A study of atmospheric oscillations in the meteor region above Grahamstown

Malinga, Sandile Bethuel (1995) A study of atmospheric oscillations in the meteor region above Grahamstown. Masters thesis, Rhodes University.

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Abstract

he dynamics of the atmospheric meteor region have been studied using the data obtained with - - the Grahamstown (33°16'S, 26<>:30'E) meteor radar between the years 1987 and 1993 inclusive. Harmonic analysis and the maximum entropy method (MEM) , were used for the spectral characterization ofthe wind above Grahamstown. The prevailing wind, tidal (periods 12- and 24- h) and other (periods 8- and 6-h) oscillations were extracted from the data using the guidelines agreed upon by the A TMAP community. Above Grahamstown the zonal and meridional prevailing winds were found to be predominantly eastward and equatorward respectively. Tidal amplitudes are comparable to the magnitude of the prevailing wind vector, with the diurnal tide being stronger than the semidiurnal tide. The phase differences between ,the zonal and meridional components of the semidiurnal and diurnal tides are - 2 hand - 5 h respectively, which is in reasonable agreement with the corresponding expected values of3 hand 6 h. The tidal wind vectors are on average elliptically polarized with anticlockwise rotation. Longitudinal and day-to-day tidal variations were studied. From the longitudinal study, the semidiurnal tide was found to be dominated by migrating modes, while the diurnal tidal behaviour suggests the presence of nonmigrating modes with zonal wavenumber s = 4. Tides were found to be variable from day to day with little apparent correlation between the zonal and meridional components of the respective tides.

Item Type:Thesis (Masters)
Uncontrolled Keywords:Mesosphere, Thermosphere, Atmosphere, Meteorology, Grahamstown, South Africa.
Subjects:Q Science > QC Physics
Divisions:Faculty > Faculty of Science > Physics & Electronics
Supervisors:Poole, L. M. G.
ID Code:3782
Deposited By: Mrs Carol Perold
Deposited On:23 Oct 2012 13:28
Last Modified:23 Oct 2012 13:28
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