Vaisala AWS330 - Page 291

Appendix B ______________________________________________________ Calculation Formulas
VAISALA______________________________________________________________________ 287
Wind Speed (U
2
)
Estimate wind speed at 2 m height when measured at height z.








)42.5)8.67ln((
87,4
2
z
UU
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
aa
da
e
TeTe
eeVPD
2
)()(
)(
minmax
where
e
a
= Saturation vapor pressure [kPa]
e
d
= Actual vapor pressure [kPa]










3.237
27.17
exp611.0)(
max
max
max
T
T
Te
a










3.237
27.17
exp611.0)(
min
min
min
T
T
Te
a














100
)(
2
1
100
)(
2
1
min
max
max
min
RH
Te
RH
Tee
aad
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 [%]