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Record Details

Record 60 of 24958
Line Coupling in Atmospheric Spectra
Offline Availability: Go to Request Form
Author and Affiliation:
Tipping, R. H.(Alabama Univ., Dept. of Physics and Astronomy, Tuscaloosa, AL United States)
Abstract: The theoretical modeling of atmospheric spectra is important for a number of different applications: for instance, in the determination of minor atmospheric constituents such as ozone, carbon dioxide, CFC's etc.; in monitoring the temperature profile for climate studies; and in measuring the incoming and outgoing radiation to input into global climate models. In order to accomplish the above mentioned goal, one needs to know the spectral parameters characterizing the individual spectral lines (frequency, width, strength, and shape) as well as the physical parameters of the atmosphere (temperature, abundances, and pressure). When all these parameters are known, it is usually assumed that the resultant spectra and concomitant absorption coefficient can then be calculated by a superposition of individual profiles of appropriate frequency, strength and shape. However, this is not true if the lines are 'coupled'. Line coupling is a subtle effect that takes place when lines of a particular molecule overlap in frequency. In this case when the initial states and the final states of two transitions are connected by collisions, there is a quantum interference resulting in perturbed shapes. In general, this results in the narrowing of Q-branches (those in which the rotational quantum number does not change), and vibration-rotational R- and P branches (those in which the rotational quantum number changes by +/- 1), and in the spectral region beyond band heads (regions where the spectral lines pile up due to centrifugal distortion). Because these features and spectral regions are often those of interest in the determination of the abundances and pressure-temperature profiles, one must take this effect into account in atmospheric models.
Publication Date: Oct 01, 1996
Document ID:
19970010178
(Acquired Mar 13, 1997)
Accession Number: 97N15395
Subject Category: GEOPHYSICS
Coverage: Final Report
Document Type: Technical Report
Publication Information: (SEE 19970010146)
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA United States
Organization Source: Alabama Univ.; Dept. of Physics and Astronomy; Tuscaloosa, AL United States
Description: 3p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: ATMOSPHERIC MODELS; SPECTRUM ANALYSIS; SPECTRAL BANDS; ATMOSPHERIC COMPOSITION; CLIMATE MODELS; ATMOSPHERIC TEMPERATURE; CARBON DIOXIDE; CENTRIFUGAL FORCE; TRACE ELEMENTS; MATHEMATICAL MODELS
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