Investigation of gravity wave momentum fluxes in the upper atmosphere derived from airlow / Investigação do fluxo de momento das ondas de gravidade na alta atmosfera através da aeroluminescência

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

In this study, momentum fluxes due to gravity wave propagation into the MLT region was calculated by using airglow image data and theoretical modeling. Airglow O(1S) 557,7, O2(0-1,b) and OH NIR images were obtained from Cachoeira Paulista (22,7°S; 45,0°W) and São João do Cariri (7,4°S; 36,6°W) and processed for estimation of gravity wave intrinsic parameters. One-dimensional linear model of gravity waves perturbing O(1S), O2(0-1,b) and OH emissions was carried out in order to derive amplitude and phase relations among multiple airglow layers in response to gravity waves with various intrinsic parameters and damping rates. Airglow weighted responses to waves are related through a cancellation factor (CF) for both intensity and temperature wave-induced amplitudes. The model showed that the layer centroid is lower in altitude and its full-width-half-maximum thickness is thinner than the unperturbed layers due to the wave perturbation. The vertical wavelength of the wave can be estimated from the relative phase information from different airglow layers, while damping of waves can be estimated from amplitude information. For an upward vertically propagating wave, the perturbation in upper layers leads perturbations in lower layers because the wave has downward phase propagation. Modeled parameters and airglow images were used for deducing momentum of high frequency, fast waves in multiple emissions. The results showed that dominant gravity waves disturb the intensity in 2,6-5% and carry momentum flux of 4,2-11,1 m2s-2. The momentum flux convergence between upper and lower airglow layers was also estimated. The strongest gravity wave forcing of 18 m/s/day was imposed to the meridional wind by gravity waves observed in Cachoeira Paulista during the winter time.

ASSUNTO(S)

gravity waves aeronomia geofÍsica espacial aeroluminescência sensoriamento remoto aeronomy image processing space geophysics alta atmosfera ondas de gravidade airglow ccd cameras processamento de imagens upper atmosphere remote sensing

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