Predicting bare soil temperature. III. Extension to single‐day variation

Summary The theory developed earlier to describe the averaged diurnal wave of bare soil temperature for a many‐day interval is extended to single‐day variation. This gives a new analytic model for the soil thermal ‘weather’(as opposed to ‘climate’) under typical temperate seedbed conditions, with input meteorological data in standard time‐series form. The model incorporates (i) a ‘ramp’ term to account for overall linear ascent or descent (i.e. non‐cyclic change) in the surface temperature, TO ; and (ii) the actual initial condition, θ(z), of the temperature profile, which expresses its effect through a transient term. Soil temperature T (z, t) thus has three distinct components‐periodic, ramp, and transient. The model is tested against data from a field site for I day each in spring and autumn.