Abstract: In this paper, the characteristics of the energy transmission near the surface layer over desert substantial underlying surface in arid area were analyzed, the study was carried out with the observation instruments, and the influence of these instruments on the surface energy balance was researched based on the observed data obtained from the Inner Mongolia Micro meteorological Observation Experiment (IM-MmOE). In designing the experiment, the observed inconsistent impact on energy closure was maximized as much as possible. The ideal underlying surface for the observation should be homogeneous, but the actual one was inhomogeneous, so the observation precision of surface energy flux was not reached an ideal level, and the influence of observation errors on the surface energy closure was widely concerned. The results showed that the surface energy transfer in the desert underlying surface in arid area was mainly dominated by sensible heat flux and surface soli heat flux. The observed correlation coefficients of the most radiation instruments were higher than 0.98, the correlation coefficients of observed surface soil heat flux and sensible heat flux were higher than 0.97, and the correlation coefficient of observed latent heat flux was the lowest and only 0.92. The mean squared errors of surface soil heat flux, latent heat flux and sensible heat flux were 14.3 W·m^-2, 8.9 W·m^-2 and 8.0 W·m^-2 respectively, the observed data of all the instrument were consistent well, and the observation errors were low. Deviations of the observed data caused by the nonuniformity could affect directly the rate of energy closure, the observed deviations of turbulent flux (the sum of sensible heat flux and latent heat flux) caused an uncertainty of 1%-3% of the surface energy closure rate, the effective energy (the difference between net radiation and surface soil heat flux, the deviation of observed surface soil heat flux was considered only) brought about an uncertainty of 5%, and the total deviation of the data of turbulent flux and effective energy resulted in an uncertainty of 6%-8% of surface energy.

Key words: energy closure, energy flux, surface radiation, observation error, arid area