PP Systems TARGAS-1 - Definition of Symbols and Physical Constants Used in Equations

TARGAS-1 Operation Manual V. 1.02 89 support@ppsystems.com
• the leaf is exposed on both upper and lower leaf surfaces
• the upper and lower boundary layer resistances are similar
• stomata are evenly distributed on both upper and lower leaf surfaces.
Definition of Symbols and Physical Constants Used in Equations
Measured Parameters
Symbol
Parameter
Unit
V

Flow rate of dry air into cuvette at STP
cc min
-1
a
Projected leaf area
cm
2
r

Boundary layer resistance to water vapor
m
2
s mol
-1
P
Atmospheric pressure
mb
Q
Photon flux density incident on cuvette
µmol m
-2
s
-1
T

Cuvette air temperature
°C
Calculated Parameters
Symbol
Parameter
Unit
W
Mass flow of air per unit leaf area into cuvette
mol m
-2
s
-1
e

Partial pressure of water vapor of air entering cuvette = H
2
Or
mb *
e

Partial pressure of water vapor of stirred cuvette air = H
2
Oa
mb *
E
Transpiration rate
mmol m
-2
s
-1
e

Saturated vapor pressure (inside the leaf) at leaf temperature
mb
T

Leaf temperature
°C
t
Temperature difference between the air and the leaf
°C
H
Radiation absorbed by the leaf
W m
-2
r

Stomatal resistance to water vapor
m
2
s mol
-1
g

Stomatal conductance to water vapor
mmol m
-2
s
-1
C

CO
2
concentration of air entering cuvette = CO
2
r
µmol mol
-1
*
C

CO
2
concentration of air inside and exiting the cuvette = CO
2
a
µmol mol
-1
*
A
CO
2
Assimilation rate (net photosynthesis)
µmol m
-2
s
-1
g

Total conductance to CO
2
transfer
mmol m
-2
s
-1
g

Total conductance to H
2
O transfer
mmol m
-2
s
-1
C

CO
2
concentration of sub-stomatal cavity
µmol mol
-1