
Interval
to 1 second.
58