6-8
Using the 10 and 20 cm Survey Chambers
Use the Chamber pull-down menu to choose 10 cm Survey (8100-102) or 20
cm Survey (8100-103). The appropriate Chamber Volume value is
automatically entered.
The Temperature Source determines where the air temperature measurement
used for the flux calculations is obtained. When using a LI-COR soil chamber,
this field should always be set to ‘Chamber’, so that the temperature
measurement is made using the thermistor located inside the chamber. For
other experimental protocols (e.g. making flask measurements), however, you
can choose to map the temperature measurement to any of the analog voltage
input channels (V1-V4 with the Auxiliary Sensor Interface, or V2-V4 with the
8100-104/C and the LI-8150 Multiplexer), and then use the appropriate V1-V4
tabbed page to enter the coefficients for the user-supplied temperature
thermistor. The temperature derived from that input channel will then be used
for the calculations.
Enter the Soil Area (83.7 cm
2
for 8100-102, and 317.8 cm
2
for 8100-103)
and Chamber Offset (cm). The Chamber Offset is the distance (in cm)
between the soil surface and the top of the soil collar, and is dependent upon
the depth that the collar is inserted into the ground. The soil CO
2
flux
measurement requires an accurate estimate of the Total System Volume. The
LI-8100A software uses the Chamber Offset and the Soil Area values to
calculate the volume of air inside of the soil collar. This value is, in turn,
added to the Chamber Volume to obtain the Total Volume. Measuring the
Chamber Offset is described in Section 2, Using Soil Collars.
Click on Apply to Port to send these values to the LI-8100A for
implementation.
3. Click on the Observation tab to open the Observation window.
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