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  • Author or Editor: R. G. Roper x
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Prakash M. Dolas
and
R. G. Roper

Abstract

The wind data generated by an all sky, continuous wave radio meteor wind facility at Atlanta (34°N, 84°W) is analyzed over the period of August 1974 through July 1975. Zonal and meridional components of the prevailing wind over the height range of 80–100 km, at 2 km intervals represent 5–10 day averages where the tidal components have been removed. Large southerly wind during winter and weak northerly wind during summer at 80–100,km altitude is consistent with other observations and mesospheric circulation models.

Various phases of the 1974–75 midwinter stratospheric warming, including a pre-warming pulse during the second half of November 1974, are indicated to affect the prevailing Wind in the meteor zone over Atlanta in a consistent manner, by making use of the latitudinal and vertical compensation of temperature and also the movement of pressure systems in the stratosphere and above.

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Murry L. Salby
and
R. G. Roper

Abstract

Meteor wind data taken over Atlanta (34°N, 84°W) during the three-year interval 1974–77 are analyzed for periodic fluctuations of a recurrent nature. Power spectra and cross spectra of the zonal and meridional velocities between 80 and 100 km are constructed for several samples.

Ensemble statistics indicate the regular appearance of periods near 17, 8, 5, 2, 1.6 and 1.2 days. Most of these display smaller spectral values near 90 km. The general seasonal behavior has maximum values in winter and minimum values in summer, paralleling the observed variation of traveling wave energy flux in the stratosphere.

The regularity with which these oscillations appear, tempts an association with the periods of atmospheric normal modes.

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C. G. Justus
,
R. G. Roper
,
Arthur Woodrum
, and
O. E. Smith

Abstract

An empirical atmospheric model has been developed which generates values for pressure, density, temperature and winds from surface levels to orbital altitudes. The output parameters consist of components for: 1) latitude, longitude, and altitude dependent monthly means; 2) quasibiennial oscillations; and 3) random perturbations to partially simulate the variability due to synoptic, diurnal, planetary wave and gravity wave variations. The monthly mean models consist of: (i) NASA's four dimensional worldwide model, developed by Environmental Research and Technology, for height, latitude, and longitude dependent monthly means from the surface to 25 km; and (ii) a newly developed latitude-longitude dependent model which is an extension of the Groves latitude dependent model for the region between 25 and 90 km. The Jacchia 1970 model is used above 90 km and is faired with the modified Groves values between 90 and 115 km. Quasibiennial and random variation perturbations are computed from parameters determined from various empirical studies, and are added to the monthly mean values. This model has been developed as a computer program which can be used to generate altitude profiles of atmospheric variables for any month at any desired location, or to evaluate atmospheric parameters along any simulated trajectory through the atmosphere. Various applications of the model are discussed, and results are presented which show that good simulation of the thermodynamic and circulation characteristics of the atmosphere can be achieved with the model.

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