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ehs.10cm: -0.5%
ehs.20cm: -2.5%
5/29/15:
I've also tried to remove the diurnal cycle, assuming that it is a temperature affect (since vegetation shouldn't have been very active, especially at the beginning of this experiment). I use the correction:
Q_correct(z) = Q_meas(z) - xm*Tsoil(z),
where:
xm = c(0.11,0.18,0.17,0.12,0.20,0.18) for bao 5,10,20 and ehs 5,10,20 cm, respectively.
With this temperature correction, the bias correction changes a bit:
Q_correct(z) = Q_meas(z) + xb - xm*Tsoil(z)
xb = c(2.3,2.7,5.0,0.5,-0.5,-2.5) (same order as xm, above)
After these corrections, I get the attached plot: Qgrav.pdf, where the left panels are from bao, the right panels from ehs, the top panels are just a bias correction and the bottom panels are with the combined correction. Also on these plots are the gravimetric samples as circles. For ehs, Qsoil was read manually (independent of the data system) at the time of the second soil cores, and these values are plotted as "+" (though I don't have the corresponding Tsoil to apply the combined correction).