A case study of short-term closure of the surface energy balance

A correct determination of the surface energy balance is an important quality test for measurements of turbulent surface fluxes. The energy balance is often not closed especially in non-homogeneous terrain and/or in presence of orographic obstacles. The daily energy budget is more easily closed but short-term closure is rarely obtained. In this work a data set from southern Italy is analyzed to discuss the main causes of the short and long term energy imbalance. Our analysis has shown that the global closure rate significantly improves after the correction for the error dependent on ultrasonic anemometer angle of attack and for the error dependent on the heat storage into the soil. Furthermore a significant reduction of short-term energy residual results by taking into account the contribution to the transport by ‘large scale motions’.