Campbell Scientific IRGASON Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer - Manual (Page 60)

Appendix B. Equations
( ) 





+
−






+
=
v
v d
d X
X
T R
PM
1000
1
15 . 273
ρ (B-5)
Dew Point from Molar Mixing Ratio
tmp d
tmp d
d T
T
T
_
_
502 . 17
97 . 240
−
= (B-6 2 )
( ) 





+ ⋅
=
v
v
tmp d X f
P X
ln T
1000 61121 . 0 _
(B-7 2 )
( ) ( )
2 9 5 10 9 . 5 10 2 . 3 00072 . 1 PT P f − − Ч + Ч + =
(B-8 2 )
Water Vapor Molar Mixing Ratio from Dew Point
1000
e P
e
X
v −
= (B-9)






+
⋅ ⋅ =
d
d
T
T
EXP f e
97 . 240
502 . 17
61121 . 0 (B-10 2 )
Water Vapor Mass Density from Dew Point
( )( )
( ) 





+ +
=
d
d
v T
T
EXP
T R
f
97 . 240
502 . 17
15 . 273
61121 . 0 018 . 0
ρ (B-11 2 )
Vapor Pressure from Molar Mixing Ratio and Water Vapor Density
v
v
X
P X
e
+
=
1000
(B-12)
( )
v
v
M
T R
e
15 . 273 +
=
ρ
(B-13)
1 Leuning, R (2004) Measurements of Trace Gas Fluxes in the Atmosphere
Using Eddy Covariance: WPL Revisited. The Handbook of Micrometeorology,
29, 119-132. New York: Kluwer Academic Publishers. Eq. 6.23
2 Buck, A L (1981) New Equations for Computing Vapor Pressure and
Enhancement Factor. Journal of Applied Meteorology 20, 1527-1532. Eqs.
2a, 3a, and 6
B-2