Campbell CWB100, Инструкция по эксплуатации

Страница: 61 / 70

Appendix B. Measurement Names and Meanings
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)
where
Ux=(
Σ
sin
Θ
i
)/N
Uy=(
Σ
cos
Θ
i
)/N
or, in the case of orthogonal sensors
Ux=(
Σ
(Ue
i
/U
i
))/N
Uy=(
Σ
(Un
i
/U
i
))/N
where U
i
=(Ue
i
2
+Un
i
2
)
1/2
Standard deviation of wind direction,
σ
(
Θ
1) , using Yamartino algorithm:
σ
(
Θ
1)=arc sin(
ε
)[1+0.1547
ε 3
]
where,
ε
=[1-((Ux)
2
+(Uy)
2
)]
1/2
and Ux and Uy are as defined above.
Resultant mean horizontal wind speed,
U
:
U =(Ue
2
+Un
2
)
1/2
FIGURE B.3-2. Mean Wind Vector
where for polar sensors:
Ue=(
Σ
S
i
Sin
Θ
i
)/N
Un=(
Σ
S
i
Cos
Θ
i
)/N
or, in the case of orthogonal sensors:
Ue=(
Σ
Ue
i
)/N
Un=(
Σ
Un
i
)/N
Resultant mean wind direction,
Θ
u:
Θ
u=Arctan (Ue/Un)
B-5