2026-09-21T04:23:59Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/69228 2023-07-11 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

Shelton, John Davis 2014-12-15T19:04:16Z 2014-12-15T19:04:16Z 10000-01-01 1982 1982 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. Made available in DSpace on 2014-12-15T19:04:16Z (GMT). No. of bitstreams: 1 8209629.pdf: 7437280 bytes, checksum: d2b1358ba967a43ae2f894f79f0a0e83 (MD5) Previous issue date: 1982 Embargo set by: Seth Robbins for item 69394 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 231 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982. http://hdl.handle.net/2142/69228 (UMI)AAI8209629 Engineering, Electronics and Electrical Theoretical and Lidar Studies of the Density Response of the Mesospheric Sodium Layer to Gravity Wave Perturbations text Electrical Engineering Electrical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.