CIRAS-3 Operation Manual V. 1.09
77
Settings (Continued)
Temperature
Sensor
Control Type
(
Available options are
dependent on PLC3
type)
Leaf Temperature
. There are several options by which to control the
temperature in the leaf chamber, temperature can be held fixed or allowed to
vary with ambient depending on experimental objectives. Leaf
temperatures
allow fixed inputs in 1 °C increments. Select
Leaf temperature
to hold the leaf
at a fixed temperature that you enter under “Set Temperature” (see below).
Track leaf to ambient
allows the leaf temperature to follow ambient
temperature, as measured by the cuvette’s handle-mounted thermistor sensor.
Cuvette temperature
is used to control the air in the cuvette at a fixed
temperature that you enter under “Set Temperature” (see below).
Track cuvette to ambient
allows the cuvette temperature to follow air
temperature, as measured by the cuvette’s handle-mounted sensor.
Disable temperature control
is intended mainly for diagnostic purposes but
can also be used for field measurements if required. This option is not
recommended for conditions that include high ambient temperature and/or high
light intensities as it will cause the cuvette to heat up.
Set Temperature
(
Available options are
dependent on PLC3
type)
Available if Temperature Sensor Control Type is set to control
Leaf
Temperature
or
Cuvette Temperature
. Enter a temperature value that is
between ~10 °C below ambient to 15 °C above ambient. The absolute control
range is between 0-45 °C. Ability to control at a stable temperature will depend
on whether you are operating the system from AC power or battery, the charge
state of the internal battery(s) and the following:
1. Leaf transpiration in the cuvette
2. Light (incident radiation)
3. Size and construction of the PLC window
Leaf Area
The default value will be based on your
Accessory
selection in the Settings
dialog. Enter known measured leaf areas if your leaf sample completely fills the
PLC3 Universal cuvette window or if you and you have pre-determined the leaf
area exposed in the chamber. Enter a lower estimate (as compared to the
window size) if you don’t know the true leaf area of your sample. All
calculations are based on leaf area so if you don’t know the actual leaf area at
time of measurement, you will need to perform leaf area analysis at the
conclusion of measurements and have the data recalculated. PP Systems can
supply a simple CIRAS-3 Excel
®
spreadsheet program for recalculation of
results.
Boundary Layer
Resistance
This value is determined at the factory prior to shipment and the value noted on
the PLC3 “Tested” label on your leaf cuvette. In future this will also be available
in software. Users should measure the boundary layer when changing out the
PLC3 Universal window as this value will vary from window to window. See
Boundary Layer Determination (rb)
on page 197.
