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|Title:||Theoretical and Lidar Studies of the Density Response of the Mesospheric Sodium Layer to Gravity Wave Perturbations|
|Author(s):||Shelton, John Davis|
|Department / Program:||Electrical Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Engineering, Electronics and Electrical|
|Abstract:||Laser radar observations of the mesospheric sodium layer often reveal wavelike density fluctuations moving through the layer. It is often assumed that these features are a layer density response to gravity waves. The density response of atmospheric layers to gravity waves is developed in two forms; an exact solution and a perturbation series solution. The degree of nonlinearity in the layer density response is clearly described by the series solution whereas the exact solution gives insight into the nature of the response. It is shown that density perturbations in an atmospheric layer can be substantially greater than the atmospheric density perturbations associated with the propagation of a gravity wave. Because of the density gradients present in atmospheric layers, interesting effects are observed such as a phase reversal in the linear layer response which occurs near the layer peak. Once the layer response is understood, the sodium layer can be used as a tracer of atmospheric wave motions.
In order to increase the resolution of lidar data, a two-dimensional digital signal processing technique has been developed. Both spatial and temporal filtering are utilized to enhance the resolution by decreasing shot noise by more than 10 dB. Many of the features associated with a layer density response to gravity waves are observed in high resolution density profiles of the mesospheric sodium layer. These include nonlinearities as well as the phase reversal in the linear layer response.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
|Date Available in IDEALS:||2014-12-15|
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Dissertations and Theses - Electrical and Computer Engineering
Dissertations and Theses in Electrical and Computer Engineering
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois