A Comparison of Estimated and Measured Diurnal Soil Temperature Through a Clay Soil Depth

Abstract

In this study, diurnal soil temperature fluctuation through a clay soil depth was estimated with respect to time using a measured data set in a cosinusoidal harmonic equation. Some soil thermal properties, such as amplitude, heat diffusivity, damping depth and retardation time were also determined at 0, 10, 20, 30, 40 and 50 cm soil depth. The highest amplitude value 12.31°C was obtained at the soil surface. However, heat diffusivity, damping depth and retardation time increased at the deeper soil layers compared with the soil surface values. Estimated temperature values by the cosinusoidal harmonic equation fitted very well with the measured values. Estimated temperatures at 10 cm soil depth gave the significant correlations with measured data set by the Agricultural Faculty, Meteorological Station in Ondokuz Mayis University (0.903**) and measured temperatures at six times in a day by the researchers (0.861**). It showed validity of the equation under the given soil properties and boundary conditions. The most fluctuation in soil temperature with respect to time and depth was observed at the soil surface. Changes in soil temperature at the deeper layers (>30 cm) remained almost constant during a day.