Campbell 21X Operator's Manual page 123

SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
There are three Output Options, which specify
the values calculated.
Option
0:
Mean
horizontalwind speed,
S.
Unit
vector mean wind direction,
@1.
Standard deviation
of
wind direction,
o(@1).
Standard deviation
is
calculated using
the
Yamartino algorithm. This option complies
with EPA guidelines for use with straight-line
Gaussian dispersion models to modelplume
transport.
Option
1:
Mean
horizontalwind speed,
S.
Unit
vector mean wind direction.
@1.
Option
2:
Mean
horizontalwind speed,
S.
Resultant mean wind
speed,
U.
Resultant mean wind direction,
@u.
Standard deviation
of
wind direction,
o(@u).
This standard deviation
is
calculated using
Campbell Scientific's wind speed weighted
algorithm.
Use
of
the Resultant mean horizontalwind
direction
is not recommended for straight-
line Gaussian dispersion models, but may
be used to modeltransport direction in
a
variable-trajectory model.
Measured raw data:
Si = horizontal wind speed
@i
= horizontal wind direction
Ue; =
s651-*est component
of wind
Un;= n916-south component of wind
N
= number of samples
Calculations:
Scalar mean horizontalwind
speed, S:
S=(>si)/N
where
in the case of orthogonal sensors:
S,=(Ue,2+Un;2)1/2
Unit vector mean wind
direction.
@1:
where
Ux=(Xsin
@;)/N
Uy=(Xcos
O;)/N
or,
in
the case of orthogonal sensors
Ux=(x(Ue;/U;))/N
Uy=(E(Un/Ui))/N
where
U,=1Ue,2+Un,2) 1
/2
Standard deviation of wind direction,
o(@1),
using Yamartino algorithm:
o(@1)=61s sin(e)[1 +0.1
547
e3l
where,
s=[
1 - ((
U
x)2+
(Uyyzylt
rz
and
Ux
and
Uy
are as defined above.
Resultant mean horizontalwind speed,
U:
U=(Ue2+Un211/2
where
for polar sensors:
Ug=(XS;Sin
@;)/N
1Jn=(XS;Cos
@;)/N
or,
in
the case of orthogonal sensors:
us=(XUei)/N
Un=(tUn,)/N
Resultant mean wind direction,
@u:
@u=Arctan (Ue/Un)
Standard deviation of wind direction,
o(@u),
using Campbell Scientific algorithm:
o(@u)=9111-U/S1trz
T**
70
SAMPLE
***
FUNCTION
This instruction stores the value from each
specified input location.
PAR. DATA
NO. TYPE
DESCRIPTION
01: 2
Repetitions
02: 4
Starting input location
no.
Outputs
generated:
1
for each sample
11-2
01=Arctan (Ux/Uy)