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Belyaev A.N.,Institute of Applied Geophysics
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2013

The aim of this work is to develop mathematical foundation of a method which can be used to infer the three-dimensional gravity wave characteristics from multi position airglow observations from space. This work derives a one-dimensional Fredholm integral equation of the first kind, which describes the relations between the gravity wave spectrum and spatial structure of wave perturbations registered by a space-based airglow imager. It is shown that the solution of this equation belongs to the central slice through a three-dimensional gravity wave spectrum, whose plane is perpendicular to the optical axis of the airglow imager. Thus, in order to retrieve the three-dimensional gravity wave characteristics from the airglow observations performed from space, it is needed to obtain the set of images of a local emission layer area from different imager positions. Then this data must be processed using the developed mathematical techniques to obtain a set of the central slices of the three-dimensional gravity wave spectrum. Applying the technique, for a superposition of three individual waves, amplitude and wave vector can be determined. © 2013 Elsevier Ltd. Source


Belyaev A.,Institute of Applied Geophysics
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2016

Model-based investigations of the wave-induced responses of O(1S), O2(b,0-0) and OH(8-3) emissions have been performed. A series of digital experiments performed using the one-dimensional simulation model proposed by Liu and Swenson (2003) demonstrated that, in addition to the variable component, the wave disturbance of airglow emissions has a constant component. This component is the enhancement/depletion of the background emission intensity of an emission layer. To interpret its appearance, the simplest analytical model of airglow disturbance due to a gravity wave has been constructed. This model indicates that enhancement/depletion of the background emission intensity is a nonlinear airglow response to a wave disturbance. Its magnitude depends quadratically on the wave amplitude and can reach a few dozen percent relative to the value of the zenith brightness of the unperturbed OH(8-3)/O(1S) emission layer. © 2016 Elsevier Ltd Source


Danilov A.D.,Institute of Applied Geophysics
Advances in Space Research | Year: 2013

The F2-region reaction to geomagnetic storms usually called as an ionospheric storm is a rather complicated event. It consists of so called positive and negative phases, which have very complicated spatial and temporal behavior. The main morphological features of ionospheric storms and the main processes governing their behavior were understood at the end of the 1900s and described in a series of review papers. During the recent decade there were many publications dedicated to the problem of ionospheric storms. In this paper a concept of ionospheric storm morphology and physics formulated at the end of the 1990s is briefly summarized and the most interesting results obtained in the 2000s are described. It is shown that the main features of the studies of the previous decade were: the use of GPS TEC data for analyzing the ionospheric storm morphology, attraction of sophisticated theoretical models for studying the processes governing ionospheric behavior in disturbed conditions, and accent to analysis of ionospheric behavior during prominent events (very strong and great geomagnetic storms). Also a special attention was paid to the pre-storm enhancements in foF2 and TEC. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved. Source


Danilov A.D.,Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2012

The current views on long-term changes in parameters (trends) in the upper atmosphere and ionosphere are considered. The concept of cooling and contraction of the middle and upper atmosphere due to the increase in the amount of greenhouse gases in the atmosphere is described. © 2012 Pleiades Publishing, Ltd. Source


Danilov A.D.,Institute of Applied Geophysics
Geomagnetism and Aeronomy | Year: 2011

Changes in the values of the critical frequency of the F2 layer from 1990 to 2005-2007, according to median data, are considered. Eleven stations, for which the necessary data are available, have been found in international databanks. The conclusion of the previous publication by Danilov (2011) that at the end of the 1990s and beginning of the 2000s a negative trend in foF2 was observed both after sunset and in the daytime is confirmed. © 2011 Pleiades Publishing, Ltd. Source

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