SENSIBLE HEAT-FLUX FROM ARID REGIONS - A SIMPLE FLUX-VARIANCE METHOD

Similarity models in the inner region of the unstable atmospheric boun dary layer (ABL) are generally based on four dimensional parameters: b uoyancy, friction velocity, surface heat flux, and the height above th e land surface. In the free convection limit the friction velocity can be neglected, thus reducing the measurement needs in practical applic ations. Some field measurements of the second moment of temperature ha ve indicated that free convection scaling of this statistic may be ext ended into more dynamic regimes, namely, the ''dynamic-convective'' an d, perhaps, the ''dynamic'' regions of the ABL. An advantage of this a pproach is that the sensible heat flux can be estimated without shear stress measurements. This temperature variance similarity model is app lied for a wide range of unstably stratified flows over the dry Owens Lake, in southeastern California. The simple free convection model of the temperature variance is accurate for sensible heat flux estimation across the full range of unstable atmospheric stability conditions.