Experimental Test to Compare Viability of Various Theories of Atmospheric Velocity Fluctuations.

摘要

Several theories of velocity fluctuations in the atmosphere are discussed in the context of the horizontal wavenumber power spectral density (PSD). The main purpose of this report is to provide an experimental method to decide the question of which of these various theories are viable. The presently existing explanations of this PSD fall into the following categories: (a) quasi- two-dimensional turbulence theories as proposed by Gage and by Lilly; (b) theories of waves in cascade as proposed by Dewan; (c) 'separable' gravity wave theories which explain horizontal wavenumber PSD slopes in terms of vertical wavenumber and temporal frequency PSD slopes, as proposed by Gardner et al., and (d) the diffusive filtering theory, as proposed by Gardner. The experimental test proposed in this report is based on the horizontal wavenumber PSD observations of Nastrom and of Bacmeister et al, who reported that, under certain circumstances, this PSD exhibited a change of slope (going from -5/3 to -3) as the wavenumber increased.