Owner manual

User's Guide ______________________________________________________________________
286 _________________________________________________________________ M211296EN-B
Soil Heat Flux (G)






Δ
−
=
−
t
TT
dcG
nn
ss
1
where
T
n
=
Temperature on day n [°C]
T
n-1
=
Temperature on preceding day n-1 [°C]
Δt
= Time period [days]
c
s
=
Volumetric heat capacity [MJ m
-3
°C
-1
] (2.1 for average
moist soil is used)
d
s
= Estimated effective soil depth [m] (0.2 m is used)
Psychometric Constant (γ)
λελ
γ
P
PC
p
00163.010
3
=⋅=
−
where
γ
=
Psychometric constant [kPa °C
-1
]
C
p
=
Specific heat of moist air = 1.013 kJ kg
-1
°C
-1
P = Atmospheric pressure [kPa]
ε
= Ratio molecular weight water vapor/dry air = 0.622
λ
= Latent heat of vaporization [ML kg
-1
]
λ is given by the following formula:
T)10361.2(501.2
3−
⋅−= λ
Average Air Temperature (T)
Where hourly data is available:

=
=
24
0
24
i
i
T
T