229 Heat Dissipation Matric Water Potential Sensor
22
0
100
200
300
400
500
200
100
0
100
200
10 degrees C
16 degrees C
18 degrees C
22 degrees C
24 degrees C
30 degrees C
matric potential (-kPa)
error (-kPa)
Figure 6-3. Measurement error for range of soil temperatures and wetter range of matric potential.
A temperature correction for the difference in temperature at time of calibration
and time of measurement is provided in the work of Flint et al., 2002. To
implement the correction, normalized temperature must be used for the calibration
variable. Normalized temperature is as defined in equation [3].
The correction procedure is an iterative method. Examples of implementing the
iterative routine with dataloggers are given in programming examples 5 and 6.
The general sequence for using the temperature correction method is:
1.
Determine
dry
T
Δ
and
wet
T
Δ
prior to calibration and with sensor
conditions as described in 6.2.1. The recommended
T
Δ
is the sensor
temperature after 30 seconds of heating minus the sensor temperature
after 1 second of heating.
2.
With the sensor in place, use the
T
Δ
from the in situ measurement along
with the
dry
T
Δ
,
wet
T
Δ
values for the particular sensor to calculate
norm
T
Δ
.
