Delta Electronics SS1-UM-1.05 User Manual

Page 23

SunScan User Manual v 1.05

SunScan Tutorial

••••

By now you may have accumulated quite a lot of readings in

Data.PRN

the default

data file. There is no harm in this, but you may want to put further test results into
new file, or maybe try out a

.CSV

file. If so, follow the Data Storage instructions a

few pages back.

Measuring Leaf Area Index without a Beam Fraction Sensor

This is the most complicated of the combinations of probe and display settings. The
Measurement Options sections discusses in detail the conditions for which it is
possible and desirable to make this measurement.

♦

set the

Ext sensor:

none

The

Next Reading

screen now includes

extra options for reading

INCIDENT

and

B FRAC

- and it won’t let you proceed

with a

READ

until you’ve taken these

readings.

♦

Highlight

B FRAC

and press

Enter

Hold the probe level above the canopy as
before, but now cast a small shadow over
part of the probe. Don't hold the shade too
close to the probe - otherwise it will cut
out some of the diffuse light as well.

SunData looks at the readings from the
photodiodes and uses the lowest value to
calculate the

Diffuse

component of the

incident light. It uses the highest
photodiode values to calculate the

Total

incident, and uses these two values to
calculate and display the

Beam Fraction

Note: SunData uses this value for the Beam Fraction to increase the accuracy of
the calculation of Leaf Area Index, as explained in the LAI Theory section.
However, this is a secondary effect, and you should not worry unduly about the
second decimal place for the Beam Fraction value.

♦

Press

Enter

or the red button to

STORE

the Beam Fraction reading.

You can now continue to take readings with the probe and display the LAI as before
- that is, until the light conditions change, when you will need to retake the Beam
Fraction readings. If you wish to recheck only the incident light reading, you can do
so as follows:

♦

Hold the probe level above the canopy, and make sure as little as possible of your

own outline is being seen by the probe.

♦

Use the

←

→

arrow keys to highlight

INCIDENT

, and press

Enter

SunData will display the reading from
the probe:

♦

Press

Enter

or the red button to store

this as the Incident PAR reading.