LI-COR LI-6400, Manual

Page: 415 / 846

Defining User Variables
Examples
Using the LI-6400 15-13
Remarks on page 9-12). Otherwise, they can be treated just like user vari-
ables (they are user variables) in that you can log them, display them, plot
them, etc.
Examples
Water Use Efficiency
Suppose we want to add some measure of water use efficiency to the compu-
tations being performed by OPEN, as given by the ratio of photosynthetic rate
A (µmol m
-2
s
-1
) to transpiration E (mol m
-2
s
-1
). Thus, our water use efficien-
cy W (%)will be
. (15-1)
■ ■
■ ■
To add water use efficiency to the current ComputeList:
1 Access
"Edit the Current ComputeList"
Starting from OPENÕs main screen, press Config Menu ( F2 ), then select
"_ComputeList Menu"
2 Decide where to insert the new variable.
Since weÕll need both photosynthetic rate and transpiration for this equation,
scroll down below where they are defined (see Figure 15-10).
W
A 10
6 Ð
´
E
---------------------- 100
´
=
" StdCond(#20, Tleaf_c, condBL_mol, pres
##30 "Photo" "Photosynthesis (umol/m2/s)
" -#10 * co2_diff_um - co2_2_um * #20"
_
##35 "CndCO2" "Total Conductance to CO2"
" 1.0 / (1.6 / #23 + 1.37 / condBL_mol)"
Figure 15-9. Implementing Equation 15-1 in a Compute List.
Put cursor here
400
/User/Config s /Comps/Default