On the Local Isotropy of the Temperature Field in an Urban Area

Abstract Experimental results of simultaneous measurements of temperature differences in the streamwise, lateral and vertical directions during convective, new-neutral and stable conditions in the atmospheric boundary layer of an urban site are presented and discussed. The lateral and vertical temperature difference variances are found to be almost equal regardless of the conditions but only agree with the streamwise difference variance in convective or rear-neutral conditions. This points out the need for further investigation of the effects of stratification on the scalar fields. When local isotropy is satisfied, the difference spectra are shown to follow the theoretical behavior derived by Van Atta (1977).for temperature gradients in the inertial subrange.