Campbell CR10 PROM, Руководство оператора

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SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
11-2
In an example where the scan rate is 1 second
and the Output Flag is set every 60 minutes,
the standard deviation is calculated from all
3600 scans when the sub-interval is 0. With a
sub-interval of 900 scans (15 minutes) the
standard deviation is the average of the four
sub-interval standard deviations. The last sub-
interval is weighted if it does not contain the
specified number of scans.
There are three Output Options that specify the
values calculated.
Option 0:
Mean horizontal wind speed, S.
Unit vector mean wind direction,
Θ
1.
Standard deviation of wind direction,
σ
(
Θ
1).
Standard deviation is calculated using the
Yamartino algorithm. This option complies
with EPA guidelines for use with straight-
line Gaussian dispersion models to model
plume transport.
Option 1:
Mean horizontal wind speed, S .
Unit vector mean wind direction,
Θ
1.
Option 2:
Mean horizontal wind speed, S.
Resultant mean wind speed, U.
Resultant mean wind direction,
Θ
u.
Standard deviation of wind direction,
σ
(
Θ
u).
This standard deviation is calculated using
Campbell Scientific's wind speed weighted
algorithm.
Use of the Resultant mean horizontal wind
direction is not recommended for straight-
line Gaussian dispersion models, but may
be used to model transport direction in a
variable-trajectory model.
Measured raw data:
S
i
= horizontal wind speed
Θ
i
= horizontal wind direction
Ue
i
= east-west component of wind
Un
i
= north-south component of wind
N = number of samples
Calculations:
Scalar mean horizontal wind speed, S:
S=(
Σ
S
i
)/N
where in the case of orthogonal sensors:
S
i
=(Ue
i
2
+Uni
2
)
1/2
Unit vector mean wind direction,
Θ
1:
Θ
1=Arctan (Ux/Uy)