Application of tomographic inversion in studying airglow in the mesopause region

Abstract

Abstract. It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with di erent elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the ®rst inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to ®nd out the limitations of the method.

Experimental Validation of a Technique to Estimate Vertical Wavelength Parameters From Gravity Wave Perturbations on Mesospheric Airglows

“…Tomographic methods have been developed that use multiple observations of a single airglow layer from different locations on the ground [26]- [28] and from an aircraft [29]. These methods require the solution to an inverse problem to reconstruct the perturbation.…”

Radar observations of simultaneous traveling ionospheric disturbances and atmospheric gravity waves

“…Indirect manifestations of AGWs at ionospheric altitudes can be present in airglow and total electron content. In airglow images, AGWs can be visible as clear wavefronts [Taylor et al, 1995;Nygrén et al, 1998;Nakamura et al, 1999;Gardner et al, 1999;Kubota et al, 2001Kubota et al, , 2011Pallamraju et al, 2014]. TID observations are made by various radar and tomographic methods.…”

Tomographic imaging of airglow from airborne spectroscopic measurements

“…Despite the amount of research pertaining to atmospheric tomography, the works that deal with nonauroral mesospheric emission tomography remain relatively scarce. In [23,24], stochastic regularization principles were applied to a tomographic model and later to real data from two cameras. The result was a two-dimensional reconstruction from which the authors make the case that more imagers are needed to produce more accurate reconstructions.…”