Vaisala AWS330, User Manual, Page: 291 / 298

Appendix B ______________________________________________________ Calculation Formulas
VAISALA ______________________________________________________________________ 287
Wind Speed (U
2
)
Estimate wind speed at 2 m height when measured at height z.








) 42 . 5 ) 8 . 67 ln((
87 , 4
2
z
U U
z
where
Uz = Wind speed measured at height z [ms
-1
]
z = Height of wind speed measurement [m]
Vapor Pressure Deficit (e
a
-e
d
)














  
d
a a
d a
e
T e T e
e e VPD
2
) ( ) (
) (
min max
where
e
a
= Saturation vapor pressure [kPa]
e
d
= Actual vapor pressure [kPa]








3 . 237
27 . 17
exp 611 . 0 ) (
max
max
max
T
T
T e
a








3 . 237
27 . 17
exp 611 . 0 ) (
min
min
min
T
T
T e
a














100
) (
2
1
100
) (
2
1
min
max
max
min
RH
T e
RH
T e e
a a d
where
T
max
=
Maximum daily temperature [

C]
T
min
=
Minimum daily temperature [

C]
e
a
(T
max
) = Saturation vapor pressure at T
max
e
a
(T
min
) = Saturation vapor pressure at T
min
e
d
(T
max
) = Actual vapor pressure at T
max
e
d
(T
min
) = Actual vapor pressure at T
min
RH
max
= Maximum daily relative humidity [%]
RH
min
= Minimum daily relative humidity [%]