A HEURISTIC MODEL OF 3-DIMENSIONAL SPECTRA OF TEMPERATURE INHOMOGENEITIES IN THE STABLY STRATIFIED ATMOSPHERE

Many measurements have shown that the random temperature fields in the stably stratified atmosphere are not locally isotropic (LI). The loca l axial symmetry (LAS) hypothesis looks more appropriate under these c onditions. The object of this paper consists in the development of a f lexible tool for spectral studies of LAS scalar fields independently o f their origin in stably stratified geophysical flows. A heuristic mod el of a 3D spatial spectrum is proposed in order to describe and study statistical properties of LAS temperature inhomogeneities from LI str uctures up to quasi-layered ones. To simplify the solution of this pro blem, a main assumption was accepted: the consideration is restricted to 3D spectra which may be given on a one-parametric family of surface s of rotation. Such 3D spectra may be represented by a single function of one variable which is the parameter of the family. This approach a llows one to introduce the generalized energy spectrum which describes an energy distribution according to inhomogeneity sizes. The family o f surfaces determines the shape of inhomogeneities. The family of elli psoids of rotation and power-law generalized energy spectrum is used a s the simplest example of the model application in order to study the general properties of LAS-structure spectra. The behavior of vertical, horizontal, and oblique 1D spectra and coherency spectra is studied. The relationship between the suggested model and some existing models of temperature spectra is considered. The application of the model for the analysis of experimental data is shown for two sets of measuremen ts. It is shown that the suggested model may quantitatively describe e xperimental 1D spectra and coherency spectra from a unique point of vi ew. It is noted that the model may be used for both the planning of me asurements and data processing. Possible generalizations of the model are considered for random fields with more degenerate symmetry and for space-temporal spectra.