PP Systems TARGAS-1, Инструкции по эксплуатации

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TARGAS-1 Operation Manual V. 1.02 76 support@ppsystems.com
r
b
= boundary layer resistance to water vapor transfer, empirically determined for each cuvette by
the pseudo-leaf (filter paper) method. 0.93 converts it to that for heat transfer.
σ
= Stefan Boltzmann constant
T
c
= cuvette air temperature
H
is calculated from the photon flux incident on the cuvette (
Q
), taking into account the ratio of infra-red to
visible radiation and typical reflection/absorption factors by the leaf:
H = Q × Trans
Where
Trans
= 0.14 the ratio of infrared to visible radiation, and converting photon flux to energy units
To simply computation, the following approximation is made:
4σ × ((T
c
+ 273)
3
)
≅ � 4.639 + (0.5834 × T
c
)
�
(A.7) Then, the leaf temperature is:
T
leaf
= (T
c
+ ∆ t)
Saturation Vapor Pressure
Derive saturation vapor pressure at leaf temperature (
e
leaf
) from
T
leaf
(A.8) From Buck, 1981 (using e
w1
and f
w1
) we calculate :
e
leaf
= 6.1365 × exp �
T
leaf
× (17.502)
T
leaf
+ 240.97
�
Where
e
leaf
= saturated water vapor pressure inside leaf at
T
leaf
Stomatal Conductance
Calculate stomatal conductance (g
s
)
(A.9) From von Caemmerer & Farquhar, 1981 (Eq B14), total leaf conductance to H
2
O transfer is
calculated as:
g
total
=
E × (P‐(e
leaf
+ e
out
)/2)
(e
leaf
‐e
out
)
(A.10) Since
1/
g
total
= r
s
+ r
b
,
(A.11) stomatal resistance can be calculated as:
r
s
(m
2
s mol
‐ 1
) = �
(e
leaf
‐e
out
)
(E × (P‐(e
leaf
+ e
out
)/2))
� ‐r
b
(A.12) Stomatal conductance is the inverse of stomatal resistance: