Surface Energy-Balance Closure in a Gully Region of the Loess Plateau at SACOL on Eastern Edge of Tibetan Plateau

Surface energy-balance closure in a typical gully region of the Loess Plateau on the eastern edge of Qinghai-Xizang Plateau were studied based on the turbulence and radiation data observed at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) in a period of 6 consecutive sunny days for each month from June to August 2008. The results show that the sensible heat flux considering the vertical advection item of energy transport to the energy budget equation (H-ec + H-mv) in the gully region on summer sunny days accounted for 39.4% of net radiation, and the surface soil heat flux considering the heat storage term from the surface to the flux-plate (G + Delta G) for 29.6%, and the latent heat flux (LE) account for 26.5%, after all corrections. The closure rate of surface energy for the typical environment of the Loess Plateau reached 93.2% and was higher during the day than at night. Consideration of soil heat storage (Delta G) and the vertical advection effect (H-mv) significantly improved the surface energy closure rate. It is seen that in the typical semi-arid Loess Plateau region, even in the rainy season, sensible heat is still dominant over various components of surface energy expenditure.