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Observations of the unambiguous 2‐dimensional horizontal wave number spectrum of OH intensity perturbations
Author(s) -
Gardner Chester S.,
Coble Mark,
Papen George C.,
Swenson Gary R.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl03158
Subject(s) - physics , wavenumber , azimuth , zenith , spectral density , intensity (physics) , zonal and meridional , spectrum (functional analysis) , distortion (music) , wavelength , spectral line , computational physics , optics , mathematics , amplifier , statistics , optoelectronics , cmos , atmospheric sciences , quantum mechanics , astronomy
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 technique involves computing the (ω, k, l ) = (ω, h, ϕ) spectrum of OH image collected over a several hour period, where k is the zonal wave number, l is the meridional wave number, h = ( k ² + l ²) 1/2 , ϕ = tan −1 ( k/l ), and ω is the temporal frequency. The data are used to study the azimuthal distribution of wave energy propagation and the separability of the ( h, ϕ) spectrum. The h spectral indices, computed from power‐law fits of the 2‐D spectrum over the wave number range 2π/(200 km) < h < 2π/(20 km), vary between −1.6 and −3.6 as a function of ϕ with a mean of −2.58. Consequently, the image spectrum is not separable in h and ϕ. We show that nonseparability is most likely associated with distortion of the wave perturbations caused by the viewing geometry at large zenith angles.