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Physical Sciences and Mathematics

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Embry-Riddle Aeronautical University

Publications

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1994

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Wave-Modified Mean Exothermic Heating In The Mesopause Region, Michael P. Hickey Ph.D., R. L. Walterscheid Nov 1994

Wave-Modified Mean Exothermic Heating In The Mesopause Region, Michael P. Hickey Ph.D., R. L. Walterscheid

Publications

We employ a model of wave-driven OH nightglow fluctuations to calculate the effects of gravity waves on the chemical exothermic heating due to reactions involving odd hydrogen and odd oxygen species in the mesopause region. Using a model based on time means and deviations from those means, it is demonstrated that gravity waves contribute to the time-average exothermic heating. The effect can be significant because the fractional fluctuations in minor species density can be substantially greater than the fractional fluctuation of the major gas density. Our calculations reveal that the waves mitigate the exothermic heating, demonstrating their potential importance in …

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Simulations Of The Effects Of Water Vapor, Cloud Liquid Water, And Ice On Amsu Moisture Channel Brightness Temperatures, Bradley M. Muller, Henry E. Fuelberg, Xuwu Xiang Oct 1994

Simulations Of The Effects Of Water Vapor, Cloud Liquid Water, And Ice On Amsu Moisture Channel Brightness Temperatures, Bradley M. Muller, Henry E. Fuelberg, Xuwu Xiang

Publications

Radiative transfer simulations are performed to determine how water vapor and nonprecipitating cloud liquid water and ice particles within typical midlatitude atmospheres affect brightness temperatures T-B's of moisture sounding channels used in the Advanced Microwave Sounding Unit (AMSU) and AMSU-like instruments. The purpose is to promote a general understanding of passive top-of-atmosphere T-B's for window frequencies at 23.8, 89.0, and 157.0 GHz, and water vapor frequencies at 176.31, 180.31, and 182.31 GHz by documenting specific examples. This is accomplished through detailed analyses of T-B's for idealized atmospheres, mostly representing temperate conditions over land. Cloud effects are considered in terms of …

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Automated Classification Of Stellar Spectra - I. Initial Results With Artificial Neural Networks, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin Jul 1994

Automated Classification Of Stellar Spectra - I. Initial Results With Artificial Neural Networks, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin

Publications

We have initiated a project to classify stellar spectra automatically from high-dispersion objective prism plates. The automated technique presented here is a simple back propagation neural network and is based on the visual classification work of Houk. The plate material (Houk’s) is currently being digitized, and contains « 105 stars down to K æ 11 at æ 2-Â resolution from « 3850 to 5150 Â. For this first paper in the series, we report on the results of 575 stars digitized from 6 plates. We find that even with the limited data set now in hand we can determine the …

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New Sources For The Hot Oxygen Geocorona, P. G. Richards, Michael P. Hickey Ph.D., D. G. Torr Apr 1994

New Sources For The Hot Oxygen Geocorona, P. G. Richards, Michael P. Hickey Ph.D., D. G. Torr

Publications

This paper investigates new sources of thermospheric non thermal (hot) oxygen due to exothermic reactions involving numerous minor (ion and neutral) and metastable species. Numerical calculations are performed for low latitude, daytime, winter conditions, with moderately high solar activity and low magnetic activity. Under these conditions we find that the quenching of metastable species are a significant source of hot oxygen, with kinetic energy production rates a factor of ten higher than those due to previously considered O2+ and NO+ dissociative recombination reactions. Some of the most significant new sources of hot oxygen are reactions involving quenching of O+(²D), O(¹D), …

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Comparison Of Theories For Gravity Wave Induced Fluctuations In Airglow Emissions, R. L. Walterscheid, G. Schubert, Michael P. Hickey Ph.D. Mar 1994

Comparison Of Theories For Gravity Wave Induced Fluctuations In Airglow Emissions, R. L. Walterscheid, G. Schubert, Michael P. Hickey Ph.D.

Publications

A comparison is undertaken of theories for the gravity wave induced fluctuations in the intensity of airglow emissions and the associated temperature of the source region. The comparison is made in terms of Krassovsky's ratio ηE for a vertically extended emission region (ηE is the ratio of the vertically integrated normalized intensity perturbation to the vertically integrated normalized intensity-weighted temperature perturbation). It is shown that the formulas for ηE in the works by Tarasick and Hines (1990) and Schubert et al. (1991) are in agreement for the case of an inviscid atmosphere. The calculation of ηE using the theory of …

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Automated Classification Of Stellar Spectra: Where Are We Now?, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin Jan 1994

Automated Classification Of Stellar Spectra: Where Are We Now?, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin

Publications

We briefly review the work of the past decade on automated classification of stellar spectra and discuss techniques which show par­ticular promise. Emphasis is placed on Artificial Neural Network and Principle Component Analysis based techniques, due both to our greater familiarity with these and to their rising popularity. As an example of the abilities of current techniques we report on our automated classification work based on the visual classifications of N. Houk (Michigan Spectral Catalogue, Vol. 1 - 4, 1975, 1978, 1982, 1988).

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