Soil heat flux determination: a null-alignment method
1975
Kimball, B.A. | Jackson, R.D.
A new technique for computing soil heat flux was developed which is based on measurements of only temperature and moisture content of the upper 20 cm of soil. First, calorimetry is used to calculate an initial estimate of the soil heat flux from an initial estimate for the thermal conductivity at 20 cm. Then the temperature profiles for those times when zero temperature gradients exist somewhere in the upper 20 cm are used to force a “null alignment” of zero soil heat flux with zero temperature gradient by correcting the thermal conductivity at 20 cm. Next, the corrected thermal conductivity at 20 cm is used to recalculate the soil heat flux for all time periods during the day. To test the null-alignment technique, moisture content, temperature, and heat flux from heat flux plates were measured at half-hour or less intervals for a bare soil over a two-week period following irrigation. Soil heat fluxes computed with the null-alignment technique were comparable to those measured with the heat flux plates.
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