Comparative Study on Methods for Computing Soil Heat Storage and Energy Balance in Arid and Semi-Arid Areas

Observations collected in the Badan Jaran desert hinterland and edge during 19-23 August 2009 and in the Jinta Oasis during 12-16 June 2005 are used to assess three methods for calculating the heat storage of the 5-20-cm soil layer. The methods evaluated include the harmonic method, the conduction-convection method, and the temperature integral method. Soil heat storage calculated using the harmonic method provides the closest match with measured values. The conduction-convection method underestimates nighttime soil heat storage. The temperature integral method best captures fluctuations in soil heat storage on sub-diurnal timescales, but overestimates the amplitude and peak values of the diurnal cycle. The relative performance of each method varies with the underlying land surface. The land surface energy balance is evaluated using observations of soil heat flux at 5-cm depth and estimates of ground heat flux adjusted to account for soil heat storage. The energy balance closure rate increases and energy balance is improved when the ground heat flux is adjusted to account for soil heat storage. The results achieved using the harmonic and temperature integral methods are superior to those achieved using the conduction-convection method.