TURBULENT CHARACTERISTICS AND BULK TRANSFER-COEFFICIENTS OVER THE DESERT IN THE HEIFE AREA

Observations of surface-layer turbulence and turbulent fluxes were mad e over a desert in northwestern China as a part of HEIFE (HEIhe river Field Experiment). These show that the normalized variations of the ve rtical wind component and of the air temperature obey Monin-Obukhov si milarity well, especially in free convective conditions. However, the variations of specific humidity do not obey Monin-Obukhov similarity. Mean bulk transfer coefficients of sensible heat and momentum flux are obtained as functions of stability over a wide stability range from t he observed data of turbulent fluxes and mast profiles. However, the b ulk transfer coefficient for water vapor could not be obtained because of the large scatter of the data. in free convective conditions, the sensible heat flux was found to be approximately proportional to the 1 .4 power of temperature difference between the surface and 20m. The bu lk transfer coefficient of sensible heat is also obtained as a functio n of the bulk Richardson number for practical convenience.