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Measurement options
Document code: SS1-UM-1.05
Battery and memory management
When leaving the SunScan probe to Autolog over a few days, the memory space on
the Flashcard will determine how long it can run for, provided the Workabout Ni-Cd
battery is fully charged, and the probe alkaline batteries are not near the end of their
life. Approximate indications of data memory requirements are given in the earlier
Data memory management
section.
Warning! If you leave the Workabout in the field for Autologging, you must enclose
it in a bag or container with plenty of desiccant to protect it from the possibility of
internal condensation. If you are using the Beam Fraction sensor as well during the
Autolog process, bear in mind that the shade ring may need occasional
readjustment.
Measurement procedures in the field
Of course it is worth checking the equipment a day or two before your field
experiment for routine matters such as the state of the batteries and the internal
desiccant. See the Technical Reference section for details of these.
Probe handling in the field
Earlier sections in the SunScan User Manual (Measurement options and experiment
design) give you guidance as to what equipment you will need (BFS or not) and
what types of measurement you will make (LAI, PAR, or All). This section helps
with practical comments and advice.
The probe GO button
The red button on the probe handle allows you to initiate and store repetitive
readings from the probe without needing to look at the Workabout display. Listen for
the tones from the Workabout which tell you where you are in the process:
•
single beep - initiate
READ
•
double beep - accept
STORE
The
GO
button functions just like the
Enter
button on the Workabout, for all menu
options that are presented at the bottom of the screen.
Levelling the probe
The probe is fitted with a miniature bubble level to help you hold it level during the
measurements.
In most situations beneath the canopy, exact levelling of the probe is not critical.
Do your best to minimise your own shading of the probe when taking readings. If the
probe can "see" you, you will be blocking a certain amount of diffuse light from the
sky. Casting a dense shadow on the probe by blocking the direct beam could cause
significant errors.
Your best strategy will be to take as many samples as quickly as you can rather than
aim for perfection with each reading. This will counter the spatial variability of most
canopies, and is especially true if you have to work in unsteady light conditions.
When using the
GO
button, concentrate on getting the best levelling for the
READ
function (single beep) which then "freezes" the reading. It does not matter whether
the probe is level when you press
GO
the second time to store the reading.
