Abstract: This paper studied the diurnal and seasonal characteristics of sensible and latent heat fluxes over a temperate desert steppe ecosystem in Inner Mongolia, based on the 2008 observation data from eddy covariance tower. The diurnal patterns of sensible and latent heat fluxes over the ecosystem were both single kurtosis, with the maximum value being  319.01 W·m^-2 (on May 30th, 2008) and 425.37 W·m^-2 (on Jun 2nd, 2008), respectively, and occurred at about 12:00-13:30 (local time), which was similar to the diurnal pattern of net radiation but lagged about one hour of the maximum net radiation. The maximum diurnal variations of monthly mean sensible and latent heat fluxes occurred in May and June, and their minimum diurnal variations occurred in January and November, respectively. There was a closer relationship between soil moisture content and precipitation. Surface soil moisture content was most sensitive to precipitation, while the moisture content in deeper soil layers had a lagged response to precipitation. The seasonal dynamics of sensible and latent heat fluxes was similar to that of net radiation, and affected by precipitation. Sensible heat flux was obviously affected by net radiation, but latent heat flux was more sensitive to precipitation and mainly controlled by soil moisture content.

Key words: desert steppe, sensible heat flux, latent heat flux, soil moisture content, sugarcane-soybean intercropping, cultivar, low nitrogen, yield, quality, economic benefit.