%0 Journal Article
%4 sid.inpe.br/marciana/2004/01.12.10.20
%2 sid.inpe.br/marciana/2004/01.12.10.20.33
%@doi 10.1029/2002JD002593
%@issn 0148-0227
%@issn 2156-2202
%T An investigation of gravity wave activity in the low-latitude upper mesosphere: Propagation direction and wind filtering
%D 2003
%8 July
%9 journal article
%A Medeiros, Amauri Fragoso de,
%A Taylor, Michael J.,
%A Takahashi, Hisao,
%A Batista, Paulo Prado,
%A Gobbi, Delano,
%@affiliation Universidade Federal Campina Grande (UFCG)
%@affiliation Utah State University
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@electronicmailaddress afragoso@df.ufpb.br
%@electronicmailaddress michael.taylor@usu.edu
%@electronicmailaddress hisaotak@laser.inpe.br
%@electronicmailaddress ppbatista@laser.inpe.br
%@electronicmailaddress delanogobbi@laser.inpe.br
%B Journal of Geophysical Research
%V 108
%N D14
%P 4411 (8pp.)
%K airglow, winds, gravity waves, wind filtering, imager, nightglow emissions, critical level, shear flow, airglow, atmosphere, spectra, middle.
%X An all-sky charge-coupled device imager capable of measuring wave structure in the OH, O-2, and O I (557.7 nm) airglow emissions was operated at Cachoeira Paulista, Brazil (23degreesS, 45degreesW), for 2 years in collaboration with Utah State University, Logan. The dominant quasi-monochromatic gravity wave components investigated over a similar to1 year period (September 1998 to October 1999) have been extracted, and their seasonal variations have been measured. A total of 283 wave events were measured, exhibiting horizontal wavelengths from 5 to 60 km, observed periods from 5 to 35 min, and horizontal phase speeds of up to similar to80 m s(-1). The large-scale "band'' wave patterns (horizontal wavelength between 10 and 60 km) exhibited a clear seasonal dependence on the horizontal propagation direction, propagating toward the southeast during the summer months and toward the northwest during the winter. The direction of propagation was observed to change abruptly around the equinox period in mid March and at the end of September. Using a numerical simulation of gravity wave propagation in a seasonally variable climatological wind field, we have determined that the observed anisotropy in the wave propagation directions can be attributed to a strong filtering of the waves in the middle atmosphere by stratospheric winds.
%@language en
%3 jgrd9984.pdf