The unambiguous 2-D horizontal wave number spectrum of gravity wave perturbations in OH emission intensities is computed from imager observations acquired on 2 Feb 1995 at the Starfire Optical Range, NM. The tech-nique involves computing the (w, k, l) = (w, h, f) spectrum of OH images collected over a several hour period, where k is the zonal wave number, l is the meridional wave number, h = (k² + l²)^1/2, f = tan^-1(k/l), and w is the temporal frequency. The data are used to study the azimuthal distribution of wave energy propagation and the separability of the (h, f) spectrum. The h spectral indices, computed from power-law fits of the 2-D spectrum over the wave number range 2p/(200 km) < h < 2p/(20 km), vary between -1.6 and -3.6 as a function of f with a mean of -2.58. Consequently, the image spectrum is not separable in h and f. We show that nonseparability is most likely associated with distortion of the wave perturbations caused by the viewing geometry at large zenith angles.

Citation: Gardner, C. S., M. Coble, G. C. Papen, and G. R. Swenson (1996), Observations of the Unambiguous 2-Dimensional Horizontal Wave Number Spectrum of OH Intensity Perturbations, Geophys. Res. Lett., 23(25), 3739–3742.