Abstract
Abstract. We show in this report the momentum flux content input in the mesosphere due to relatively fast and small scale gravity waves (GWs) observed through OH airglow images. The acquisition of OH NIR images was carried out in Brazil at Brasilia (14.8° S, 47.6° W) and Cariri (7.4° S, 36.5° W) from September 2005 to November 2005 during the SpreadFEx Campaign. Horizontal wind information from meteor radar was available in Cariri only. Our findings showed strong wave activity in both sites, mainly in Cariri. High wave directionality was also observed in both sites during SpreadFEx, which have been observed by other investigators using different analysis' techniques and different types of data during the campaign. We discuss also the possibility of plasma bubble seeding by gravity waves presenting spatial and temporal scales estimated with our novel analysis technique during the SpreadFEx campaign.
Highlights
Atmospheric gravity waves have a great significance in the global circulation at mesosphere and lower thermosphere (MLT) region
We have focused on demonstrating spatial and temporal scales of gravity waves (GWs) detected in OH NIR images and their associated amplitudes and momentum fluxes during SpreadFEx campaign
GW penetration still depends on propitious atmospheric conditions, that is, the www.ann-geophys.net/27/2361/2009/
Summary
Atmospheric gravity waves have a great significance in the global circulation at mesosphere and lower thermosphere (MLT) region In this sense, there is considerable interest in measuring momentum fluxes carried by those waves (Holton, 1982; Gardner et al, 1999). Co-located optical imagers and radar wind instruments (mean horizontal wind information) at the same observation site are combined to provide intrinsic wave parameters (frequency, horizontal wavelength, direction of propagation), determined directly from the airglow. Swenson and Liu (1998) and Vargas et al (2007) have developed a method of representing analytically perturbations of the airglow emission radiance (ratio between the radiance I and temperature T variances) as a means of estimating wave momentum fluxes from all-sky airglow image data. A short discussion in terms of momentum fluxes is presented for two nights with evidence of strong correlation between wave motion followed by ionospheric plasma depletion, which are compared to the results obtained by Takahashi et al (2009)
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