Observações de oscilações na aeroluminescência noturna na região equatorial.

Abstract

Mesospheric nightglow intensity measurements from São João do Cariri (7.40𝑆�,36.50𝑊�) in the equatorial region were studied to characterize gravity waves in at least, two different airglow emission layers. The data set starting from 2001 to 2007 was acquired using Multi-3 photometer and an all sky imager. The simultaneous observation of similar periodicities present in the airglow emission oscillations in two or more emission layers using the photometer permits the estimation of the period, vertical phase speed, vertical wavelength and vertical propagation direction. Using least square analysis, the phase and amplitude were determined for each observed wave. Using the dispersion relation for gravity waves, the horizontal wavelength were estimated as well and compared to the horizontal wavelength obtained by the all-sky imager. From the results of our estimation, the horizontal wavelength and vertical wavelength computed were 211.13 km and 27.88 km for the night of 14th October, 2006, and 216.03±9 km and 22.30km for 18th December respectively. Keogram analysis estimated 208.50 ± 24 km and 180.20 ± 25km for the 14th October and 18th December observation respectively. The observed wave of 14th October, 2006 was found to be propagating downward and the 18th December, 2006 was propagating upward.